4th COVID vaccine dose significantly boosts immunity, UK study finds – POLITICO

LONDON — A fourth dose of an mRNA vaccine significantly boosts the immune protection from the coronavirus in all ages, according to new research published Tuesday in the Lancet Infectious Diseases journal.

Researchers tested the antibody and cellular immune responses in people who had previously had three doses of the BioNTech/Pfizer vaccine and those who had received two doses of the Oxford/AstraZeneca jab plus a third shot with BioNTech/Pfizer.

Half the people in each group were given another Pfizer jab, the others were given the Moderna half-dose booster, around 30 weeks after their third shot.

Results from the extended COV-BOOST study found that those who received the Moderna jab saw the highest boost to their immunity with around a 16-fold increase compared with before the fourth shot.

Also, compared with 28 days after their third jab (when the immune response is highest), the Moderna booster on average more than doubled the level of antibodies against the spike protein.

There was also a significant boost to immunity with a fourth dose of the BioNTech/Pfizer jab. Antibody levels increased on average 12-fold compared with before the dose, and by more than one-and-a-half times compared with 28 days after their third shot.

The data also hint at a ceiling of antibody levels from boosting with both mRNA vaccines, the researchers found.

The results come as countries continue to expand their booster programs to older and more vulnerable groups, in whom waning protection poses greater risks.

While the European Medicines Agency has endorsed a fourth dose in vulnerable and immunocompromised people, no vaccines have yet been authorized as a second booster in the general population.

Asked during a press briefing Monday whether the data supported boosting wider populations, Saul Faust, COV-BOOST chief investigator, said that decision would be for immunization committees and will be based on rates of hospitalizations and severe disease among those who’ve received two and three doses, as well as emerging variants.

He said current vaccines were continuing to protect people well from severe disease, even in people who have received three doses of the AstraZeneca vaccine, which has shown to generate lower antibody levels.

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