Moderna says its booster shot provides good protection against Omicron

Moderna said that even a half-dose booster of its COVID-19 vaccine increased by 37 times the level of antibodies able to fight the Omicron variant.


Moderna said Monday that a booster dose of its COVID-19 vaccine should offer protection against the rapidly spreading Omicron variant of the coronavirus.

Moderna said lab tests showed that the half-dose booster shot increased by 37 times the level of so-called neutralizing antibodies able to fight Omicron.

A full-dose booster was even stronger, triggering an 83-fold jump in antibody levels, although with an increase in the usual side effects, the company said. While half-dose shots are being used for most Moderna boosters, a full-dose third shot has been recommended for people with weakened immune systems.


Moderna announced the preliminary laboratory data in a press release; the data have not yet undergone scientific review. But testing by the U.S. National Institutes of Health, announced last week by Dr. Anthony Fauci, found a similar jump in immunity.

The CDC now recommends Pfizer and Moderna’s COVID-19 vaccines over the J&J shot, citing the risk of rare blood clots.

Dec. 16, 2021

Pfizer’s testing likewise found that its COVID-19 vaccine triggered a similarly big jump in Omicron-fighting antibodies. The vaccines by Pfizer and by Moderna, both made with mRNA technology, are used by many countries around the world to fight the coronavirus.

Together, the available evidence backs health authorities’ increasing pleas for people to get their boosters as soon as they’re eligible.

Antibody levels predict how well a vaccine may prevent infection with the coronavirus, but they are just one layer of the immune system’s defenses. Other research suggests that the vaccine still should provide good protection against severe COVID-19 if people do experience a breakthrough infection.

Both Moderna and Pfizer are developing shots to better match the Omicron variant in case they’re needed.