The coronavirus variolation theory hinges on two assumptions that are difficult to prove: that lower doses of the virus lead to less severe disease, and that mild or asymptomatic infections can spur long-term protection against subsequent bouts of sickness. Experiments in hamsters have hinted at a connection between dose and disease. And those who did contract the virus became less sick than other animals without masks to protect them. That is partly because it is difficult to pin down the infectious dose required to sicken a person, Dr. Rengarajan said. And confirming the second half of the variolation theory — that masks allow entry to just enough virus to prime the immune system — might be even trickier.

Source: New York Times September 08, 2020 15:56 UTC