Pfizer Inc. and BioNTech SE said a booster shot of their Covid-19 vaccine restored full protection in a large study, results that are likely to bolster the argument for giving a third dose more widely.
A booster was 95.6% effective against symptomatic Covid in the study, which followed 10 000 people aged 16 and older, the companies said on Thursday.
Pfizer shares were 0.9% higher in premarket US trading, with BioNTech gaining 1.3% in Frankfurt.
“We believe boosters have a critical role to play in addressing the ongoing public health threat of this pandemic,” Pfizer Chief Executive Officer Albert Bourla said in a statement. The companies said they’ll share the data with health authorities in the US, Europe and elsewhere.
Regulators have wrestled with how widely to use boosters as the fast-spreading delta variant drives infection rates up. Some countries, such as Israel, are using boosters widely. Many others — including the US and much of Europe — have thus far come down on the side of a third dose for the elderly and other high-risk individuals. Exactly where to draw the line on who is high-risk has also been a matter of debate.
Half the trial participants got a booster, with five cases in that group over an average follow-up period of two and a half months. There were 109 cases in the group randomly assigned a placebo shot. The booster was just as safe as the original two-dose vaccine.
The trial results show that “booster vaccinations could play an important role in sustaining pandemic containment and a return to normalcy,” BioNTech CEO Ugur Sahin said.
Trial participants got a booster an average of 11 months after their second dose of the vaccine. They were an average of 53 years old, with slightly under one-quarter of the group older than age 65. Efficacy of the third shot was consistent across age groups and among people with pre-existing conditions, the companies said.