In lab tests, a third dose of Moderna Inc.’s Covid-19 vaccine increased immune responses against the Omicron coronavirus variant compared to two doses, indicating that the shot may still offer protection despite the variant’s mutations.

The findings, reported on Monday by Moderna, were the latest positive—though preliminary—results from lab tests indicating boosters can protect against the concerning new strain.

According to the Cambridge, Massachusetts-based company, the approved dosage of its booster shot increased levels of immune-system agents known as neutralizing antibodies against Omicron 37 times higher than pre-boost levels.

Neutralizing antibodies are among the first soldiers deployed by the immune system to combat invaders such as the coronavirus.

“What we demonstrated is that when you boost, you get a good brisk increase in antibody levels, and they are correlated with protection,” Moderna Chief Medical Officer Paul Burton explained in an interview. The authorized booster shot is half the dose level used for the vaccine’s first two shots.

Together with similar findings from Pfizer Inc. and partner BioNTech SE, Moderna’s findings suggest that Covid-19 vaccines designed to combat the virus strain that was prevalent in 2020 may still hold up well against significantly mutated variants such as Omicron.

However, in order to gain protection, people would need to receive a booster shot in addition to the primary series of vaccinations.

When Omicron was discovered, scientists and health officials expressed concern that the variant could evade vaccines due to numerous mutations in the spike protein targeted by the shots.

Research indicating that Omicron is less susceptible to two doses of Moderna’s and other Covid-19 vaccines added to their concerns. A team of researchers from Moderna, the National Institute of Allergy and Infectious Diseases, and Duke University published lab results last week showing that two doses of Moderna’s vaccine had significantly reduced neutralization activity against Omicron.

The findings from Pfizer-BioNTech and Moderna are based on lab tests rather than the more definitive clinical trials in volunteers.

In a news release, Moderna disclosed its booster results, which had not been peer reviewed or published in a scientific journal. The data will be shared with government health officials, according to the company.

The Omicron variant was discovered in southern Africa in late November and has since spread to many countries, including the United States.

According to preliminary research, it spreads faster and re-infects people more easily than other variants, and it evades vaccine-induced antibodies to a greater extent. It is unknown whether Omicron causes more or less severe symptoms. Covid-19. The new data may support public-health officials’ calls for vaccinated people to get booster shots. According to the Centers for Disease Control and Prevention, only about 29.5 percent of fully vaccinated people in the United States have received booster doses.

Moderna also discovered that using the full dose for the third shot delivered a stronger punch than the authorized booster dose. A third full dose increased neutralizing antibodies against Omicron by approximately 83 times over pre-boost levels.

Dr. Burton believes that government regulators should consider recommending higher-dose boosters to increase protection, at least among people who are at higher risk of more severe Covid-19.

In a separate study, Moderna found that people who received the higher-dose booster experienced more adverse reactions than those who received the lower dose.

According to Dr. Burton, the side effects include headache, fever, and joint stiffness, which should be weighed against the potential benefits of a higher dose booster. Moderna also tested other experimental booster shots that target older variants, such as Delta, and discovered that they provided a comparable boost to antibody levels against Omicron as the original vaccine booster shot.

According to Pfizer and BioNTech, a third dose of their Covid-19 vaccine increased neutralizing antibodies against Omicron when compared to just two doses.

Given the rapid spread of Omicron, Moderna stated that its immediate priority will be to continue providing booster shots of its original vaccine.

It stated that it would continue to work on an Omicron-specific booster shot in case it is required. Moderna anticipates that clinical trials of an Omicron-specific booster will begin in early 2022.

The new information on Moderna’s booster and Omicron came from laboratory tests that combined blood samples from vaccinated people with an engineered virus that resembled the Omicron variant. The tests were conducted at Duke University Medical Center labs that were established by the National Institute of Allergy and Infectious Diseases, Moderna said.