74 Percent of COVID-19 Cases From Massachusetts Outbreak Occurred in Fully Vaccinated People: Study

Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, adjusts her face mask during a Senate hearing in Washington on March 18, 2021. Susan Walsh/AP Photo

A COVID-19 outbreak in a Massachusetts county in July primarily occurred among vaccinated people, sparking fears that a variant of the CCP virus can impact that population more than other strains.

Of the 469 cases detected in Barnstable County, 74 percent occurred among the fully vaccinated, according to a new study published on Friday.