Sunday, 29 August 2021

What’s wrong with Bluetooth Tracing?

We know that contact tracing is a critical part of our ability to contain any outbreak of an infectious disease. Bluetooth Tracing, offered through the NZ COVID Tracer app, is part of that process in New Zealand. Or at least, it should be. Technical folks over the last week have noticed that the most recent Bluetooth data made available to the NZ COVID Tracer app was on 17 August – the day we found out about Case A with the delta variant and the country went into lockdown. No Bluetooth keys have been uploaded to the central server since then, despite there being 512 positive cases at the time of writing. This therefore means that there have been very, very few Bluetooth-based exposure alerts sent to users. So why is there no Bluetooth Tracing data when there have been many Locations of Interest and related alerts sent out for QR code-based locations?

The Basics of Bluetooth Tracing
Before we go too far, let’s recap on what Bluetooth Tracing (BT) is supposed to do. NZ's Bluetooth system is built on the Apple/Google Exposure Notification Framework (often referred to as GAEN or ENF). Once it’s enabled on your phone, you go about your life as usual. As you wander around, your phone broadcasts an ID number (also known as a “key”). When your phone is physically close to another phone with BT enabled (within a couple of metres), the two phones exchange keys, and record them in a diary/log. If one of the two phone owners tests positive for COVID-19, they are then asked by public health officials to (voluntarily) upload the keys on their device to a central Ministry of Health (MOH) server. Phones with BT enabled are checking that server on a regular basis and, if there are new keys, will download them and check them against their log. If there is a match, then the user is notified about the match, and prompted to isolate and get a test. Importantly, MOH does not know the identity of people who have matched, so this system relies on people doing the right thing when notified. This is pretty similar to the QR code/venue-based system that runs in parallel, with the key difference that contact tracers can still send out an exposure notification if the case wasn’t using the app, by looking up the location in the system and finding the corresponding Global Location Number (GLN).

That’s it in a nutshell – there are other technical elements like rotating keys to help protect privacy and filtering to deal with noisy signals, but they are less relevant for the current problem. Prior to the current lockdown, there were approximately 1.5 million devices participating in BT each day, corresponding to about 35-40% of the adult population. But MOH told Newshub that “fewer than ten” Bluetooth-based alerts had been sent out. And a number of people have verified on their device that the last listed (GAEN-based) Exposure Notification check in the system settings was on the 17th or 18th of August. Given the rate of uptake across the population, it seems implausible that across 500+ cases there would have been no Bluetooth keys to upload to the MOH server, as that would imply that none of the 500+ individuals had BT turned on.

Close Contact Thresholds
One of the possible explanations that has been mooted is around the thresholds used for determining that one Bluetooth device has been close enough for long enough to another Bluetooth device to be considered a close contact with a reasonable risk of virus transmission. When the devices exchange keys, they also note how strong the signal is (as a proxy for distance) and the length of time they see the signal for. The GAEN protocol essentially multiplies these together to create a score, and there is a threshold that says if the score is above that value, then the two devices should be considered close contacts. While this is not an exact measure (especially due to the high variability of the signal strength), it can roughly translate to a close contact definition like “within 2m for 15 minutes”.

The thresholds can be inspected by checking the open-sourced code used in the NZ COVID Tracer app. The code probably doesn’t mean much to most people, but essentially the NZ thresholds are currently based on the Linux Foundation Public Health (LFPH) thresholds, mostly because Ireland uses the LFPH thresholds now, and our Bluetooth implementation is based on their code. However, a close contact definition of “2m for 15 minutes” seems incongruous with the data on how the delta variant of COVID-19 spreads. The increased transmissibility, and the documented cases of people getting infected simply by walking past an infectious person, indicate that the thresholds need to be much lower than they were in the past. This is the same reason why MOH has broadened its contact definitions to capture more people, basically treating anyone who was in a venue at the same time as an active case to be a close contact.

This has two implications on the current outbreak and the lack of Bluetooth keys being reported. Firstly, if the thresholds were too high, then the Bluetooth system could miss a lot of contacts that should be considered contacts. Secondly, if the public health officials know this, then they might have less confidence in the Bluetooth system.

However, the first justification does not actually explain what we are observing with the Bluetooth keys. This is because the central server should contain the keys of infected persons, which does not depend on any matching operation or any thresholds. The matching is done on the device once it has pulled the relevant keys from the server. So even if the thresholds are too high, we would still expect to see cases uploading their keys to the central server and to see devices performing the checks. To my understanding, MOH are investigating lowering the thresholds, but they need to do this carefully as lowering it too much could lead to many false positive matches (people being told they’re close contacts when they’re not). The second justification may have more merit, and we’ll come back to why it matters later.

Case Demographics and Digital Exclusion
Another possible explanation for the lack of BT notifications is based on the actual people involved in the current outbreak. At the time of writing, Ministry of Health statistics showed that 60% of the active cases were under the age of 30, and 70% of the active cases were Pacific Peoples. These two demographic groups are known to be less likely to be participating in BT. The reasons for this are less clear, and before I offer some of the justifications that have been discussed amongst experts, I’d note that the data to support these is incomplete at best.

The very young (11% of the cases are under 10) are not likely to have a smartphone. Young people generally appear to be more reluctant to participate in digital contact tracing, allegedly because they perceive the risk and consequence of getting COVID-19 to be low. Pacific Peoples are more likely to be digitally excluded so they may not have a smartphone. People in both groups may be more likely to have an older smartphone that is not compatible with BT, or they may have older batteries and are worried that BT may drain the battery life.

