#### Safe Blues at The University of Auckland Update: Aug 23, 2021. See more updates [here](https://ai4pandemics.org/auckland-safeblues/)

# NZ COVID counts increase: a digital experiment at Auckland Uni demonstrates lockdown works

**By the [Safe Blues](https://safeblues.org/) team**

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An experiment running at the University of Auckland could provide near-real-time information on the likely spread of Covid. In the experiment, virtual (not real!) viruses are spread within an Android app that members of the experiment run on their phone. When two members of the experiment get close to one another, their phones communicate by Bluetooth, mimicking the spread of real epidemics. Information on virtual virus counts is available almost in real time, as opposed to real infections from Covid, which may only be detected several days after exposure.

The researchers running the experiment use statistics and machine-learning techniques to predict what is happening with the real virus based on the information from the virtual viruses, which they call Safe Blues strands, since the virtual viruses are spread using Bluetooth. Each phone running the Safe Blues app carries many different strands. It is the combination of the strands that gives the experiment the ability to predict how the real virus is spreading.


>**In the figure: The evolution of several Safe Blues strands (virtual epidemics). The green curves are counts of exposed participants (infected but still not infectious). The initial weekly cycle can be clearly seen, with fewer numbers at the weekends. The blue curves are infected participants. The vertical red line is the date of the lockdown. Now, after 5 days of lockdown, the system’s live measurements are already showing that the number of exposed participants is decreasing, as reflected in the number of incubating participants. This indicates that the lockdown is working, but this information is not available to decision makers except through Safe Blues. Meanwhile, the number of infected participants is holding approximately constant.**

Delta cases were discovered in Auckland, New Zealand early last week and the country quickly entered lockdown. The first case was discovered on Tuesday Aug 17, and now on Monday Aug 23 there are 107 confirmed community cases.

Since the start of the COVID-19 outbreak, New Zealand has been considered a COVID safe haven. Rapid initial responses crushed the pandemic to date leading to around 3,000 cases in total since the start of the pandemic. For a population of around 5 million people, this is one the lowest infection rates in the world.

However the recent delta outbreak is very concerning. This is especially the case given the rising numbers in parts of nearby Australia.

Meanwhile, there is an ongoing [experiment](https://safeblues.org/experiment) at the University of Auckland. The experiment uses a framework called Safe Blues, where virtual tokens are spread via Bluetooth between the phones of participants, mimicking the spread of a real-world virus. In this ethics approved experiment, students and staff run the Safe Blues app in the background on their Android device. When students are physically close to each other, their phones exchange tokens which then spread, mimicking the dynamics of the real epidemic. This allows researchers to estimate the spread rate of a real virus.

The goal of Safe Blues is to gain better information about human contact trends while preserving privacy. This is not for tracking individuals but rather for learning about the overall rate of virus spread and the effect of social distancing measures such as lockdown in controlling this spread. Ultimately statistical techniques and AI can use real-time Safe Blues measurements to predict the current state of the epidemic.

In the short term following the flash Auckland lockdown, the Safe Blues experiment is already giving signals showing that the lockdown works to inhibit the spread of both COVID-19 as well as Safe Blues strands.

The experiment involves hundreds of digital token variants with varying (simulated) disease attributes. For example, one set of variants has a random incubation period with a mean of 3 days, and a random disease duration (during which a phone can infect other phones) with a mean of 10 days. This is somewhat similar to COVID-19. The above figure illustrates the trajectories of twelve repetitions of such a virus.

To be clear, this is not a simulation run on a computer, it is the spread of virtual tokens between participants on the University of Auckland campus, based on the real-world interaction of participants in the experiment. If participants are socially distant and do not interact; then neither the COVID-19 virus nor the Safe Blues tokens can propagate.

A random subset of the phones belonging to participants in the experiment was infected with this virtual virus three weeks ago, and on the day of the New Zealand lockdown an average of about 25 participant phones were infected with each such repetition. Due to chance, this number is of the same order as the estimated state of the delta strain on that day.

Now, after 5 full days of lockdown, the system’s live measurements are already showing that the number of exposed participants is decreasing, as reflected in the number of incubating participants. However, the number of infected participants remains constant.

With real COVID cases, one cannot measure exposed cases, and hence the effect of the lockdown is not yet visible on the actual case numbers in New Zealand. Safe Blues however, allows us to immediately see the actual effect of lockdown measures, at least in the subset of the population that has the app on their devices. In the coming days we’ll continue to track the state of the Safe Blues virtual safe epidemics in parallel to actual case numbers reported from New Zealand.

Do you typically spend time on the University of Auckland campus? You are invited to [join](https://participant.safeblues.org/join) the experiment.