The Moderna vaccine, for example, “is highly effective in preventing symptomatic COVID.” They only did PCR testing on trial participants who reported symptoms.

The Moderna vaccine, for example, “is highly effective in preventing symptomatic COVID.” They only did PCR testing on trial participants who reported symptoms. They did not PCR test the entire study population. Incidence of symptomatic COVID was dramatically halted by about Day 14 after the first dose: https://twitter.com/wgibson/status/1336298050315313158?s=21 https://twitter.com/wgibson/status/1336298050315313158?s=21