'Significant increase' in protection vs Omicron from mRNA boosters, study says

Reuters

Published Dec 22, 2021 14:24

COPENHAGEN (Reuters) - Getting a third dose of either Pfizer-BioNTech's or Moderna (NASDAQ:MRNA)'s COVID-19 vaccine offers a "significant increase" in protection against the Omicron variant in elderly people, according to a Danish study published on Wednesday.

The study, which is not yet peer-reviewed, investigated the effectiveness of COVID-19 vaccines that use so-called mRNA technology against the Delta variant and the new, more infectious Omicron variant.

"Our study contributes to emerging evidence that BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) primary vaccine protection against Omicron decreases quickly over time, with booster vaccination offering a significant increase in protection," the authors wrote in the study.

The study was conducted by researchers at Denmark's top infectious disease authority, Statens Serum Institut (SSI). It analysed data from three million Danes gathered between Nov. 20 and Dec. 12.

Among those who recently had their second vaccine dose, effectiveness against Omicron was measured at 55.2% for Pfizer-BioNTech and 36.7% for Moderna, compared to unvaccinated people.

But that protection quickly waned over the course of five months, the researchers said.

"We see that the protection is lower and decreases faster against Omicron than against the Delta variant after a primary vaccination course," study author Palle Valentiner-Branth said.

However, a third dose of Pfizer-BioNTech's vaccine restored protection to 54.6% in people aged 60 or more who had been inoculated 14 to 44 days earlier, compared to those with only two doses.