Health officials in the United States will on Friday explain the science behind their u-turn on face masks, as Republicans express skepticism over the decision - which appears to have stemmed from research into a July 4 outbreak.
The Centers for Disease Control and Prevention (CDC) on Tuesday announced that they were updating their previous guidance to now recommend the wearing of face masks once more, when indoors and in parts of the country with substantial COVID-19 transmission.
They did not explain their reason for the shift in policy, and merely said it was due to new data on the highly contagious Delta variant. On May 13 the American public was told they no longer needed to wear masks indoors.
An internal federal health document obtained by The Washington Post explained the new data, and reported that the Delta variant was as infectious as chickenpox or Ebola.
Officials, the document stated, must 'acknowledge the war has changed.'
Dr Rochelle Walensky, the director of the CDC, has said that they will publish the science behind their decision, announced on Tuesday, on Friday. The CDC has faced some criticism for announcing new recommendations on face masks without providing the science behind their decision
The slide presentation said that the CDC must improve its messaging on COVID-19, and emphasize the urgency of the situation.
'I finished reading it significantly more concerned than when I began,' said Robert Wachter, chairman of the Department of Medicine at the University of California at San Francisco.
Dr Rochelle Walensky, director of the CDC, said that the new data - to be published on Friday - showed that vaccinated people infected with the Delta variant carry tremendous amounts of the virus in the nose and throat.
Walensky told The New York Times that the data suggest that even fully immunized people can be unwilling vectors for the virus - a change from the previously-held belief that vaccinated people were unlikely to increase the spread of COVID-19.
Walensky privately briefed members of Congress on Thursday, drawing on much of the material in the slide presentation obtained by The Washington Post.
Walensky is pictured on July 20 testifying before Congress. She briefed Congress on the new scientific findings on Thursday, and on Friday will make the results public
'I think people need to understand that we're not crying wolf here. This is serious,' she told CNN.
One of the slides states that there is a higher risk among older age groups for hospitalization and death relative to younger people, regardless of vaccination status.
Another estimates that there are 35,000 symptomatic infections per week among 162 million vaccinated Americans.
The document outlines 'communication challenges' fueled by cases in vaccinated people, including concerns from local health departments about whether coronavirus vaccines remain effective and a 'public convinced vaccines no longer work/booster doses needed.'
The CDC was criticized this week for updating the mask guidance without detailing the science behind it.
Kathleen Hall Jamieson, director of the Annenberg Public Policy Center at the University of Pennsylvania, told The Washington Post that their move violated scientific norms.
'You don't, when you're a public health official, want to be saying, 'Trust us, we know, we can't tell you how,' Jamieson said.
'The scientific norm suggests that when you make a statement based on science, you show the science.
'And the second mistake is they do not appear to be candid about the extent to which breakthroughs are yielding hospitalizations.'
