How do you know if you need a Covid-19 Booster Shot?

Amid persistent concerns that the protection offered by COVID-19 vaccines may be waning, a report released Friday by the Centers for Disease Control and Prevention finds that America's workhorse shot is significantly less effective at preventing severe cases of disease over the long term than many experts had realized. Data collected from 18 states between March and August suggest the Pfizer-BioNTech vaccine reduces the risk of being hospitalized with COVID-19 […]