All of the above reasons come with strong caveats, because I don’t want readers to run off and say “aha, the lack of Bluetooth keys is easily explained by [insert unhelpful stereotype here]”. It’s just not that simple, and to make matters worse, I don’t think this is a good explanation because it doesn’t account for the rest of the active cases also not having their Bluetooth keys on the MOH server. There was a high enough proportion of people participating in BT for us to expect that at least one case (beyond Case A) would have had keys available to upload.

Household Transmission
Another mooted explanation is that after the initial rush of cases that were likely infected in the community, the majority of the cases have been within households. After all, if delta is infectious enough to be transmitted in open air after walking past an active case, then it’s pretty likely that living in the same house as an infectious person will lead to infection. Where a contact tracer is talking to a household contact, it seems plausible that they may not ask for the Bluetooth keys to be uploaded, because (a) the chain of transmission has already been established, and (b) if they know that the new case has been isolating at home for a couple of days, the risk of transmission outside of the home is relatively low. Again, this does not explain what’s happening for all 500+ cases, but it is logical that when the contact tracer is trying to move quickly and collect the most useful and relevant information, that they might focus on other information sources.

Capacity Constraints and Processes
This leads us to one of the more compelling explanations – that contact tracers are simply prioritising other tools ahead of BT. Digital contact tracing in New Zealand is not an automated process that runs by itself. It augments the human-led contact tracing process by providing information and processes that sit on top of the manual approach. So, for an active case’s Bluetooth keys to be uploaded to the MOH servers, a contact tracer has to (a) establish that the active case had BT on across the infectious period, (b) decide that sharing those keys would be useful to support contact tracing efforts, and (c) provide the active case with a code to type into their NZ COVID Tracer app to release the keys to the server. Then the active case has to (voluntarily) enter the code.

There are a couple of reasons that, when combined together, may explain why this process might not happen. With the location or venue-based approach (which is based on QR code data, manual entries, and interviews with the case), it is likely that most of the contacts will already be found. The venue-based approach casts a much wider net than the BT approach, because you can be in the same venue without necessarily being close enough to trigger the BT system. Imagine that an active case is wandering around a supermarket – there might be very few people who are within a few metres for more than a few minutes, but there would be a lot more people who were anywhere in the supermarket at the same time as the case.

This argument is further strengthened by the high BT thresholds currently in place, meaning that fleeting encounters outside of venues are unlikely to be captured by BT anyway. With the number of cases currently in the community, contact tracers are at full capacity (even using up all the extra surge capacity) just trying to call contacts and provide them with instructions. So, time-constrained contact tracers may decide that the extra time required to walk a case through the process of uploading BT keys is not worth it. After many discussions and thinking through all the possible explanations, it’s probably not a complicated technical reason that is leading to the absence of BT data being contributed to the contact tracing system. It’s probably a much simpler explanation: the contact tracers aren’t asking for the data.

Transparency and Clarity
Questions about the lack of Bluetooth keys have been put to MOH over the course of the last week, by myself and other members of the public, as well as by a number of journalists who have also asked me for comment. MOH has not provided a clear, defendable answer until the 1pm press conference on 29/08, when in response to a journalist question, Bloomfield pointed to the contact tracers not asking for Bluetooth information at the first case interview due to the number of cases, and also the demographic groups of the cases being less likely to use BT. He also claimed that “we have been using it where people have said they have Bluetooth turned on, and we’ve used that to send out messages,” but we know based on the MOH server that this has actually only happened for Case A. He added “we have given [the contact tracers] a nudge around that.”

I thought a lot about whether to write this article or not, because anything that might cause people to stop using NZ COVID Tracer is counterproductive in the age of delta. But MOH has had long enough to respond to queries and be upfront with the public about why Bluetooth isn’t being used. New Zealanders have been asked time and time again to “turn Bluetooth on”, and I have spent a lot of time trying to explain how it works, how to turn BT on, and why people should use it. It is frustrating to see the data potentially isn’t being used to support contact tracing. If, as I suspect, the explanation is that contact tracers simply aren’t asking for the information, then we need a policy decision as to whether this system is actually useful for contact tracing. If it is useful, then the contact tracing processes need to be amended to ensure that they are asking for BT information. If it is not useful, then we can have a different debate. Either way, this is about making sure we not only have the right tools to help us fight the virus, but that we are using them effectively.

To be clear, people should still use NZ COVID Tracer if they can, especially to scan QR codes and add manual entries. There is still a lot of potential for BT to be useful, but we need to know that it is actually being used.

PS: The BT data on the device deletes itself after 14 days (compared to 60 days for the QR code data), so MOH is limited in its ability to go back and start using it retrospectively. At this point, we've already lost the data related to cases during their infectious periods at the beginning of the outbreak (pre-lockdown).

Sunday, 22 August 2021

On Mandatory Recordkeeping for Contact Tracing

On 22 August 2021, Minister Chris Hipkins announced that recordkeeping for contact tracing purposes would become mandatory at "busy places and events" at all alert levels. Below are comments written for the Science Media Centre. I have also previous written about how businesses can support NZ COVID Tracer use.

