The findings, reported by Moderna on Monday, were the latest positive — though preliminary — results of lab tests suggesting the boosters may protect against the worrying new strain.
The Cambridge, Mass., company said the authorized dose of its booster shot increased levels of immune-system agents known as neutralizing antibodies against Omicron, compared to pre-boost levels by almost 37 times more.
Neutralizing antibodies are among the first troops the immune system deploys to fight off invaders such as the coronavirus.
Paul Burton, Moderna’s chief medical officer, said in an interview, “What we showed is that when you boost, you get a nice sharp increase in antibody levels and they will correlate with protection.”
The authorized booster shot is half the dose level used for each of the first two shots of the vaccine.
Moderna’s findings, along with similar results from laboratory testing by Pfizer Inc. and partner BioNTech SE, suggest that COVID-19 vaccines designed to fight major virus strains during 2020 still hold up well against variants such as Omicron. which are highly mutated.
Yet people must receive a booster shot at the top of the primary series of vaccinations to receive protection.
When Omicron emerged, researchers and health officials expressed concern that the variant could escape vaccines because it has multiple mutations for the spike protein targeted by the shots.
To add to their fears, research shows that Omicron is less sensitive to two doses of Moderna and other COVID-19 vaccines.
Lab-test results released last week by a team of researchers at Moderna, the National Institute of Allergy and Infectious Diseases and Duke University showed that two doses of Moderna’s vaccine significantly reduced neutralizing activity against Omicron. Was.
Pfizer-BioNTech and Moderna’s findings are based on laboratory tests, not clinical trials in volunteers that are considered more definitive.
Moderna disclosed its booster results, which have not been reviewed and published in a news release in a scientific journal. The company plans to share the data with government health officials.
The Omicron variant was identified in late November in southern Africa and has now spread to several countries, including the Americas.
Preliminary studies suggest that it spreads rapidly and re-infects people more easily than other types and that it evades the high amounts of vaccine-induced antibodies. It is not yet known whether Omicron causes more or less severe COVID-19.
The new data may reinforce calls by public-health officials to get booster shots for people who are vaccinated. In the US, only 29.5% of those who are fully vaccinated have received a booster dose, according to the Centers for Disease Control and Prevention.
Moderna also found that using a full dose for the third shot packs a more potent punch than the authorized booster dose. A third full dose increased antibodies against Omicron to approximately 83-fold above pre-boost levels.
Dr. Burton said government regulators may consider recommending a high-dose booster to increase protection in people at high risk of more severe COVID-19.
However, in a separate study, Moderna noted that people receiving high-dose boosters had more adverse reactions than those receiving lower doses.
Dr. Burton said reactions include headache, fever and joint stiffness and must be balanced against the potential benefits of a high-dose booster.
Moderna also tested other experimental booster shots that target older variants, including Delta, and found that they provided a comparable boost to antibody levels against Omicron as its original vaccine booster shot.
Pfizer and BioNTech said a third dose of their COVID-19 vaccine produced neutralizing antibodies compared to just two doses against Omicron.
Given the speed at which Omicron is spreading, Moderna said its near-term priority will be to continue to make booster shots of its original vaccine available.
It said it would continue to work on an Omicron-specific booster shot if needed. Moderna expects to begin clinical trials of an Omicron-specific booster in early 2022.
New data on Moderna’s boosters and Omicron comes from laboratory tests that mix blood samples of vaccinated people with an engineered virus that resembles the Omicron variant. Moderna said the tests were done in the Duke University Medical Center lab, established by the National Institute of Allergy and Infectious Diseases.
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