CDC Finally Shows The Public The Data Behind Its New Mask Guidance

The Centers for Disease Control and Prevention (CDC) released a report Friday detailing a recent COVID-19 outbreak in Provincetown, Massachusetts, which was cited by the agency as a contributing factor to its recent change in mask guidance.

Over the July 4 weekend, gatherings in Provincetown contributed to at least 900 cases, and roughly 75% of those who tested positive in the cluster were vaccinated. The Provincetown report concludes that spread among highly-vaccinated populations does occur and suggests that authorities reimplement mask mandates and other mitigation measures, even for the vaccinated.

The Provincetown report was a major warning sign for CDC officials, who earlier this week reversed course and once again recommended that vaccinated Americans wear face coverings in some indoor settings. A leaked internal document from the CDC included preliminary data from the Provincetown outbreak in its summary of information on breakthrough cases of the delta variant.