Two newly published studies find that health workers vaccinated against Covid-19 with the Pfizer/BioNTech vaccine had lower rates of infection, especially symptomatic illness, than workers who hadn't been vaccinated. In one study, conducted in more than 6,700 health workers in Israel, only eight of the more than 5,500 fully vaccinated workers had symptomatic Covid infection, compared to 38 of the nearly 760 unvaccinated health workers who fell ill. … Another study, which looked at data from more than 5,200 workers at St. Jude Children's Research Hospital, found fewer infections — but more likely to be asymptomatic — among vaccinated workers than unvaccinated workers.