Pfizer and Moderna have been building cases to support third shots of their respective Covid-19 vaccines but in announcing plans for such boosters beginning next month, federal health officials pointed to real-world data from ongoing studies produced independently from the company research. These studies show a decline in vaccine effectiveness, a drop-off that is more pronounced in the face of the spread of the highly transmissible delta variant.
The studies cited by federal officials spanned the elderly in nursing homes, clinicians on the pandemic frontline, and vaccinated adults whose information was housed in state databases. The research shows that the authorized vaccines continue to hold up well, keeping people from developing severe disease that requires hospitalization. But Surgeon General Vivek Murthy noted that protection against mild and moderate disease has decreased.
“Even though this new data affirms that vaccine protection remains high against the worst outcomes of Covid, we are concerned that this pattern of decline we are seeing will continue in the months ahead, which could lead to reduced protection against severe disease, hospitalization, death,” Murthy said, speaking during a Wednesday media briefing. “That is why today we are announcing our plan to stay ahead of this virus.”
Federal health officials plan to begin offering booster shots on Sept. 20 for those who have reached the eight-month mark following their second shot of the initial immunization. The decision comes less than a week after the FDA authorized booster shots for those with weakened immune systems, such as organ transplant recipients and cancer patients. The plan to offer boosters to all who have been vaccinated only covers the messenger RNA vaccines from Pfizer/BioNTech and Moderna so far. Murthy said he expects boosters will also be need for the Johnson & Johnson vaccine, which was developed as a single injection. Research is ongoing and Murthy expects data will become available in coming weeks.
Booster shots are not yet a done deal. The plan still requires the FDA to conduct an independent evaluation of the safety and effectiveness of a third dose of the mRNA vaccines. The CDC’s advisory committee on immunization practices will also review the evidence and issue recommendations about booster doses, Murthy said.
The World Health Organization is critical of the booster plans. In a separate news briefing, Bruce Aylward, senior advisor to the director-general of the WHO, said vaccinating people who have not yet been vaccinated will save more lives than giving a third shot to those who have already been immunized. COVAX, the initiative to make Covid vaccines globally available, does not yet have enough vaccine supply, Aylward said. Meanwhile, a move by one country to offer boosters will lead other countries to follow, he added.
Soumya Swaminathan, the WHO’s chief scientist, said authorization for immunocompromised patients is warranted by data, which show that a booster helps raise antibody levels. But if all high-income countries decide to offer boosters to those who are 50 and older, that would require the supply of nearly 1 billion more doses, Swaminathan said.
“Once you begin a program like that, it’s very hard to step back,” she said. “The right thing to do right now on the science side is to wait for the science to tell us when boosters, which groups of people, and which vaccines need boosters. And the second argument is a moral and ethical argument of giving people third doses when they’re already well protected, and while the rest of the world is waiting for their primary immunization.”
Rochelle Walensky, director of the Centers for Disease Control and Prevention, said the U.S. has data supporting a third dose. The state level data she cited came from a New York study conducted by analyzing four databases housing information about vaccination and cases. The ability of the vaccines to protect against infections dropped from 91.7% when the study began on May 3, to 79.8% by July 25. The decline in effectiveness against new cases of Covid-19 coincides with the rise of the delta variant, the study said.
Limitations of the New York data include the exclusion of partially vaccinated individuals and the lack of categorization by vaccine product. The study also notes that there were insufficient data to reliably estimate vaccine effectiveness in Covid-related deaths.
The nursing home data were compiled from than 85,593 weekly reports from 14,917 facilities. In March, vaccine effectiveness was 75%. As of Aug. 1, effectiveness dropped to 53%. Effectiveness estimates for the Pfizer/BioNTech vaccine were similar to the one from Moderna. However, while the effectiveness for both vaccines decreased after the delta strain become predominant, the analysis did not distinguish between symptomatic and asymptomatic presentation of the disease, the study said. Furthermore, the nursing home study did not distinguish between vaccine products, nor did it account for variables, such as age or underlying health conditions, that that could affect vaccine effectiveness. Despite early effectiveness after the vaccines were introduced, the decline in effectiveness as delta has spread in recent months led the authors to conclude that an additional dose “might be considered for nursing home and long-term care facility residents to optimize a protective immune response.”
Walensky also pointed to preliminary data from two vaccine effectiveness studies that include more than 4,000 healthcare workers, first responders, and other frontline workers in eight locations around the country. She said those data show effectiveness against symptomatic and asymptomatic infection waned from 92% prior to the emergence of the delta variant to 64% with delta.
When boosters become available, they will be provided for free regardless of insurance or immigration status, said Jeff Zients, the White House’s Covid-19 response director. He added that the U.S. has shipped more than 115 million doses to 80 countries and the government will continue to support global vaccination efforts. Those plans include an increase in manufacturing production in the U.S. and overseas.
“Our wartime effort will continue doing everything we can to get even more people vaccinated, both here at home and around world,” Zients said. “We can and must do both at the same time because that’s what it’s going to take to end this pandemic.”
COVAX has set a goal of delivering 2 billion doses by the end of 2021. As of Wednesday evening, the organization’s website said about 208 million doses have shipped so far.
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