CDC justified new mask guidance based on vaccine study listed as failing peer review

The Centers for Disease Control and Prevention cited an unpublished study from India to justify its recommendation Tuesday that fully vaccinated people "wear a mask in public indoor settings in areas of substantial or high transmission" of COVID-19.

That study, which claimed the Delta variant produced an unusually large viral load in more than 100 vaccinated healthcare workers with "breakthrough infections," was listed as having failed peer review in the journal Nature when the CDC cited it.

Archives of the study's page on Research Square, a preprint server for unpublished research, show that it was marked "reject" on July 9 and remained so at least through the evening of July 26, Eastern Daylight Time. 

That version was still live early Wednesday morning, the day after the CDC cited the study in its July 27 updated science brief, according to a Twitter user who posted a screenshot.