The delta variant is much more transmissible than previous variants of COVID-19. We know that time-to-isolation is one of the key factors that determines how successful we are at containing any outbreak of the disease. Contact tracing is a key epidemiological tool that helps us identify the right people who need to isolate or get tested. Manual-only methods can be effective, but technology can significantly augment and speed up the process, giving ourselves the best chance of cutting off chains of transmission. Digital contact tracing supports this process by helping us keep track of our movements, and provide the information to contact tracers in a format that helps them act faster.

The government’s announcement today about mandatory recordkeeping for “busy places and events” (which translates roughly to the language of “higher-risk venues” that is used in overseas jurisdictions) at all alert levels is an important and significant step. The list given in the press conference includes “cafes, restaurants, bars, casinos and concerts, aged care, healthcare facilities (excluding patients), barbers, exercise facilities, nightclubs, libraries, courts, local and central government agencies, and social services providers with customer service counters.” The new rules will be introduced 7 days after we move down each alert level, applying to the set of venues that can open up at each level.

One of the big challenges with digital contact tracing in NZ has been the relatively low level of participation. Before the current outbreak of cases, only approximately 10% of New Zealand adults were scanning QR codes on a regular basis. The Bluetooth Tracing participation rate was more promising (around 35-40%), but this is still not high enough to give us confidence that the data will cover any outbreak anywhere in the country. Modelling from Te Pūnaha Matatini last year showed that we need at least 60%, and preferably 80%, of adults participating in digital contact tracing to have a meaningful impact on the reproducibility rate of COVID-19. With the delta variant, we need that participation rate to be higher than ever.

The international evidence suggests that making recordkeeping mandatory is the strongest driver for increasing the participation rate. Some form of mandated recordkeeping has been in place in Australia at a State level, in Singapore, Qatar, China, India, and previously in the United Kingdom. In New Zealand, we have seen evidence that even unenforced mandates (e.g. mask wearing on public transport) have a significant effect on behaviour, and that it sends a clear signal to the public on what the government expects is necessary for us to keep COVID-19 under control. The current penalties in the COVID-19 Response Act are not massive ($300-$1000), but they are under review and could increase.

It is important to note that this announcement relates to mandatory recordkeeping, not QR code scanning specifically. While people who cannot use NZ COVID Tracer are also welcome to try Rippl, venues will also be required to have pen and paper options available. It is important that businesses move away from using sheets of paper on clipboards, and use ballot boxes where available. With the sheets of paper, anyone can read the details of other people who have signed-in already, which can lead to some of the privacy breaches we saw last year with serious consequences. With the ballot box, individuals write their details on a small slip of paper, and then drop them into a box (like an election box) so that other members of the public cannot easily access them. Venues can then clear the box once a day, putting the slips of paper into a bag with the date on it in case they are needed by contact tracers later on, or otherwise discarding them after 60 days. The government has a ballot box template available online.

Business owners and those organising events will also be concerned about enforcement of recordkeeping. At this stage, the onus falls on them and their staff to enforce it – clearer guidance will need to be provided by the government on how those staff deal with people who insist on not providing their details. If it is too restrictive (e.g. people are turned away), there may be human rights implications if this means people cannot access services that provide basic needs. A common-sense balance needs to be struck between keeping the community safe, and not further antagonising those who choose not to comply.

This would also be a good opportunity for the government to invest into addressing the digital exclusion challenges that face many New Zealanders. By some estimates, as much as 20% of the adult population does not have access to a smartphone or the skills to use one effectively, and policies such as vouchers for smartphones or more funding for community skills training could help improve the proportion of NZers participating in digital contact tracing. That digital access and skills training will have long-term benefits beyond the pandemic as well.

It is also an opportunity for the government to introduce legislation that protects the data collected through digital contact tracing platforms to ensure that it can only ever be used for contact tracing purposes. In Singapore and in some Australian states, trust and confidence in digital contact tracing were significantly impacted when it was revealed that Police had accessed the data for law enforcement purposes. While New Zealand Police have stated that they “have not, and will not” use NZ COVID Tracer data for law enforcement purposes, legislation to create stronger penalties for misuse would further assure New Zealanders that participation is safe. Such legislation would also protect against employers or businesses misusing that data as well.

There are some risks that come with mandatory recordkeeping, but the government has the tools to mitigate many of them. For the rest of us, it serves as a reminder of the role that movement records play in the contact tracing process, and how critical it is for all of us to play our part. In the best-case scenario, we keep these records and then throw them away because we didn’t need them. But infected people and contacts having their records from before they get sick could make the difference between managing the outbreak successfully and the virus running out of control. We have all done a lot more, for a lot less.

Tuesday, 10 August 2021

Remarks at the Dialogue on Autonomous Weapons and Human Control

Mary Wareham of the Human Rights Watch and the Campaign to Stop Killer Robots organised an event with the Ministry for Foreign Affairs and Trade at Parliament to discuss New Zealand's role in disarmament of autonomous weapons. I was somewhat reassured by Minister Phil Twyford's ongoing calls for legally binding rules at an international level, but also agreed with Edwina Hughes' calls for domestic legislation as an easy first step before having to deal with the foibles of multilateralism. I gave a short speech with my Koi Tū hat on.

10 August 2021

Tēnā koutou katoa, ngā mihi nui mo te korero. I’d like to thank Mary Wareham for the invitation to speak to you all today on this important topic. Mary has been a global leader in this space for many years, and it’s great to have her home in NZ. I’ve been into technology since I was at primary school and entered a website design competition when I was nine. When I was finishing high school, I remember telling the school librarian that I was going to study engineering at university and build robots. The librarian said “That’s great! But please don’t end up building robots for the military.” 

