Third dose

Pfizer data suggest third dose of Covid-19 vaccine 'strongly' boosts protection against Delta variant

By Jacqueline Howard

A third dose of the Pfizer/BioNTech Covid-19 vaccine can "strongly" boost protection against the Delta variant -- beyond the protection afforded by the standard two doses, suggests new data released by Pfizer on Wednesday.

The data posted online, which are expected to be discussed in a company earnings call on Wednesday morning, 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.

There's "estimated potential for up to 100-fold increase in Delta neutralization post-dose three compared to pre-dose three," researchers wrote in the Pfizer data slides.

The data have not yet been peer-reviewed or published.

The data also show that antibody levels are much higher after a third dose than a second dose against the original coronavirus variant and the Beta variant, first identified in South Africa.