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Long-awaited new research highlights antibodies scientists can test to see if a COVID-19 vaccine is working. These “correlates of protection” could accelerate the development of new vaccines or boosters without requiring the massive clinical trials used to create the first COVID-19 vaccines.
Instead, researchers could vaccinate people with a new vaccine or a new booster, measure their antibodies over several months, and find out if it was working.
This is “the holy grail” in terms of vaccines, and has yet to be defined for the virus that causes COVID-19, said Peter Gilbert, co-author of the study published Tuesday on medRxiv, a Preprint site where scientific papers can be published before being accepted by peer-reviewed journals.
“The hope is that the Food and Drug Administration will see this data and use it as a mechanism for interim approval,” he said.
Gilbert is a biostatistician at the Fred Hutchinson Cancer Research Center in Seattle, which also heads the statistical center of the federal government’s COVID-19 Prevention Network.
Although the study did not undergo the strict peer review required by standard scientific journals, such preprints became common during the COVID-19 pandemic. Gilbert and his co-authors are highly esteemed researchers who have previously published on the subject of correlates of protection and submitted the article to a standard review.
“This is a well-done and important collaborative job,” said Dr Jesse Goodman, professor of medicine and infectious diseases at Georgetown University, who was not affiliated with the research.
Such correlates have long been used to help create vaccines against other diseases, such as influenza.
“Such measures should help speed up the evaluation, including by regulators, of vaccines used in new populations and / or made with variants.”
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Measuring “soldiers on the ground”
Researchers in the Coronavirus Efficacy (COVE) study measured the levels of two antibody markers in the blood of study participants to see if they correlated with the risk of COVID-19.
The study ran from July to October 2020 and included 30,415 participants. Half received two doses of the Moderna vaccine, half received a placebo. Of these, 1,051 vaccine recipients had their antibodies measured.
Two types of markers were measured: neutralizing antibodies and binding antibodies. Both types have been used as correlates for the protection of vaccines against other viral diseases.
Neutralization markers measure the strength with which antibodies prevent the virus from infecting cells. Binding antibody markers measure the number of antibodies that bind to the spike protein.
“You could say it measures the number of soldiers who see the virus and go to the battlefield,” Gilbert said.
Participants’ blood was tested twice for marker levels, once after their second injection of Moderna’s COVID-19 vaccine and again four weeks later.
The more antibodies participants have, the lower their chances of contracting COVID-19. This was true for all antibody markers at both time points.
The effect lasted for up to four months after the second dose of the vaccine. It may take longer, but the study is still ongoing. Future research will examine whether lower antibody levels correspond to more severe cases of COVID-19 and whether there is a correlation between age or health problems.
It’s important to remember that the antibody levels measured may not represent everything that protects people from the virus, Goodman said.
“Antibody levels may decrease, but other aspects of the immune system not mentioned in this study, such as T cells and memory B cells, can potentially help provide substantial protection against disease, and in particular against serious consequences, ”he said.
For this reason, it is still not possible to say that declining antibodies are truly predictors of risk. Studies evaluating actual clinical protection and its correlation with antibody levels are still needed, he said.
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Strong link between antibodies, protection
Similar data was recently published by the University of Oxford in England on the AstraZeneca vaccine and in Israel on the Pfizer vaccine. In both studies, higher antibody levels corresponded to lower disease rates.
Although they used different tests to measure the levels, they are evidence of a strong link between antibodies and protection.
The antibody levels the researchers looked at don’t mean individuals can go out and have their blood drawn to see if they’ve developed an effective antibody response against the virus, Gilbert said.
“I don’t think anybody’s talking about individuals who walk into a clinic, find out their antibodies are low and get revaccinated. That’s not really the point of this research,” he said. “This is to provide a way to quickly approve new vaccines.”
One of the tests used by researchers is not readily available in the average medical lab, said Alan Wu, professor of laboratory medicine at the University of California at San Francisco and head of the clinical chemistry and toxicology labs. of the Zuckerberg San Francisco General. Hospital.
The test also doesn’t measure everything that is going on in a person’s immune system.
“How do you interpret the results, because neutralizing antibodies are only half the picture?” We also have immunity to T cells, ”Wu said.
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This article originally appeared on USA TODAY: Antibody Levels Could Predict COVID Vaccine Efficacy: Research
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