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People looking for a booster shot of a Covid-19 vaccine probably don’t need to worry about which brand it is: Many combinations of vaccines are likely to offer strong protection, according to a major new study.

In comparing seven different vaccine brands, British researchers found that most of them elicit a strong immune response, and the mRNA shots from Moderna and Pfizer-BioNTech elicited the greatest responses. study Published on Thursday at The Lancet.

“These are welcome data for policymakers,” said Merryn Voysey, a statistician at Oxford University who was not involved in the study. “The most important take-home message here is that there are many excellent enhancement options for third doses.”

It’s too soon for researchers to say much about how well different vaccine boosters will work against new vaccines. Omicron Variant with mutations that could allow it to evade some antibodies produced by current Covid-19 vaccines. Some researchers suspect that people would need very high levels of antibodies to protect against it.

All of the study’s 2,878 volunteers received two shots of either AstraZeneca or Pfizer vaccines at baseline. (Both of these vaccines are approved in the UK; vaccines by Pfizer, Moderna, and Johnson & Johnson are approved in the United States.)

The researchers then tested seven different booster vaccines: AstraZeneca and Pfizer, as well as three brands authorized in various countries: Johnson and Johnson, modern and Novavax. They also tried two vaccines that were not allowed anywhere: an mRNA vaccine. CureVacand a vaccine made from Valneva inactivated coronaviruses. Finally, some of the volunteers received the meningitis vaccine as a control.

Four weeks later, the researchers collected blood samples from the volunteers and measured their antibody levels. They also looked for immune cells known as T cells that specifically attack other cells infected with the coronavirus.

Antibodies and T-cell levels were increased in people who received the Covid-19 booster vaccine compared to those who received the meningitis vaccine. But the range was quite wide. People who took the Valneva booster after a Pfizer vaccine saw only a 30 percent increase over the control group. But a Moderna booster gave at least a 1000 percent boost.

The new study also found that boosters increase T cells that recognize the coronavirus. Antibodies may be good at knocking out a coronavirus early in an infection while the virus colonizes the nose. But T cells deep in the airway can provide a second line of defense.

The trial did not follow the volunteers to see how well the booster shots actually prevented infection or disease. But in recent months, researchers have shown that it can be a pretty good way to measure antibody levels. prediction efficacy of a vaccine.

Most of the boosters used in the study raised antibodies to a level equivalent to at least 90 percent protection against infection. And Pfizer and Moderna’s mRNA vaccines produced much higher levels of antibodies than other vaccines.

“I’d say it’s probably a good idea to have an mRNA enhancer whatever you’re experiencing for the first time,” said Eleanor Riley, an immunologist at the University of Edinburgh, who was not involved in the new study.

Still, other scientists said most of the other vaccines in the study performed strong enough that people felt comfortable receiving them.

“If there’s only one of the vaccines we’ve shown you can accelerate in your country or in your region of the world, it would be fine to use it as a vaccine, and it would be safe to do so,” said Saul Faust, an infectious disease specialist at the university. He is from Southampton and co-author of the study. “It’s not all about mRNA.”

John Moore, a virologist at Weill Cornell Medicine in New York who was not involved in the study, said people shouldn’t be making too much of the modest differences between most vaccines.

“I don’t see it as a beauty pageant in the sense that one is slightly higher than the other,” she said. “We can’t afford to be too valuable on this one.”

Dr. Moore said the new study could give public health officials the confidence to turn to different vaccines for boosters, depending on which one is most appropriate. For example, Novavax and Johnson & Johnson produce vaccines that can be stored in refrigerators, while mRNA vaccines must be stored frozen.

An inevitable shortcoming of the new study was that the researchers did not measure the enhancers against the new Omicron variant. Discovered just last month, Omicron has caused serious concern among researchers because of its many mutations. A booster that’s 90 percent effective against the original type may do worse against Omicron.

How much worse is unknown. Experiments on the Omicron have not started because scientists first need to figure out how to grow the variant in the lab. Dr. Faust and his colleagues have already sent blood samples from trial volunteers to British government laboratories, where researchers will see how well their boosted antibodies and immune cells work against Omicron. Dr. “I think we’ll start seeing these results in a few weeks,” Faust said.

A vaccine expert and University of Pennsylvania professor emeritus, Dr. If the boosters don’t work well against the variant, vaccine developers will need to give new shots, Stanley Plotkin said. He added that mRNA vaccines could be rapidly adapted to target mutations of Omicron, or that researchers could try a more challenging approach: a universal vaccine. against any coronavirus.

“Assuming that Omicron evades antibodies against the original virus and existing variants, then we must have a different philosophy,” he said.