The Centers for Disease Control and Prevention has changed its guidance once again to recommend that fully vaccinated persons continue to wear masks in certain situations.

Apparently, this reversal was made out of concern for the delta variant, which appears to be more transmissible, though not at all more deadly. That last part is key: Vaccinated persons are not falling seriously ill or dying from the delta variant because the vaccines work. Out of the tens of millions of people who have been vaccinated against COVID-19, less than 0.037% have been hospitalized with the virus. So, vaccinated persons are at no more risk of dying from the coronavirus or one of its many variants than they were 18 days ago when the CDC agreed that vaccinated teachers and students don’t need to wear masks. The science has not changed, but the CDC’s risk assessment has.