Study Reveals Declining COVID-19 Vaccine Efficacy Against Infection

Today’s report tracked the cohort through August 14—incorporating over four more months of data that include a time period in which the Delta variant swept the country—and found that overall, vaccine effectiveness dipped to 66 percent in the weeks when the variant accounted for at least 50 percent of SARS-CoV-2 viruses sequenced. What the study can’t answer is why effectiveness dipped in the weeks dominated by Delta.

Study Reveals Declining COVID-19 Vaccine Efficacy Against Infection

The vaccines remain protective against serious disease and death.