May 19, 2022

Omicron evades Moderna vaccine too, study suggests, but boosters help

The antibodies that people make after they get the standard two inoculations of the Moderna mRNA vaccine are 50 times less effective against omicron than they are against the original form of the virus, says David Montefiori, a virologist at Duke University who worked helped conduct the study.

But there was good news too. An additional 17 people in the study had received a Moderna booster. And the antibodies in their blood were highly effective at blocking the virus essentially about as effective as they are at blocking the delta variant, Montefiori says.

These findings are similar to those of studies done in labs on the blood of people who had gotten the Pfizer vaccine. Those also showed that people’s antibodies were markedly less potent against omicron.

The latest study, which has been submitted to a pre-print server but has not yet been reviewed by other scientists, involved testing antibodies in the blood of vaccinated people against a pseudovirus, which is a virus created in the lab to mimic the mutations found in the omicron variant.

Based on the findings, Montefiori says a new vaccine specifically targeting omicron probably won’t be needed. During a White House briefing Wednesday, Dr. Anthony Fauci of the National Institutes of Health echoed that, both for the Pfizer and Moderna vaccines.

Scientists are doing similar experiments testing the Johnson & Johnson vaccine alone as well as the J&J vaccine with a Pfizer booster right now, and expect to have some results by early next week.

Public health experts are alarmed by the omicron variant because it has more mutations than any previous SARS-CoV2 mutants, and appears to be the most contagious variant yet.

Originally spotted in South Africa, the variant is now spreading quickly around the globe. It has already been detected in at least 33 states in the U.S. and appears to be spreading fast. The latest CDC estimate is that omicron already accounts for about 3% of the samples the agency has analyzed, which is about a seven-fold jump from a week earlier.

The variant is already far more common than that in some parts of the country such as in New York and New Jersey area, where it’s showing up in 13% of cases, according to the CDC.

Omicron spreads so fast that it’s on track to overtake delta and become the dominant mutant in the U.S. within weeks, raising fears it could accelerate the delta surge already underway.

We could be facing very severe surges, very severe strains on our health care systems under the worst-case scenarios, says Lauren Ancel-Meyers at the University of Texas in Austin, who has been modeling the possible impact of omicron on the U.S.

Data coming out of South Africa and the UK indicate that vaccinated people can still catch the virus and can still end up in the hospital, but may not get as sick. But there are many questions about whether that would be the case in this country, where there aren’t necessarily as many people who have added protection from natural exposure to the virus.

While as a public health community we are still learning about the severity of cases caused by the omicron variant, modelling shows that even if it is less severe, the sheer number of cases that could come from a variant with the level of transmissibility that we are seeing in other countries could overrun our health care system resources, especially if it coincides with the current delta wave and flu season, says Adriane Casalotti of the National Association of County and City Health Officials.