This is why.
CDC study shows three-fourths of people infected in Massachusetts covid-19 outbreak were vaccinated
By Carolyn Y. Johnson, Yasmeen Abutaleb and Joel Achenbach
https://www.washingtonpost.com/healt...ak-vaccinated/
"A sobering scientific analysis published Friday of an explosive Massachusetts covid-19 outbreak fueled by the delta variant found that three-quarters of the people who became infected were fully vaccinated. The report, from the Centers for Disease Control and Prevention, bolstered the hypothesis that vaccinated people can spread the more transmissible variant and may be a factor in the summer surge of infections.
The data, detailed in the CDC’s Morbidity and Mortality Weekly Report, provided key evidence that convinced agency scientists to reverse recommendations on mask-wearing and advise that vaccinated individuals wear masks in indoor public settings in some circumstances.
Critically, the study found that vaccinated individuals carried as much virus in their noses as unvaccinated individuals, and that vaccinated people could spread the virus to each other. The CDC was criticized this week for changing its mask guidance without citing unpublished data. The report released Friday contains that data."
The vaccine will keep you out of the hospital, but it's not going to stop the spread of Delta. Given how many people remain unvaccinated in certain places, it's a grim finding.