I remember not really knowing what to say in response to that. At that point in my life, the notion of robots being used in armed warfare was largely limited to video games and science fiction movies. Killer robots were cool, because they were giant mechs with heavy armor plating and used big lasers and could fly and had dispassionate personalities that could drop pithy one liners. I had no idea that killer robots would in fact be quadcopter drones divebombing on retreating soldiers in Libya.

I didn’t end up building robots for the military in the end, I spent years training as a computer engineer developing AI systems, and now I’m just an academic that writes and talks about the societal impacts of digital technologies. There isn’t a lot of research about the ethics of killer robots being done in New Zealand. Discussions about autonomous weapons can feel distant from us at the bottom of the world. But we may be more involved than we think.

The nature of modern technology development means that no one develops a whole thing by themselves anyone. Everything that we do has been built upon the pieces made by developers and engineers before us. In an economics sense, Adam Smith called it the division of labour, but in engineering we call it abstraction and reuse and developing with off-the-shelf components. It means that we can save a lot of time and effort, avoiding mistakes by not reinventing the wheel. But it also means that if we make something, it can be very difficult to control where that might end up. We just don’t know how someone might use something that we built. Which means that we don’t know if a piece of software written to control drones in New Zealand might end up in a device used to kill a person halfway around the world. Even if we pledge not to participate in or support the development of lethal autonomous weapons, we cannot guarantee that our code or our electronics or our hardware won’t have a hand in ending a life.

I can’t speak on behalf of the entire tech community, but I know that many of my colleagues are increasingly worried about the social and ethical implications of the tools and systems that we develop. In a technology space where the ethics are often murky, where we often have debates about free speech and safe harbour for platforms and discriminatory impacts of automation and so on, there really should be no question about autonomous weapons. When it comes to the decision to end a person's life, we cannot allow some lines of code take that humanity away from us.

I note that the Minister has spoken about the future impact of autonomous weapons, but autonomous weapons have been technically feasible for a long time. Weapon systems can be programmed to select targets and apply force without human intervention, and have existed for years even if they haven’t necessarily been operationalised. It is only our ethics thus far that have stopped the broader deployment of these weapons, and that is not a sufficient barrier to make us feel comfortable that these weapons won’t be used. We are already playing catch-up.

A legally binding instrument would go a long way. We’ve already collectively decided as a species that there are some weapons that are just too horrible to use. I think we all know what the problems are with killer robots, we can move on from showing concern and relitigating definitions and get onto debating the solutions. It boggles my mind that we spent so long debating the definition of killer robots, with one of the commonly used examples being that land mines could also be considered autonomous weapons because there is no human decision to detonate, to which I’d say, we should ban land mines too!

And New Zealand has a role to play as a leader on this issue. We have an impact on the global digital technology space, whether that’s through the Christchurch Call or through advancing indigenous data sovereignty. We are in a position to have a strong stance on autonomous weapons, to draw the support of those sitting on the fence, to help protect all humans everywhere in the world from this impassive evil. A national strategy that leads to international engagement on autonomous weapons is critical, because we have both an opportunity and an imperative to ensure that killer robots stay in the fiction part of science fiction. I’m sure that would make my school librarian feel more comfortable at least. Ngā mihi nui mo te whakarongo pīkari, thank you. 

Saturday, 7 August 2021

A collection of NZ COVID Tracer Tweet Threads

A lot of my work on monitoring the deployment of NZ COVID Tracer has been disseminated through Twitter. While I keep track of media appearances, what I say has often been "interpreted" by journalists (which is not inherently a bad thing), whereas I have control over what is said from my account on Twitter. But Twitter threads are more ephemeral, so it's useful to collate them here so I can refer back to them later. Media appearances are tracked at https://www.andrewchen.nz/ (see Blogs and Writing and Politics and Talks).

2-4 April 2020, Discussions and media appearances on digital contact tracing: https://twitter.com/andrewtychen/status/1245422705442058240?s=20 and  https://twitter.com/andrewtychen/status/1244843687005130752?s=20 and https://twitter.com/andrewtychen/status/1246193656337330176?s=20 and https://twitter.com/andrewtychen/status/1245814752963522561?s=20 and https://twitter.com/andrewtychen/status/1245476885514964999?s=20

6 April 2020, Hard decisions in digital contact tracing: https://twitter.com/andrewtychen/status/1246987251021574144?s=20

7-11 April 2020, Various discussions on Bluetooth digital contact tracing: https://twitter.com/andrewtychen/status/1247306049872257025?s=20 and https://twitter.com/andrewtychen/status/1248058174801760256?s=20 and https://twitter.com/andrewtychen/status/1248795601061330944?s=20 and https://twitter.com/andrewtychen/status/1248776265869352960?s=20

20 April 2020, Verrall report: https://twitter.com/andrewtychen/status/1252104637236183040?s=20

27 April 2020, TraceTogether vs Apple/Google ENF: https://twitter.com/andrewtychen/status/1254581777315753985?s=20

6 May 2020, Govt statements on digital contact tracing: https://twitter.com/andrewtychen/status/1257853008127201280?s=20 and https://twitter.com/andrewtychen/status/1257846308242550784?s=20

8 May 2020, On evaluating digital contact tracing options: https://twitter.com/andrewtychen/status/1258558311638552583?s=20

