China have enforced a variety of measures aimed at social distancing including lockdowns, restrictions on movement and cordon-sanitaires, as well as the Alipay Health Code smartphone application (an add on to the WeChat app system) now adopted in over 200 cities and by 90% of individuals in one Chinese province. A separate system has been implemented in South Korea, and both have come under public scrutiny over issues of data protection and privacy. We sought to design a broadly acceptable version of this platform, leveraging commonly used smartphone functionality. This system is currently in development, and based on a very simple algorithm, that we show through mathematical modelling will enable public health agencies to prevent a COVID-19 epidemic while minimizing social and economic disruption.This also introduced me to a new concept, “herd protection”, which is described as “Ronald Ross’s great discovery: you don’t need to stop all infections to stop an epidemic, you need to get and keep R<1."
COVID-19 has a relatively long infectious incubation period, averaging five days but potentially up to two weeks, during which there may be asymptomatic transmission. In other words, there may be a period of time in which people who carry COVID-19 don’t necessarily show symptoms and may not even realise they are infected, but are still capable of infecting others. This makes it harder for health professionals and epidemiologists to trace who has come into contact with infected persons (‘contact tracing’), which in turn makes the virus more difficult to effectively contain. Many people, however, now carry GPS-enabled smartphones which already track their location over time – most mapping apps, like Google Maps or MapQuest, already collect this data by default. We believe that this information could be used to rapidly and automatically perform a type of contact tracing, helping limit the spread of COVID-19 and other infectious diseases. These phones are usually also Bluetooth-enabled, allowing them to track and record which other phones they’re in proximity to. We believe that together, these two pieces of information can be used to inform and empower our users in a range of ways. Firstly, we can generate heatmaps of high-risk areas from demographic data, known cases, and epidemiological modelling, allowing users to adjust their behaviour accordingly. Secondly, we can use Bluetooth connections between users to enact cryptographically secure contact tracing and alerting them if we learn that they have been exposed to COVID-19, without revealing the identities or infection status of any other users.