Pfizer (PFE) - Get Report said it would request U.S. emergency authorization from the Food and Drug Administration for a third booster dose of its COVID-19 vaccine, saying it could boost immunity and maybe protect against the delta variant of the virus.
Shares of Pfizer rose 0.36% in premarket trading to $39.39.
Pfizer Dr. Mikael Dolsten told the Associated Press that early data from the company’s booster study suggested people’s antibody levels jump five- to 10-fold after a third dose, compared to their second dose months earlier.
The Israeli government said its analysis has shown the Pfizer coronavirus vaccine appears to be less effective against infections caused by the delta variant compared with other strains of COVID-19, CNN reported.
"As seen in real world data released from the Israel Ministry of Health, vaccine efficacy in preventing both infection and symptomatic disease has declined six months post-vaccination, although efficacy in preventing serious illnesses remains high," said a statement from the drugmaker.
But officials at the FDA and Centers for Disease Control said they would be taking a more cautious approach, saying in a joint statement that "Americans who have been fully vaccinated do not need a booster shot at this time.
“We are prepared for booster doses if and when the science demonstrates that they are needed,” the agencies added.
Pfizer's vaccine for the coronavirus has been shown to be about 90% effective in both clinical trial and real-world studies. The vaccine produced by rival drugmaker Moderna (MRNA) - Get Report has a similar efficacy rate.
Shares of CureVac (CVAC) - Get Report declined sharply earlier this month after results from a study of the German company’s COVID-19 vaccine found it to be just 48% effective overall against the virus.