Duke study: Moderna vaccine less effective against omicron variant, but booster helps

Nandini Kumar, 33, of Duke Primary Care administering a dose of the COVID-19 vaccine to Teofilo Dasilva, 69, of Raleigh.

Nandini Kumar, 33, of Duke Primary Care administering a dose of the COVID-19 vaccine to Teofilo Dasilva, 69, of Raleigh.

The standard two doses of the Moderna vaccine appear to be far less effective against the new omicron variant of the coronavirus, but a booster shot seems to make up the difference.

That’s the result of a study conducted by researchers at Duke University and the National Institutes of Health and released Thursday. The results mirror those of a similar study involving the Pfizer vaccine released earlier this week.

The Duke and NIH study used blood samples of people who received the Moderna vaccine as part of previous clinical trials. Researchers measured how the coronavirus antibodies in the blood responded to the omicron variant.

They found that the antibodies were 50 times less likely to neutralize omicron compared to the original form of the virus that emerged in early 2020, said Dr. David Montefiori, whose lab at Duke conducted the research.

“That’s the bad news,” Montefiori told The News & Observer. “The good news is that if you get the boost, the levels go up to where they are against the delta variant after two doses. And we know that two doses of the vaccine are very effective against delta.”

The omicron variant was first reported in South Africa in November, and scientists have been scrambling since then to determine whether it will evade the vaccines that hundreds of millions of people have received around the world.

Tests involving blood samples offer an early indication that standard doses of Pfizer and Moderna vaccines are far less effective, Montefiori said. But scientists won’t know for sure how much more likely it is vaccinated people will get infected or sick until they can gather data from people in hospitals and doctors’ offices.

“You always need clinical data, which is harder to get, to confirm things,” he said.

One such study from South Africa released this week found that people who received two doses of the Pfizer vaccine had a 70% chance of avoiding being hospitalized with the omicron variant of COVID-19. That compared to a 93% chance of avoiding hospitalization from an infection with the delta variant.

“If you’re 70% less likely to be hospitalized, that’s still pretty good odds,” Montefiori said. “And after a boost, that might go back up to the high 90% for hospitalization. That’s what our data would indicate.”

Duke and NIH scientists are continuing to test blood samples to determine how antibodies perform against omicron in people who received some combination of vaccines. Public health officials have said it’s OK for people to receive a booster of a different vaccine than the one they received the first time.

More than 2 million booster doses of vaccine have been administered in North Carolina, according to the state Department of Health and Human Services. That’s about a third of the more than 6 million people who received two doses of the Pfizer or Moderna vaccine or the single dose Johnston & Johnston vaccine.

The first confirmed case of the omicron variant in North Carolina was in a UNC Charlotte student last week. The variant appears to pass more easily from one person to another, but early indications are that it generally causes less severe illness than other variants.

That higher infection rate is another reason for getting vaccinated, Montefiori said.

“For people who still haven’t been vaccinated and have been fortunate enough not to get infected so far, with omicron their luck is running out,” he said. “It’s so much more contagious that it is going to be harder to avoid getting infected with it.”

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Richard Stradling covers transportation for The News & Observer. Planes, trains and automobiles, plus ferries, bicycles, scooters and just plain walking. Also, hospitals during the coronavirus outbreak. He’s been a reporter or editor for 34 years, including the last 22 at The N&O. 919-829-4739, [email protected]


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