Asymptomatic and Symptomatic SARS-CoV-2 Infections After BNT162b2 Vaccination in a Routinely Screened Workforce

Letter describes observational study which found receipt of the Pfizer BioNTech Covid-19 vaccine by hospital workers was associated with a lower incidence of symptomatic (IRR 0.16; 95% CI, 0.10-0.25) and asymptomatic (0.28; 95% CI 0.18-0.42) Covid-19 infection.

SPS commentary:

The authors acknowledge the numerous limitations of their observational research, some of which may have biased the results in favour of vaccination, and say that further research is needed to determine whether a reduction in the risk of asymptomatic infection results in reduced transmission. 

Journal of the American Medical Association