COVID-19: Viral Load.

There is increasing evidence coming out of research that the amount of viral load you get of COVID-19 affects how badly you are affected by the virus.

So for instance a minimal passing contact with an infected person may only allow the minimum of viral particles to enter your system. Or possibly touching a surface with already weakened virus on it.
In this instance you may only suffer mild effects of the virus. There isn't enough viral load to overwhelm your immune system.

However, if you are exposed to a large dose of viral particles for an extended period, then there is a higher chance you will be affected severely by the virus.

So, the watchword is stay alert: make sure you keep your distance from people, make sure any contact is fleeting and wear a decent mask.

Avoid sitting in close proximity to people outside your close family group for extended periods of time, especially indoors.

When indoors in stores, keep your distance and make any close proximity fleeting.

Common sense really.