11 May 2020, Misuse of contact tracing data and govt app alluded to: https://twitter.com/andrewtychen/status/1259788892061876224?s=20 and https://twitter.com/andrewtychen/status/1259738058234060800?s=20

15 May 2020, Apple/Google ENF announced and OPC conducts international literature review: https://twitter.com/andrewtychen/status/1261242541728395269?s=20 and https://twitter.com/andrewtychen/status/1261074033073741825?s=20

18 May 2020, Digital diary app announced: https://twitter.com/andrewtychen/status/1262115935415984128?s=20 and https://twitter.com/andrewtychen/status/1262218807596072961?s=20

19-20 May 2020, NZ COVID Tracer app released: https://twitter.com/andrewtychen/status/1262639539962576896?s=20 and https://twitter.com/andrewtychen/status/1262657557522296833?s=20 and https://twitter.com/andrewtychen/status/1262681583602941952?s=20 and https://twitter.com/andrewtychen/status/1262687219036205056?s=20 and https://twitter.com/andrewtychen/status/1262699505620643840?s=20 and https://twitter.com/andrewtychen/status/1262920262888108035?s=20

20 May 2020, On QR code compatibility: https://twitter.com/andrewtychen/status/1262965446497746946?s=20

21 May 2020, App update and QR code standard released: https://twitter.com/andrewtychen/status/1263293181266767872?s=20 and https://twitter.com/andrewtychen/status/1263275020328955907?s=20 and https://twitter.com/andrewtychen/status/1263255922001891328?s=20

22-28 May 2020, NZ COVID Tracer usage: https://twitter.com/andrewtychen/status/1263637276212334593?s=20 and https://twitter.com/andrewtychen/status/1264359904858402817?s=20 and https://twitter.com/andrewtychen/status/1264774348784627712?s=20 and https://twitter.com/andrewtychen/status/1265145628113252354?s=20 and https://twitter.com/andrewtychen/status/1265811730761834496?s=20

27 May 2020, Collecting QR code placement: https://twitter.com/andrewtychen/status/1265362761229320192?s=20 and https://twitter.com/andrewtychen/status/1269724798432579584?s=20

27 May 2020, Ballot boxes for paper sign-in: https://twitter.com/andrewtychen/status/1265471492650754048?s=20

27 May 2020, Office of the Privacy Commissioner audits contact tracing apps: https://twitter.com/andrewtychen/status/1265411186884898816?s=20

29 May 2020, Public Health Response Order amended: https://twitter.com/andrewtychen/status/1266224917562798082?s=20

30 May 2020, Digital contact tracing also being used for marketing purposes: https://twitter.com/andrewtychen/status/1266524672499150848?s=20

30-31 May 2020, NZ COVID Tracer usage: https://twitter.com/andrewtychen/status/1266542569770512384?s=20 and https://twitter.com/andrewtychen/status/1266898399409799168?s=20

1-8 June 2020, Updates on NZ COVID Tracer usage: https://twitter.com/andrewtychen/status/1267266106525286400?s=20 and https://twitter.com/andrewtychen/status/1267986164297785345?s=20 and https://twitter.com/andrewtychen/status/1268348162185375746?s=20 and https://twitter.com/andrewtychen/status/1268727452529946624?s=20 and https://twitter.com/andrewtychen/status/1269812242171584512?s=20

10 June 2020, NZ COVID Tracer app update with corresponding PIA: https://twitter.com/andrewtychen/status/1270533004490760192?s=20 and https://twitter.com/andrewtychen/status/1270572400287952896?s=20

13 June 2020, NZ COVID Tracer QR code generation: https://twitter.com/andrewtychen/status/1271595654452670465?s=20

16 June 2020, Norway suspends use of their digital contact tracing app: https://twitter.com/andrewtychen/status/1272626615256641537?s=20

16 June 2020, A reminder to keep track of where you've been: https://twitter.com/andrewtychen/status/1272727624716967936?s=20

19 June 2020, Diagnosing NZ COVID Tracer app failure (token expiring one month after release): https://twitter.com/andrewtychen/status/1273795572336439297?s=20

26 June 2020, QR code fragmentation: https://twitter.com/andrewtychen/status/1276248099405492224?s=20

26 June 2020, Contact tracing proactive release docs: https://twitter.com/andrewtychen/status/1276290439151153153?s=20

29 June 2020, MOH works with third-party vendors to develop APIs: https://twitter.com/andrewtychen/status/1277455138525810688?s=20

4 July 2020, Singapore does open design of TraceTogether tokens: https://twitter.com/andrewtychen/status/1279226167178887171?s=20

7 July 2020, NZ COVID Tracer usage stats: https://twitter.com/andrewtychen/status/1280288120080982016?s=20

9 July 2020, On effectiveness of digital contact tracing: https://twitter.com/andrewtychen/status/1281181379972096001?s=20

15 July 2020, Reacting to Minister Chris Hipkins on digital contact tracing: https://twitter.com/andrewtychen/status/1283341335647281152?s=20

18 July 2020, On mandatory digital contact tracing participation: https://twitter.com/andrewtychen/status/1284260907292307456?s=20

21 July 2020, Would you voluntarily use Bluetooth-based digital contact tracing? https://twitter.com/andrewtychen/status/1285335307101933568?s=20 and https://twitter.com/andrewtychen/status/1285310546057637888?s=20

24 July 2020, Airport security tells me off for scanning a QR code: https://twitter.com/andrewtychen/status/1286553818914672641?s=20

