House Minority Leader Kevin McCarthy (R-Calif.) says the CDC’s recent “masks on again” guidance is based on an unpublished study that not only evaluated the efficacy of a COVID-19 vaccine that’s “not approved in America”, but also failed peer review.
Archives of the unpublished study’s page on Research Square show that from July 9 through July 26, it was marked “Reject after peer review.” On July 27, not long after the CDC issues it’s “masks on again” guidance, the July 9 note had been changed to read “Revise.”

The CDC’s July 27, 2021 “fully vaccinated guidance” web page (link below) appears to confirm that the “masks on again” guidance was based on this unpublished, rejected then not rejected study about vaccines not approved in America. In one place, it says the new guidance is based on “new evidence on the B.1.617.2 (Delta) variant currently circulating in the United States.” Later, it refers to “unpublished data” from studies done in India “with vaccines not authorized for use in the United States.”
But on the CDC’s July 27, 2021 “fully vaccinated people” page (link below), the lead paragraph strongly suggests the “masks on guidance” is not justified by existing data. “Studies published since the last update that demonstrate currently authorized mRNA vaccines provide protection against variants of concern, including the Delta strain that is now predominant in the United States. Vaccine effectiveness against hospitalization and death is high for all current SARS-CoV-2 variants; emerging data suggest lower effectiveness against confirmed infection and symptomatic disease caused by the Beta, Gamma, and Delta variants compared with the ancestral strain and the Alpha variant.”

Nate Silver did a deep dive into what the CDC report on the Provincetown outbreak says. Some are using it to justify the new mask mandate. Mainly, Silver notes that the sample size was both tiny (~200) and also non-diverse (mostly affluent middle-aged gay men). IOW, the data simply isn’t meaningful beyond that single event.
- https://justthenews.com/politics-policy/coronavirus/cdc-justified-new-mask-guidance-based-vaccine-study-listed-failing-peer
- https://web.archive.org/web/20210726050158if_/https://www.researchsquare.com/article/rs-637724/v1
- https://twitter.com/angrybklynmom/status/1420391384423489545
- https://www.theepochtimes.com/mkt_breakingnews/cdc-new-mask-guidance-based-on-vaccine-not-approved-in-america-gop-leader_3924307.html
- https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated-guidance.html
- https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/fully-vaccinated-people.html
- ‘…seems like quite a stretch’: Nate Silver breaks down the CDC data from Provincetown, MA that’s being used to justify the new mask guidance – twitchy.com
- Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021 | MMWR (cdc.gov)