People who have been fully vaccinated for COVID-19 yet still get infected with the delta strain could transmit the infection to unvaccinated people, Centers for Disease Control and Prevention Director Rochelle Walensky said Tuesday in justifying renewed recommendations for mask-wearing.
“In rare occasions, some vaccinated people infected with the delta variant after vaccination may be contagious and spread the virus to others,” she told reporters on Tuesday. “This new science is worrisome and unfortunately warrants an update to our recommendations.”
Previous recommendations from the agency were based on COVID-19 monitoring data that indicated vaccinated people rarely transmit the virus to others. The delta variant, however, is believed to be about twice as transmissible as the original strain of COVID-19, typically referred to as the “wild type” strain, and is sweeping through largely unvaccinated clusters of people and threatening to overwhelm hospital systems.