26 July 2020, CovidCard politics: https://twitter.com/andrewtychen/status/1287139015360040960?s=20 and https://twitter.com/andrewtychen/status/1287278228231450624?s=20

30 July 2020, NZ COVID Tracer app update to introduce manual entries: https://twitter.com/andrewtychen/status/1288636909632151552?s=20

31 July 2020, Proactive release of digital contact tracing documents: https://twitter.com/andrewtychen/status/1289000328491200512?s=20

31 July 2020, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1289018177964216320?s=20

5 August 2020, Mandatory QR code poster display: https://twitter.com/andrewtychen/status/1290756441096118272?s=20

6 August 2020, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1291105726383849472?s=20

6 and 7 August 2020, CovidCard: https://twitter.com/andrewtychen/status/1291178655356538881?s=20 and https://twitter.com/andrewtychen/status/1291549026186223616?s=20

11-15 August 2020, NZ COVID Tracer usage and contact tracing during beginning of second wave: https://twitter.com/andrewtychen/status/1294405444845199361?s=20 and https://twitter.com/andrewtychen/status/1294442980900655105?s=20 and https://twitter.com/andrewtychen/status/1294124899993128960?s=20 and https://twitter.com/andrewtychen/status/1294078405546139648?s=20 and https://twitter.com/andrewtychen/status/1293717699088924672?s=20 and https://twitter.com/andrewtychen/status/1293400650861015041?s=20 and https://twitter.com/andrewtychen/status/1293145349582807040?s=20 and https://twitter.com/andrewtychen/status/1293117587031642112?s=20

16 August 2020, On consolidating QR code posters to the NZ COVID Tracer app: https://twitter.com/andrewtychen/status/1294809501661446145?s=20 and https://twitter.com/andrewtychen/status/1294809157325922304?s=20

16 August 2020, How many QR code scannable places does the average person visit in a day? https://twitter.com/andrewtychen/status/1294754821430337541?s=20 and  https://twitter.com/andrewtychen/status/1294814699200999426?s=20

17-18 August 2020, NZ COVID Tracer usage and other contact tracing stats: https://twitter.com/andrewtychen/status/1295174058800107521?s=20 and https://twitter.com/andrewtychen/status/1295529716267364352?s=20 and https://twitter.com/andrewtychen/status/1295537467660017664?s=20 and https://twitter.com/andrewtychen/status/1295537467660017664?s=20 and https://twitter.com/andrewtychen/status/1295593335701217280?s=20 and https://twitter.com/andrewtychen/status/1295594257852461057?s=20

22 and 24 August 2020, NZ COVID Tracer usage stats: https://twitter.com/andrewtychen/status/1296927235853529094?s=20 and https://twitter.com/andrewtychen/status/1297703985520840704?s=20

25 August 2020, Politicians debate NZ COVID Tracer in Parliament: https://twitter.com/andrewtychen/status/1298083424452763649?s=20

25 August 2020, Technology in MIQ facilities: https://twitter.com/andrewtychen/status/1298086363951063040?s=20

26 August 2020, International drivers and barriers to using digital contact tracing: https://twitter.com/andrewtychen/status/1298462726633615360?s=20

27 August 2020, CTAC report released: https://twitter.com/andrewtychen/status/1298788370265468928?s=20

28 August 2020, TPM modelling on digital contact tracing: https://twitter.com/andrewtychen/status/1299122399359639553?s=20

1 and 2 September 2020, CovidCard team stands down and op-eds breathlessly claiming we needed CovidCard: https://twitter.com/andrewtychen/status/1300567595511234560?s=20 and https://twitter.com/andrewtychen/status/1300986907946491905?s=20

2 September 2020, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1301074325097779200?s=20

9 September 2020, On media announcements of exposures: https://twitter.com/andrewtychen/status/1303582491324809218?s=20

11 September 2020, NZ COVID Tracer usage stats: https://twitter.com/andrewtychen/status/1304296338356461570?s=20

12 September 2020, On "track and trace": https://twitter.com/andrewtychen/status/1304588020742410241?s=20

14 September 2020, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1305419256583004161?s=20

16 September 2020, On people saying that Singapore has released CovidCard and that NZ should follow suit: https://twitter.com/andrewtychen/status/1306048769167777792?s=20

18 September 2020, UK NHSX app: https://twitter.com/andrewtychen/status/1306702223942934528?s=20

22 September 2020, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1308275491996983297?s=20

24 September 2020, Level 1 QR code display reminder and delayed OIA release: https://twitter.com/andrewtychen/status/1308850727473811456?s=20 and https://twitter.com/andrewtychen/status/1308917248355176448?s=20

2 October 2020, Proactive release docs on CovidCard: https://twitter.com/andrewtychen/status/1311843749916340224?s=20

8 October 2020, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1314020915844317186?s=20

9 October 2020, Proactive releases from MOH on contact tracing: https://twitter.com/andrewtychen/status/1314288142271176704?s=20 and https://twitter.com/andrewtychen/status/1314308394266759169?s=20

13 October 2020, Tracking the CovidCard story: https://twitter.com/andrewtychen/status/1315882969534361600?s=20

18 October 2020, Importance of contact tracing records: https://twitter.com/andrewtychen/status/1317653089277546497?s=20

19 October 2020, Public transport QR codes: https://twitter.com/andrewtychen/status/1317939354375917568?s=20

20 and 21 October 2020, NZ COVID Tracer usage graph and how to be more interesting: https://twitter.com/andrewtychen/status/1318328262154543104?s=20 and https://twitter.com/andrewtychen/status/1318646229836836864?s=20

