Booster Approaches for Pfizer/BioNTech Vaccine

Feature image: BioNTech production facility in Marburg, Germany.

Pfizer and BioNTech have uncovered the threat but have the cure in hand, according to a media statement released by the two companies late last week. Efficacy data for the company’s planned booster shot, they report, is expected to be submitted for approval to European and North American regulatory authorities “in the coming weeks.”

An earlier study has shown that individuals vaccinated with the Pfizer shot can neutralise the delta variant of the coronavirus. However, it appears the vaccine either becomes less effective with time, or is less effective against the delta variant, which has been heading to world dominance since the Indian outbreak.

That efficacy data comes from real-world observations made by the Israeli Ministry of Health. Israel and Australia were offered advanced access to the Pfizer vaccine in exchange for ongoing efficacy data, but Israel was the country that managed to close the deal.

Now, six months after most Israelis have been vaccinated, vaccine efficacy in preventing symptomatic Covid-19 has fallen from 94% to 64% (the vaccine remains effective in limiting severe symptoms and hospitalisation). It is not clear whether this is due to the passage of time, or the mutations carried by the delta variant of the coronavirus.

Against these dire findings, there is hope in the prospect of a Pfizer booster shot. Studies have shown that a booster shot, given six months after the second shot, provokes a remarkable antibody response, five to 10 times higher than what is elicited after the second shot.

There is reportedly no data as yet for the specific efficacy of the booster shot against the delta variant. “The companies anticipate that a third dose will boost those antibody titers even higher, similar to how the third dose performs for the Beta variant (B.1.351),” said Pfizer and BioNTech in the statement.

In other words, the race between viral evolution and vaccine developers continues. But the India outbreak has shown that the more unvaccinated population there is amongst whom the virus can circulate, the more dangerous it will become.

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