New evidence points to antibodies as a reliable indicator of vaccine protection
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Dr. Anthony Fauci recently spoke at a White House briefing on the need for COVID-19 boost shots. In his slideshow of data points and charts was an obscure scientific paper that provides evidence for a reliable method to predict the level of protection a COVID-19 vaccination offers.
Although the study was not widely publicized, it appeared on a preprint server early this month. Many people who are interested in COVID-19 vaccines' future have eagerly awaited the results.
Researchers were searching for markers in the blood of vaccinated patients that could indicate protection against COVID-19 (also known as "correlates of immunity"). The scientists discovered neutralizing antibodies proteins, which are immune system proteins that can disarm coronavirus.
Fauci explained that the paper demonstrated that vaccine efficacy is associated with higher levels. These findings indicate that people could be protected against the coronavirus by receiving a booster vaccine which has been shown in the ability to increase antibody levels.
Although more research is needed to confirm these findings, the discovery that these markers correlate positively with immune protection has important implications for future COVID-19 vaccine research. Researchers can now determine whether a new COVID-19 vaccination might be effective without having to repeat large-scale efficacy trials.
Peter Gilbert, a biostatistician at the Fred Hutchinson Cancer Research Center and the lead author of the study, said that "that could be used as a basis for authorization and approval vaccine candidates without having to do these trials in 40,000 people that take an expensive and long time to complete."
Why are we looking for immune correlates
A team of researchers from industry, academia, and government conducted new research to determine if there was a protective level for neutralizing antibodies. This older trial with 30,000 volunteers was the basis of the Food and Drug Administration's emergency authorization for Moderna's COVID-19 vaccine.
The Moderna study found 46 people who were vaccinated but then became sick from COVID. This was compared with levels in 1,000 people who were vaccinated in the trial, and they never became sick.
Gilbert states that the antibody levels of people who were vaccinated became COVID cases were lower than those who were not vaccinated.
These results showed that antibodies can predict immunity. This should allow for faster development and testing of new vaccines. COVID-19 vaccine manufacturers may not have to run large-scale trials on large numbers of people in order to determine how many become ill after being vaccinated. Researchers could instead draw blood to determine if there are antibodies that correlate with protection.
Gilbert suggests that a vaccine might only be effective if it was tested on a few hundred people rather than tens to thousands.
There is no magic number yet
The paper identifies four indicators of immunity that should be used to indicate the effectiveness of a COVID vaccine overall. However, the blood test can't tell if a person is protected.
It would be wonderful if the antibody level were a precise number but it is not, according to David Benkeser, Emory University biostatistician and another author of the study.
He says, "Unfortunately the story is a bit less subtle than that." We see this more as a continuum. Some antibodies [are] good. More is better.
It is clear, however, that antibodies are not enough to explain why certain people are protected. Other parts of the immune system play an important role in fighting the coronavirus including T-cells.
Christopher Houchens (a biomedical researcher at Biomedical Advanced Research & Development Authority) said that two percent of those who had been vaccinated had low levels of antibodies. He was also the author of the study. "However, approximately 50 percent of those in the two percent were still protected and didn't get symptomatic COVID-19."
Federal regulators need to be convinced of the importance of more research
To determine if the same pattern exists, researchers plan to conduct a similar analysis on the relationship between vaccine-induced immunity and antibodies in those who took part in the Johnson & Johnson COVID-vaccine trials.
It is also planned to collect data on what are known as challenge studies. This involves deliberately infecting people with the coronavirus to test how well the vaccine protects them against infection.
Multiple studies are needed to convince federal regulators that antibodies alone can provide sufficient evidence for approval and authorization of future COVID vaccines.
This is not surprising.
Holly Janes, a biostatistician from the Fred Hutchinson Cancer Research Center, who designed the antibody study, says that science is complex. It's not neat and tidy. It's important to look at things in different ways and in different types and types of studies. There is rarely one study that can tell us all we need to know.