23 October 2020, NZ COVID Tracer memes: https://twitter.com/andrewtychen/status/1319363647781490688?s=20

23 and 24 October 2020, App reminder notification for long weekend and Chinese phone issues: https://twitter.com/andrewtychen/status/1319366906638299136?s=20 https://twitter.com/andrewtychen/status/1319431384885161984?s=20 and https://twitter.com/andrewtychen/status/1319737242257031168?s=20

25 October 2020, International interoperability of ENF in Europe: https://twitter.com/andrewtychen/status/1320103392660705280?s=20

27 October 2020, Marine worker scare and NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1320156147068719104?s=20 and https://twitter.com/andrewtychen/status/1320897568058949632?s=20

29 October 2020, CovidCard OIA refusal: https://twitter.com/andrewtychen/status/1321620038072193027?s=20

31 October 2020, Periodicity of NZ COVID Tracer usage: https://twitter.com/andrewtychen/status/1322297321544019969?s=20

3 and 9 and 12 November 2020, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1323438784743010305?s=20 and https://twitter.com/andrewtychen/status/1325651745477812224?s=20 and https://twitter.com/andrewtychen/status/1326685304804110336?s=20

13 November 2020, NZ COVID Tracer and Google Mobility Statistics: https://twitter.com/andrewtychen/status/1327143505270108160?s=20

15 and 19 November 2020, NZ COVID Tracer usage post-Auckland CBD case: https://twitter.com/andrewtychen/status/1327788678547087360?s=20 and https://twitter.com/andrewtychen/status/1329290488298446848?s=20

23 November 2020, NZ COVID Tracer update to no longer require registration: https://twitter.com/andrewtychen/status/1330713066846097408?s=20

24 November 2020, CovidCard doc release on FYI: https://twitter.com/andrewtychen/status/1330978619590467584?s=20

27 November 2020, NZ COVID Tracer usage graphs: https://twitter.com/andrewtychen/status/1332113610252795904?s=20

9 and 10 December 2020, Bluetooth Tracing released: https://twitter.com/andrewtychen/status/1336371429697146880?s=20 and https://twitter.com/andrewtychen/status/1336752222755987456?s=20

11 December 2020, Data stays on the device (via PIA): https://twitter.com/andrewtychen/status/1337190987651641344?s=20

12 December 2020, Checking Exposure Keys: https://twitter.com/andrewtychen/status/1337484983305322496?s=20

13 December 2020, On Bluetooth Tracing launch: https://twitter.com/andrewtychen/status/1337921196977897472?s=20

21 December 2020, NZ COVID Tracer usage stats: https://twitter.com/andrewtychen/status/1340866546520846339?s=20

3 January 2021, Bluetooth Tracing reminder: https://twitter.com/andrewtychen/status/1345591885973241859?s=20

5 January 2021, Singapore Police uses digital contact tracing data: https://twitter.com/andrewtychen/status/1346167613454389248?s=20

11 January 2021, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1348432804191760385?s=20

12 January 2021, Good QR code placement thread: https://twitter.com/andrewtychen/status/1348830608399626240?s=20

13 January 2021, On making NZ COVID Tracer mandatory: https://twitter.com/andrewtychen/status/1349061262181691392?s=20

14 January 2021, NZ COVID Tracer app permissions vs social media apps: https://twitter.com/andrewtychen/status/1349573048341389319?s=20

17 January 2021, Bluetooth Tracing on: https://twitter.com/andrewtychen/status/1350599246513283074?s=20

20 January 2021, Pokemon Go and gamification: https://twitter.com/andrewtychen/status/1351654935624994817?s=20

24 and 25 January 2021, Reacting to the Northland case: https://twitter.com/andrewtychen/status/1353189712115113984?s=20 and https://twitter.com/andrewtychen/status/1353436421277671424?s=20 and https://twitter.com/andrewtychen/status/1353258689050734592?s=20 and https://twitter.com/andrewtychen/status/1353497399847579649?s=20 and https://twitter.com/andrewtychen/status/1353183170712137730?s=20

27 January 2021, NZ COVID Tracer usage stats: https://twitter.com/andrewtychen/status/1354207488816553986?s=20

27 January 2021, Tips for scanning QR codes: https://twitter.com/andrewtychen/status/1354238483175329794?s=20

27 January 2021, Boycotting Magic Talk Radio: https://twitter.com/andrewtychen/status/1354333799501295616?s=20

29 and 31 January 2021, NZ COVID Tracer usage: https://twitter.com/andrewtychen/status/1354906560707710978?s=20 and https://twitter.com/andrewtychen/status/1355714277944909827?s=20

5 February 2021, NZ COVID Tracer usage graph: https://twitter.com/andrewtychen/status/1357470356991143938?s=20

5 February 2021, Minister response to letter asking for legislative protections: https://twitter.com/andrewtychen/status/1357513598734532609?s=20

11 February 2021, OIA on the costs of the NZ COVID Tracer app: https://twitter.com/andrewtychen/status/1359704072215879680?s=20

14 February 2021, Reacting to Valentine's Day Cluster: https://twitter.com/andrewtychen/status/1360778219129954307?s=20

15 February 2021, Bluetooth Tracing crosses 1 million mark: https://twitter.com/andrewtychen/status/1361123396218617857?s=20

