Despite being 95 percent effective in preventing coronavirus infection after two doses of its vaccine, Pfizer is already seeing what a third dose can do.
The company announced Thursday that a booster dose is being studied among people who received their first doses of the vaccine more than six months ago.
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In an interview with NBC News’ Leicester Holt, Pfizer CEO Albert Burla said he hoped a third dose would boost the immune response even more, offering better protection against options.
“We believe that the third dose,”
The new study will look at the safety and efficacy of a third dose in two age groups: 18 to 55 and 65 to 85. Participants came from a group of people who were among the first to receive the Pfizer-BioNTech vaccine: people who volunteered for the initial clinical Pfizer’s Phase 1/2 trial, which began in May.
During this study, participants received two doses of the vaccine at three-week intervals. The same dosing interval is what is currently recommended.
The third shot will be exactly the same as the one the participants received a year ago.
Pfizer also plans to begin testing whether a modified version of the vaccine works well against the South African version.
In fact, as SARS-CoV-2 changes, vaccines may need to be changed. The Food and Drug Administration issued guidelines Monday saying vaccine manufacturers may be able to avoid lengthy clinical trials to prove the safety and effectiveness of vaccines that have been modified to account for variants.
This is no different from how the flu vaccine changes from year to year, taking into account the strains that are most likely to infect humans.
“You have to go every year to get the flu vaccine,” Burla said. “It will be the same with Kovid. In a year, you will have to go and get your annual shot for Kovid to be protected.”
This suggests that even when the pandemic is over, Covid-19 may be here to stay. Ongoing studies of processed vaccines are needed to understand when boosters may be needed, external experts said.
“You have to cast a wide net to find Goldilocks,” said John Grabenstein, a former executive director of vaccine medicine at Merck and a former immunologist at the Department of Defense. “You want to look at shorter intervals, you want to look at longer intervals to determine when is the best time, if necessary, for revaccination.”
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So far, data show that the existing Pfizer-BioNTech vaccine remains effective against variants first identified in the UK, Brazil and South Africa.
Burla said the company’s goal, if and when another option emerges, is to rotate and change the current vaccine within 100 days.
Moderna, which produces a similar vaccine, Covid-19, said Wednesday it has also begun studying the effects of adding a third dose to its regimen and has developed a version of the vaccine designed to target the South African variant.
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