Some scientists and officials in the CDC disagree with the data that influenced the agency's recent recommendations that both vaccinated and unvaccinated people should wear masks again indoors in areas with high levels of COVID-19 transmission, The Wall Street Journal reported Aug. 3.
The CDC released new guidance July 27 recommending that fully vaccinated Americans start wearing masks again indoors in U.S. regions where COVID-19 transmission is high; the recommendations came about two months after the agency said fully vaccinated Americans no longer needed to wear masks or follow social distancing guidelines in most indoor settings.
For its latest recommendations, the CDC cited data from Provincetown, Mass., where it said large gatherings in July at bars, nightclubs and parties drove hundreds of COVID-19 infections. The analysis found that nearly three quarters of infected people were fully vaccinated, and samples showed that the amount of virus infected people carried, or viral load, was similar between vaccinated and unvaccinated patients, according to the report.
Based on the findings, the CDC concluded that vaccinated people who become infected might spread the delta variant as readily as the unvaccinated — a conclusion with which some officials in the CDC disagree, a person familiar with the matter told the Journal. Some scientists also have said the Provincetown study isn't reliable enough to be the leading cause of public health policy change, the Journal reported.
The Provincetown data also is too recent to be independently reviewed by outside experts and is too small a sample with too unique of circumstances surrounding the outbreak for it to be applied to other parts of the country, according to the scientists who criticized the decision.
"They're making these decisions on the basis of extremely weak and unreliable data, and at the same time not doing the necessary work to reduce uncertainty among the population," Vinay Prasad, MD, an epidemiology professor at the University of California San Francisco, told the publication. "When there isn’t a lot of study data, the CDC should be conducting these studies."
The CDC's July 27 guidance applied to areas with high transmission of the virus, which tend to be parts of the country with lower vaccination rates. At the time of the analysis in Provincetown, vaccination rates were high, around 69 percent of eligible Massachusetts residents, according to the report.
The CDC did not return the Journal's comment requests.