Vaccinated people spreading Delta variant just as quickly as the unvaccinated: Leaked CDC document
The delta variant of the coronavirus appears to cause more severe illness than earlier variants and spreads as easily as chickenpox, according to an internal federal health document that argues officials must «acknowledge the war has changed». It captures the struggle of the nation’s top public health agency to persuade the public to embrace vaccination and prevention measures, including mask-wearing, as cases surge across the United States and new research suggests vaccinated people can spread the virus. The document strikes an urgent note, revealing the agency knows it must revamp its public messaging to emphasize vaccination as the best defense against a variant so contagious that it acts almost like a different novel virus, leaping from target to target more swiftly than Ebola or the common cold. It cites a combination of recently obtained, still-unpublished data from outbreak investigations and outside studies showing that vaccinated individuals infected with delta may be able to transmit the virus as easily as those who are unvaccinated.
Vaccinated people infected with delta have measurable viral loads similar to those who are unvaccinated and infected with the variant. That official told The Post that the data will be published in full on Friday. 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». It must continue to emphasize the proven efficacy of the vaccines at preventing severe illness and death while acknowledging milder breakthrough infections may not be so rare after all, and that vaccinated individuals are transmitting the virus.
The agency must move the goal posts of success in full public view. «Although it’s rare, we believe that at an individual level, vaccinated people may spread the virus, which is why we updated our recommendation,» according to the federal health official, who spoke on the condition of anonymity because they were not authorized to speak publicly. «Waiting even days to publish the data could result in needless suffering and as public health professionals we cannot accept that». The presentation came two days after Walensky announced the reversal in guidance on masking among people who are vaccinated.
The new guidance reflects a strategic retreat in the face of the delta variant. The document presents new science but also suggests a new strategy is needed on communication, noting that public trust in vaccines may be undermined when people experience or hear about breakthrough cases, especially after public health officials have described them as rare. Because public health officials had emphasized the great efficacy of the vaccines, the realization that they aren’t perfect may feel like a betrayal. «We’ve done a great job of telling the public these are miracle vaccines,» Seeger said.
The CDC’s revised mask guidance stops short of what the internal document calls for. «Given higher transmissibility and current vaccine coverage, universal masking is essential to reduce transmission of the Delta variant,» it states. The document makes clear that vaccination provides substantial protection against the virus. The document includes CDC data from studies showing that the vaccines are not as effective in immunocompromised patients and nursing home residents, raising the possibility that some at-risk individuals will need an additional vaccine dose.
The internal document contains some of the scientific information that influenced the CDC to change its mask guidance. The agency faced criticism from outside experts this week when it changed the mask guidance without releasing the data, a move that violated scientific norms, said Kathleen Hall Jamieson, director of the Annenberg Public Policy Center at the University of Pennsylvania. «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. This echoes data seen from studies in other countries, including highly vaccinated Singapore, where 75% of new infections reportedly involve breakthrough cases.
Genetic analysis of the outbreak showed that people who were vaccinated were transmitting the virus to other vaccinated people. The person said the data was «deeply disconcerting» and a «canary in the coal mine» for scientists who had seen the data. The extreme contagiousness of delta makes herd immunity a more challenging target, infectious-disease experts said. «I think the central issue is that vaccinated people are probably involved to a substantial extent in the transmission of delta,» Jeffrey Shaman, a Columbia University epidemiologist, wrote in an email after reviewing the CDC slides.
Kathleen Neuzil, a vaccine expert at the University of Maryland School of Medicine, said getting more people vaccinated remains the priority, but the public may also have to change its relationship to a virus almost certain to be with humanity for the foreseeable future. «We really need to shift toward a goal of preventing serious disease and disability and medical consequences, and not worry about every virus detected in somebody’s nose,» Neuzil said.