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Moderna COVID booster: How well does it work against omicron?

Moderna’s half-dose booster shot has shown a 37-fold increase in antibodies against omicron.
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Recent research demonstrates that existing COVID-19 vaccines offer less defense against the surging omicron variant and that booster shots increase that protection. A Lancet study in early December found that the Moderna booster protected best — raising antibodies 32 times in those previously vaccinated with Oxford/AstraZeneca — though it also had the most adverse effects.

However, a report from the UK on Friday indicates that booster effectiveness starts to decrease notably after 10 weeks. And as countries like Germany and South Korea have shortened the wait time for booster shots, US experts are considering a similar approach.

In a briefing released Friday , the UK Health Security Agency announced that the Oxford/AstraZeneca, Pfizer/BioNTech and Moderna vaccines all protect against omicron less than they did against delta and that protection from boosters wanes in time. Booster effectiveness generally decreased to between about 60% and 70% protection at two to four weeks after the shot, down to between about 35% and 45% at 10 weeks, depending on the combination of vaccines administered.

The UK report also adds weight to the hope that omicron infections are less severe than with the delta variant, noting that the risk of hospitalization from omicron is about three-fifths of that from delta.

On ABC’s This Week on Sunday , Dr. Ashish Jha, dean of the Brown University School of Public Health, discussed the possibility of shortening the wait time for boosters. He noted, “The data suggests both from Moderna and Pfizer vaccines that shortening it to as little as three months, but probably more in the sort of four to five months range, because we do see a waning of the immunity of the antibodies by four to five months.”

In a report published Wednesday on the preprint site Medrxiv , scientists at Copenhagen’s Statens Serum Institut examined health records of 3 million Danes taken between Nov. 20 and Dec. 12. They found vaccine effectiveness among seniors 60 and older who had received a booster dose 14 to 44 days earlier averaged 54.6%, according to Reuters . (That’s comparable to the rate found shortly after receiving one shot of the Pfizer vaccine, which quickly wanes.)

Their research hasn’t been peer-reviewed yet, but it follows preliminary data from last week indicating Moderna’s half-dose COVID booster shot can raise antibody levels against omicron 37-fold. Moderna President Stephen Hoge said during a conference call that the lab results were “reassuring” and put booster recipients “comfortably” above the level of a breakthrough risk.

Moderna also indicated a potential double dose of the booster, 100 micrograms versus 50 micrograms, would increase omicron-neutralizing antibodies “approximately 83-fold higher than pre-boost levels.”

Omicron has quickly become the dominant strain in the US , accounting for nearly 75% of new COVID-19 cases. While it appears able to evade some of the defenses offered by two doses of the […]

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