Pfizer data suggest third vaccine dose boosts immunity against Delta variant

A third dose of the Pfizer/BioNTech COVID-19 vaccine can “strongly boost" protection against the Delta variant, suggests initial data released by Pfizer.

The company posted slides ahead of an earnings call (page 25) suggesting that a booster dose of the current vaccine, given >6 months after the second dose, could increase the protection afforded by the standard two doses when it comes to the Delta strain.

The data suggest that antibody levels against the Delta variant in people ages 18 to 55 who receive a third dose of vaccine are greater than five-fold than following a second dose. Among people ages 65 to 85, the Pfizer data suggest that antibody levels against the Delta variant after receiving a third dose of vaccine are greater than 11-fold than following a second dose. The data have not yet been peer-reviewed or published.

Pfizer announced earlier this month that it would be applying for FDA emergency use authorization for a third dose of its vaccine. According to the drugmaker, discussions with regulatory agencies are ongoing and Pfizer could potentially submit a EUA application as early as August.

Pfizer is also reportedly working on a Delta variant vaccine. According to the drugmaker's update, it already has the first batch manufactured and clinical studies are projected to begin in August.