The protection offered by Covid-19 vaccines appears to wane over time, especially for people 65 and older, an expert from the U.S. Centers for Disease Control and Prevention said on Wednesday.
Ruth Link-Gelles, who helps lead the CDC’s vaccine efficacy team, looked at a series of studies examining the overall effectiveness of vaccines in various groups between February and August and found similar patterns for the vaccines. from Pfizer and Moderna, both made using mRNA.
The results tended to support the argument that people’s protection starts to weaken after a few months and that boosters might help restore their immunity.
Efficacy began to decline a few months after people were fully immunized – defined as two weeks after their second dose of either vaccine.
“For people 65 years of age and older, we saw a significant drop in EV (vaccine efficacy) against infection during Delta for mRNA products,” Link-Gelles said at an advisers meeting in vaccines from the CDC.
âWe’ve also seen declines, especially for Pfizer, for 65 and over, which we don’t see in younger populations. Finally, there is evidence of a decline in VE versus hospitalization in the Delta period, âshe said.
The CDC’s advisory committee on immunization practices met on Wednesday to discuss the potential need for vaccine booster doses.
Later Wednesday, the United States Food and Drug Administration granted Pfizer an emergency use authorization for the boosters in people 65 years of age and older, those with underlying conditions that put them at risk. severe illness and for people whose work puts them at high risk of exposure.
ACIP will meet today to discuss the FDA’s EUA and issue its own recommendations on how it should be applied to the American population. The CDC director must then approve these recommendations. They will currently only apply to Pfizer’s vaccine.
Link-Gelles said that, overall, the efficacy of Moderna’s vaccine is superior to that of Pfizer. For the Johnson & Johnson vaccine, the effectiveness of the vaccine actually increases over time, even after the Delta variant has dominated.
A study called SUPERNOVA looked at veterans between February and August of this year. In that study, the Pfizer vaccine provided 92% protection against hospitalization for those 18 to 64 and 77% for those over 65, Link-Gelles said. The Moderna vaccine provided 97% protection against hospitalization for those aged 18 to 64 and 87% for those 65 and over. Efficiency does not appear to be affected by the arrival of the Delta variant, according to the study.
A study called IVY looked at adults hospitalized in 18 states between March and August. The effectiveness of Pfizer’s vaccine increased from 91% 14 to 120 days after full vaccination, to 77% three months or more after full vaccination. The effectiveness of Moderna’s vaccine did not significantly decrease, remaining at 92% or 93% in this study.
In a study of 4,000 healthcare workers, first responders and other frontline workers in eight locations that were tested weekly for any symptoms, vaccine protection against any infection increased from 91% before Delta to 66% during Delta.
Pfizer told ACIP that it hopes and expects antibody protection from a third dose of its Covid-19 vaccine to last longer than after the initial two doses, but more research will be needed to determine if additional doses would be needed later.
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