The study found that ¾ of the cases occurred in fully vaccinated individuals.
On Friday, the United States Centers for Disease Control and Prevention released a study documenting COVID-19 breakthrough infections that were associated with large public gatherings in Barnstable County, Massachusetts.
The study discusses 469 cases of COVID-19 during July that were linked with multiple summer events.
During this time, vaccination coverage among eligible residents of the state was at 69%, one of the highest rates in the country.
Among the 469 documented cases, 346 (74%) occurred in fully vaccinated individuals. Genomic sequencing of specimens from 133 of those cases demonstrated that 119 (89%) of them were found to be the Delta variant.
Symptomatic cases were seen in 274 (79%) of the vaccinated individuals and 4 ended up needing to be hospitalized.
The study also found that vaccinated individuals carried as much virus in their noses as those who are unvaccinated.
These findings show just how highly transmissible the Delta variant of the SARS-CoV-2 virus really is. The CDC stated that it is crucial to understand the determinants of transmission in order to develop prevention strategies.
The data reported in the study is what led to the CDC recently reversing course and again recommending that vaccinated individuals begin wearing masks in areas where there is a high transmission rate of COVID-19.
“This finding is concerning and was a pivotal discovery leading to CDC’s updated mask recommendation,” Rochelle Walensky, director of the CDC said in a statement. “The masking recommendation was updated to ensure the vaccinated public would not unknowingly transmit virus to others, including their unvaccinated or immunocompromised loved ones.”