16 February 2021, NZ COVID Tracer usage stats through the Valentine's Day Cluster: https://twitter.com/andrewtychen/status/1361434163237117955?s=20 and https://twitter.com/andrewtychen/status/1362524774568583168?s=20

17 February 2021, Auckland cases didn't use NZ COVID Tracer: https://twitter.com/andrewtychen/status/1361893987859144707?s=20

17 February 2021, Seven Sharp accidentally tells people they need to scan out: https://twitter.com/andrewtychen/status/1361936209195401219?s=20 and https://twitter.com/andrewtychen/status/1362284032046755842?s=20

18 February 2021, How businesses can encourage use of NZ COVID Tracer:
https://twitter.com/andrewtychen/status/1362153227383267330?s=20

25 February 2021, NZ COVID Tracer usage in graphs: https://twitter.com/andrewtychen/status/1364699540310224897?s=20

27 February 2021, Digital contact tracing and isolation: https://twitter.com/andrewtychen/status/1365577364911001600?s=20

28 February 2021, NZ COVID Tracer button change from "Finish" to "Okay": https://twitter.com/andrewtychen/status/1365761281639084032?s=20

1 March 2021, Bluetooth and the Auckland cases: https://twitter.com/andrewtychen/status/1366150729358958592?s=20 and https://twitter.com/andrewtychen/status/1366167569376309250?s=20

3 March 2021, Hipkins says CovidCard trials not hugely successful: https://twitter.com/andrewtychen/status/1366829278977908741?s=20

7 and 16 March 2021, NZ COVID Tracer usage statistics: https://twitter.com/andrewtychen/status/1368325665590677509?s=20 and https://twitter.com/andrewtychen/status/1371577789669777410?s=20

25 March 2021, NZ COVID Tracer update with v2 of ENF: https://twitter.com/andrewtychen/status/1374888783850528770?s=20

01 April 2021, Easter weekend reminder: https://twitter.com/andrewtychen/status/1377419243503804422?s=20

08 April 2021, New "gamification" update and the push for users to enter a manual entry when they stay at home: https://twitter.com/andrewtychen/status/1379887281545256964?s=20 and https://twitter.com/andrewtychen/status/1382780397839273991?s=20

12 April 2021, A reminder that the NZ COVID Tracer app is decentralised and not effective state surveillance: https://twitter.com/andrewtychen/status/1381349468839153665?s=20

12 April 2021, UK NHS COVID-19 app has update blocked by Apple/Google: https://twitter.com/andrewtychen/status/1381549786986246145?s=20

18 April 2021, A look at perception of risk and public holidays: https://twitter.com/andrewtychen/status/1383656698150219779?s=20

13 May 2021, NZ COVID Tracer usage data after opening of Australian travel bubble: https://twitter.com/andrewtychen/status/1392796308365201414?s=20

20 May 2021, One year reflection on launch of NZ COVID Tracer: https://twitter.com/andrewtychen/status/1395249081375543296?s=20 (and an article on Newsroom: https://twitter.com/andrewtychen/status/1394757661527220225?s=20)

28 May 2021, V5.0 of NZ COVID Tracer: https://twitter.com/andrewtychen/status/1397287241605468164?s=20

04 June 2021, Queen's Birthday weekend reminder: https://twitter.com/andrewtychen/status/1400645017081769989?s=20

15 June 2021, Responding to news that Western Australia Police access digital contact tracing data to support investigations: https://twitter.com/andrewtychen/status/1404727616628690944?s=20 and https://twitter.com/andrewtychen/status/1405255177599209474?s=20

23 June 2021, Responding to the Wellington scare/case and Alert Level 2: https://twitter.com/andrewtychen/status/1407431447976103940?s=20

28 June 2021, Responding to government noting that it is considering making checking-in (with pen and paper or NZ COVID Tracer) mandatory in high-risk venues: https://twitter.com/andrewtychen/status/1409379769368465408?s=20

02 July 2021, Telling Neon not to co-opt government COVID advertising motifs in their Love Island ads: https://twitter.com/andrewtychen/status/1410786561688408065?s=20

02 July 2021, Further plea for legislative protections for digital contact tracing data after more reports of Australian police forces using that data in each State: https://twitter.com/andrewtychen/status/1410787358895714305?s=20

06 July 2021, NZ COVID Tracer usage data around the Australian scare in Wellington: https://twitter.com/andrewtychen/status/1412230602871369730?s=20

23 July 2021, A Twitter poll on NZ COVID Tracer use and the disconnect with actual usage statistics: https://twitter.com/andrewtychen/status/1418317249790627842?s=20

29 July 2021, V6.0.0 or Release 8 of NZ COVID Tracer released: https://twitter.com/andrewtychen/status/1420590258312212486?s=20

01 August 2021, Media chooses not to cover latest NZ COVID Tracer update: https://twitter.com/andrewtychen/status/1421588947877072897?s=20

07 August 2021, MOH/DIA joint briefing paper on CovidCard to Minister Chris Hipkins finally concluding that CovidCard is not to be deployed nationally: https://twitter.com/andrewtychen/status/1423819815601381378

12 August 2021, Response to government announcement of re-opening plans: https://twitter.com/andrewtychen/status/1425681856502976519?s=20 and https://twitter.com/andrewtychen/status/1425718633917927431?s=20

14 August 2021, On differences in estimates of how much QR code scanning there should be: https://twitter.com/andrewtychen/status/1426326931218132994?s=20