Second booster shields elderly from Covid-19 but protection wanes quickly: Study

A vial of the Pfizer vaccine against the coronavirus disease (Covid-19) is seen as medical staff are vaccinated at Sheba Medical Center in Ramat Gan, Israel on Dec 19, 2020. A fourth dose of the Pfizer/BioNTech vaccine lowered rates of Covid-19 among the elderly but the protection against infection appeared short-lived, a large study in...