System Feature #4: A mathematical formula to measure the Asymptomatic growth of COVID19 as well as the mechanism to control it.

The biggest reason why Coronavirus is so easy to spread in the community is that infected persons have an incubation period of about 14 days, and there are no obvious surface symptoms. Many people do not know if they have been in contact with asymptomatic .

The most effective way to tackle this problem is to use the anonymous smartphone app (or public transit card) and also to install dedicated terminals in public places such as a library, cinema, school, and gym to record where and when the people have visited. When a person is reported as virus-infected by medical authorities, the system immediately puts all persons who appear in the same place at the same time as the confirmed patient in the past 14 days into an Alert list and transmits it to all terminals. This system gives a friendly alert to potential incubators when they are entering public areas.

The mathematical formula of asymptomatic growth:

Asymptomatic Growth = (1-Participation%) x Gathering Size x Infection Rate %

Asymptomatic Growth is the growth ratio of the number of asymptomatics today over the previous day. Asymptomatic growth is a better index than infected growth to measure the spread of COVID19. Asymptomatic growth takes into consideration the daily activities and behavior of the infected people in the community.

Consistent asymptomatic growth of less than 1, indicates that COVID19 spread is under control and the daily economic activities can be resumed.

We use some figures here for ease of illustration. Assuming the average infection rate is 2% and the average size of people gathered in the public areas is 300 people, and each infected person will visit one public area on the next level in 14 days.

Block % is defined as the percentage of infected people who will be blocked by our terminals. Block % is technically the same as public participation %. It depends on various parameters: the number of terminals installed, the installed locations, and the discipline of the users.

  • Number of users in the current Alert List, Alert (0), = infected (1-Block%) x Gathering size
  • Number of users in the previous Alert List, Alert List (-1) = infected / infection rate%

Growth of Asymptomatic

Alert (0) / Alert (-1) = (1-Block%) x Gathering size x infection rate %

The overall Alert list growth can be reduced by increasing public participation such as installing more terminals. In addition, we can isolate the individual public places with high Alert list growth and then manage the 3 elements of the formula:

  • Users’ discipline
  • Gathering size: partition area with a separated terminal.
  • Infection rate: changing the way people behave.


It is the first time in the world, we can define an index, Asymptomatic Growth, to indicate if COVID19 community spreading is under control and if economic activities can be resumed.

More importantly, our system provides an executable mechanism to improve the index to a level below 1, a safety level to conduct normal economic activities.