Most Covid vaccines act as boosters, studies suggest

If you’re looking for a booster shot of the Covid-19 vaccine, you probably don’t have to worry about which brand it is. Many combinations of shots can provide strong protection, according to a large new study.

In a comparison of seven different vaccine brands, British researchers found that most of them stimulated a strong immune response, with mRNA shots from Moderna and Pfizer-BioNTech eliciting the greatest response.The research is Published on Thursday With a lancet.

“These are welcome data for policy makers,” said Mary Boise, a statistician at Oxford University who was not involved in the study. “The most important takeaway message here is that there are many excellent boost options for the third dose.”

It’s too early for researchers to talk a lot about how well different vaccine boosters work for new ones. Omicron Mutant. There are mutations that may avoid some of the antibodies produced by existing Covid-19 vaccines. Some researchers suspect that people will need very high levels of antibodies to protect against it.

All 2,878 volunteers in this study were initially vaccinated twice with AstraZeneca or Pfizer. (Both of these vaccines are licensed in the United Kingdom. Shots by Pfizer, Modana, Johnson & Johnson are licensed in the United States.)

Next, the researchers tested seven different vaccines as boosters. With AstraZeneca and Pfizer, I tried three brands licensed in different countries. Johnson & Johnson, modern When Novavax..They also tried two shots that are not licensed anywhere: the mRNA vaccine from Cureback, And a vaccine from Valneva made from Inactivated coronavirus.. Finally, some of the volunteers were vaccinated with meningitis vaccine as a control.

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

Those who received the Covid-19 booster shot had increased antibody and T cell levels compared to those who received the meningococcal vaccine. However, the range was quite wide. The number of people who received the Valneva booster after the Pfizer vaccine was only 30 percent higher than the control group. However, the Moderna booster has resulted in an increase of at least 1,000 percent.

New research has also found that boosters increase the number of T cells that recognize coronavirus. Antibodies may be excellent at knocking out coronavirus early in the infection when the virus is colonizing the nose. However, deep in the airways, T cells can provide a second line of defense.

This trial did not follow volunteers to see how much booster shots actually prevented infections and illnesses.But in recent months, researchers have shown that measuring antibody levels can be a pretty good way to go. predict Vaccine efficacy.

Most of the boosters used in this study raised antibodies to levels equivalent to at least 90 percent protection against infection. And the mRNA vaccine by Pfizer and Moderna produced much higher antibody levels than other vaccines.

Eleanor Riley, an immunoscientist at the University of Edinburgh who was not involved in the new study, said:

Still, other scientists said most of the other vaccines in the study worked powerful enough that people should feel comfortable getting them.

Saul Faust, a university infectious disease expert, said: Co-author of research with the University of Southampton. “It’s not all about mRNA.”

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

“I don’t consider it a beauty pageant, in a way it’s slightly higher than other contests,” he said. “I can’t afford to do anything too valuable about this.”

Dr. Moore said the new study can give public health authorities the confidence to look at different vaccines for booster immunity, depending on what is most convenient. For example, Novavax and Johnson & Johnson make vaccines that can be stored in the refrigerator, but mRNA vaccines need to be cryopreserved.

An inevitable drawback of the new study was that researchers did not measure boosters for the new Omicron variant. Omicron, just discovered last month, has raised serious concerns among researchers due to its many mutations. Boosters that are 90% effective against the original strain can be exacerbated against Omicron.

I don’t know how bad it is. Omicron’s experiments have not begun, as scientists first need to understand how to grow mutants in the laboratory. Dr. Faust and his colleagues have already sent blood samples from test volunteers to a UK government laboratory. There, researchers will see how well boosted antibodies and immune cells work against Omicron. “I think we’ll start seeing those results within a few weeks,” said Dr. Faust.

If the booster does not work well for the variant, vaccine developers will need to create new shots, said Dr. Stanley Plotkin, a vaccine expert and professor emeritus at the University of Pennsylvania. mRNA vaccines can be rapidly adapted to target mutations in Omicron, or researchers can try a more challenging approach: universal vaccines. Against coronavirus..

“Assuming that Omicron escapes antibodies against the original virus and the current variant, we must have a different philosophy,” he said.