Viral Exposure

This NY Times piece seems to make an important point that has not received much attention:

From a policy perspective, we need to consider that not all exposures to the coronavirus may be the same. Stepping into an office building that once had someone with the coronavirus in it is not as dangerous as sitting next to that infected person for an hourlong train commute.... 

Low-dose infections can even engender immunity, protecting against high-dose exposures in the future. Before the invention of vaccines, doctors often intentionally infected healthy individuals with fluid from smallpox pustules. The resulting low-dose infections were unpleasant but generally survivable, and they prevented worse incidents of disease when those individuals were later exposed to smallpox in uncontrolled amounts. 

Despite the evidence for the importance of viral dose, many of the epidemiological models being used to inform policy during this pandemic ignore it. This is a mistake.