Researchers' virtual experiment mimics our Delta outbreak

A virus transmission experiment run by the University of Auckland is using virtual tokens to mimic the potential spread of COVID-19’s Delta variant.

The experiment uses a framework called Safe Blue, where tokens are spread via Bluetooth between the phones of participants.

On July 29, 600 virtual virus tokens were released to 192 participants' phones.

When physically close to each other, the participants exchange tokens which then spread, imitating the dynamics of the real virus.

Providing near-real-time information, the experiment allows researchers to estimate the current spread rate of Covid-19.

The digital tokens carry varying strands of the virus. For example, one set of virtual variants has a random incubation period with an average of three days, and a random infectious period of 10 days.

It is the combination of the strands that gives the experiment the ability to predict how the virus is spreading in real life, says researcher Dr Azam Asanjarani, from the university’s Department of Statistics.

“Safe Blues can tell us about contact trends to help learn about the overall rate of virus spread and the effect of social distancing in controlling it.

“If participants are socially distant and do not interact, then neither the COVID-19 virus nor the Safe Blues tokens can propagate,” says Dr Asanjarani.

The Safe Blues experiment is revealing the contract trends of the current Delta outbreak in Auckland.

“The main point after seven days of running the experiment is that our results show the effectiveness of lockdown in controlling the virus spread,” says Dr Asanjarani.

This graph shows the evolution of several Safe Blues strands (virtual viruses) after six days of lockdown. Image: supplied

The green curves in the above figure are counts of exposed participants. The blue curves are infected participants.

The system’s live measurements show the number of exposed and incubating participants is decreasing after the implementation of lockdown, while 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 allows us to immediately see the actual effect of lockdown measures - in the subset of the population that has the app on their devices.”

Track live updates of the experiment  and find out more about Safe Blue.