The delta coronavirus variant, first detected in India, appears to be as contagious as chickenpox and appears to cause more severe illness than earlier strains, according to an internal CDC slide presentation obtained by The Washington Post.
The internal report, dated July 29, says next steps for health officials include to "acknowledge the war has changed" against COVID-19.
Seven things to know:
1. The presentation says delta, the dominant U.S. strain, appears to be more transmissible than the viruses that cause MERS, SARS, Ebola, the common cold, seasonal flu and smallpox.
2. The report says vaccinated people infected with delta have had similar viral loads as unvaccinated people infected with the strain, which suggests vaccinated people may spread the virus just as easily as those who are unvaccinated — findings based on still unpublished data from studies and outbreak analyses.
3. This preliminary data is part of what led the agency to tighten mask guidance for everyone, regardless of vaccination status. The guidance, updated July 27, urges people in areas of high transmission to mask up indoors.
4. Critics have said the CDC's move to update mask guidance without publishing the data the decision was based on contributes to public mistrust and vaccine hesitancy, the Post reports.
"Although it's rare, we believe that at an individual level, vaccinated people may spread the virus, which is why we updated our recommendation," a federal health official who spoke on the condition of anonymity told the publication. "Waiting even days to publish the data could result in needless suffering, and as public health professionals we cannot accept that."
5. The data is expected to be published in full July 30, an official told the Post.
6. The internal CDC report also referenced "communication challenges" related to public messaging. "Public convinced vaccines no longer work/booster doses needed," the document says. "Important to update communications describing breakthrough cases as 'rare' or as a 'small percentage' of cases."
7. While breakthrough infections are expected, vaccinated people have a 25-fold reduction in risk of death, a 25-fold reduction in risk of hospitalization, and an eightfold reduction in risk of disease, Scott Gottlieb, MD, former FDA commissioner said, citing data from the CDC document.