Moderna says booster shot of its COVID-19 vaccine should protect against Omicron

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 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.

Moderna announced the preliminary laboratory data in a mediarelease and it hasn't yet undergone scientific review.

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.

But testing by the U.S. National Institutes of Health, announced last week by Dr. Anthony Fauci, found a similar jump.

Pfizer's testing found its COVID-19 vaccine triggered a similarly big jump in omicron-fighting antibodies.

Pfizer and BioNTech said earlier this month that two vaccine doses of their vaccineresulted in significantly lower neutralizing antibodies, but that a third dose of their vaccine increased the neutralizing antibodies by a factor of 25.

Blood obtained from people who had their third booster shot a month ago neutralized the Omicron variant about as effectively as blood after two doses fought off the original coronavirus.

At the time, the companies had stressed their findings are"preliminary," with more research and real-world effectiveness data needed to inform the best path forward.

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, including Canada.

Antibody levels predict how well a vaccine may prevent infection with the coronavirus but they are just one layer of the immune system's defences.

Other research suggests the vaccine still should induce good protection against severe disease 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.