Prognosis
Pfizer Vaccine’s Effect on Transmission Still Unknown, FDA Says
- Open question could affect ongoing use of masks, distancing
- CEO says transmission data expected in 2021 first quarter
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Pfizer Inc.’s Covid-19 vaccine prevents symptomatic cases of the virus, but it’s not clear if the shot keeps the disease from being transmitted, U.S. Food and Drug Administration staff found in a report issued Tuesday.