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

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

And 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.

Also read: Omicron may sideline two leading drugs against COVID-19

Moderna announced the preliminary laboratory data in a press release and it hasn’t 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.

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

Also read: WHO: Omicron detected in 89 countries, cases doubling fast