Fact Check-Turnaround on CDC face mask guidance based on reduction of COVID-19 cases and vaccine efficacy

A viral tweet claims the latest change in the guidance of the U.S. Centers for Disease Control and Prevention (CDC) for fully vaccinated people is proof that the COVID-19 pandemic is a lie. This allegation is untrue: the update, which allows people who have been fully vaccinated to ditch their face masks in most places, was based on scientific evidence and healthcare milestones cited by CDC Director Rochelle Walensky.

“You guys do know that the CDC lifting those guidelines out of the blue with no solid explanation proves they lied to you the whole time about everything, right? Just want to make sure everyone has processed that correctly,” reads the tweet ( here ), retweeted almost 10,000 times as of the publishing of this article. It has also been replicated on Facebook, gaining at least 3,000 shares ( here , here , here , here ).

On May 13, the CDC updated previous guidance to say fully vaccinated people do not need to wear masks outdoors and can avoid wearing them indoors in most places ( here ). People are fully vaccinated two weeks after their second dose of Pfizer or Moderna vaccines or two weeks after a single-dose vaccine such as Johnson & Johnson’s Janssen shot ( here ).

The change did cause confusion among some Americans ( here ) but the claim that there was “no solid explanation” for it is false.

“Although it is true that how quickly the CDC reversed (previous advice) caught some of us by surprise”, there’s substantial evidence behind this update, Mark Roberts, professor and former chair of the University of Pittsburgh Graduate School of Public Health’s Department of Health Policy and Management ( here ) told Reuters via phone.

Likewise, Lisa L. Maragakis, Senior Director of Infection Prevention at Johns Hopkins Health System ( here ) noted in an emailed statement to Reuters that the new guidance “was issued based on scientific evidence showing the efficacy of the COVID-19 vaccines to protect those who are fully vaccinated.”

When announcing the update, CDC Director Rochelle Walensky said the update was based on a sharp reduction in cases ( here ) in the country, expansion of vaccines to younger people ( here ) and vaccine efficacy against coronavirus variants ( here ).

An increasing amount of evidence is also suggesting that the risk of onward transmission of the virus from fully vaccinated people is low, Roberts explained.

For example, a report ( here ) in Nature showed that people who received at least one shot of the Pfizer/BioNTech vaccine and later became infected by the coronavirus had significantly lower viral loads, or levels of virus, than unvaccinated people. Higher viral loads are associated with being more contagious.

“The other stream of evidence that has come out, that was not known a month ago, was how effective are the vaccines at preventing the spread of these new variants,” Roberts added. ”The evidence that’s accumulating again from Israel, United States and Britain, is that even the variants are relatively well protected by the vaccine.”

The announcement also comes when more than 47% of the country’s population has received at least one dose of a COVID-19 vaccine, and about 37% had been fully vaccinated as of May 16, according to the CDC ( here ). A Reuters explainer here lays out the latest scientific evidence used by the CDC to back the decision.


False. The CDC’s May 13 mask update for fully vaccinated people is not proof that the COVID-19 pandemic is a lie. The CDC cited a decrease of cases, expanded vaccine access for younger people and growing evidence about vaccine efficacy against variants as reasons for the revised guidance.

This article was produced by the Reuters Fact Check team. Read more about our work to fact-check social media posts here .