The company also said it plans to start clinical trials in August of an updated version of its vaccine that would better protect against the Delta variant.
Pfizer and partner
said Thursday that they will seek authorization for the third shot, based on encouraging initial study data.
The companies said the data showed that a booster shot given at least six months after the second dose produced antibodies protective against the original strain of the virus and a more recent strain, Beta.
The companies said the antibody levels were five to 10 times higher than after two doses.
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The companies said they expect their third booster shot to provide similar higher levels of protection against the Delta variant.
In addition, Pfizer and BioNTech said they have begun producing the updated vaccine for testing in people.
“While we believe a third dose of BNT162b2 has the potential to preserve the highest levels [of] protective efficacy against all currently known variants including Delta, we are remaining vigilant,” the companies said, using the code name for their original vaccine.
The moves are the strongest sign to date of vaccine makers’ efforts to confront new variants of the virus better able to elude existing shots.
To date, companies have been evaluating the effectiveness of their shots against new variants and working on boosters and new vaccines targeting the strains.
Pfizer and BioNTech are the first to say they will ask regulators to authorize a booster that could increase their vaccine’s protection against the strains.
The Pfizer-BioNTech vaccine was the first to be authorized in the U.S., and has been cleared for use in people 12 years and older.
Studies have indicated the shot protects well against new variants of the virus that have emerged since the companies began developing their original version, especially after the second dose.
The vaccine doesn’t offer as much protection after the first of two doses, however. And the company said that it appears the vaccine’s effectiveness begins to wane about six months after the second dose, based on its own clinical trials and recent data released by the Israeli Ministry of Health.
Israel said earlier this week that the shot protected 64% of inoculated people from infection during an outbreak of the Delta variant, down from 94% before.
The vaccine still provided 94% protection against severe illness during the outbreak, compared with 97% before, the health ministry said.
The Delta variant was first identified in India, where cases caused by the strain overwhelmed the country’s hospitals.
Since then, it has spread rapidly around the globe, including in the U.S.
This week, federal health officials said it was now the most common strain in the U.S.
The variant appears more contagious than earlier versions of the virus and better able to evade vaccines.
Health authorities have encouraged people to get vaccinated to better ward off the Delta variant, saying more than 99% of Covid-19 deaths in the U.S. are among the unvaccinated.
Write to Joseph Walker at email@example.com
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