Dubai, United Arab Emirates (CNN) – In 2010, doctors told Bin Subic, who is now 37, that he was suffering from kidney failure of unknown cause. Soon, Sobek underwent a kidney transplant and started taking immunosuppressive drugs that weaken his immune system, to make sure his body doesn’t reject the donor organ. Doctors never found out why his kidneys were failing. But a decade later, Subic faced another threat to his health, the COVID-19 pandemic.
“I take immunosuppressive drugs that make me more susceptible to serious Covid complications,” said Sobek, who lives in the US state of Minnesota, adding: “If you are immunocompromised, you may not have a very good response to the Covid-19 vaccine.”
Sobek looked for clues to whether his immune system was working properly and asked his doctor, a nephrologist, an unfamiliar question for a blood test that would give him a rough measure of his antibody level, a type of protein the body produces in response to an injury or vaccine. The test detects specific antibody concentrations in the blood.
Millions of Americans, and not only those with weakened immune systems, wonder about their immunity after receiving boosters during the winter and infection with the “Omicron” mutation. After giving up the protective mask, and removing restrictions in implementation of the trend to return to normal life, an immunoassay will be a powerful tool for determining an individual’s risk.
“The main reason to check my antibody measurements is because I don’t know how to assess the risks I might face,” Sobek said. He added, “Anyone who has been immunocompromised since the beginning of the pandemic until today has few tools to assess risk, to know if they can leave the house, when to leave, or how to mix with other people, and when is the best.”
Sobek’s antibody levels were checked after the second, third and fourth doses of Moderna vaccine. Each result showed he had more antibiotics than the test could detect, suggesting he had a strong immune response.
Although there were no specific guidelines for interpreting these results in order to know the level of protection from injury or disease, Sobek felt reassured that his immune system was doing its job.
“More than 50% of transplant patients do not have an adequate immune response to protect them, even if they receive three, not just two, doses of vaccines intended for the general public,” said Dr. Dore Segev, professor of surgery at the New York University Langone School of Health. “For them, the antibody measurement is irrefutable evidence that they have some form of immunity.”
Segev supports the use of tests to measure antibodies as a way to ensure immune protection in immunocompromised individuals.
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By December, about 95 percent of Americans 16 and older had COVID-19 antibodies, the most recent date for available data, according to the U.S. Centers for Disease Control and Control, which was based on estimates using information from donors. by blood.
This is a way to measure antibody levels. But is there a way to measure the protection offered by these levels of “Covid-19”?
The US Food and Drug Administration never recommends checking antibody levels because there is no agreed upon way to calculate how antibody levels can protect you from infection or severe illness. It can also reflect a false sense of security.
“There are no good links to protection – anything that says that’s the measurement one needs to know how protected they are,” said Mehul Suthar, a virologist at Emory University in the US.
Scientists are trying to bridge this knowledge gap. Studies measure the average antibody levels of a group of people to verify the effectiveness of the vaccine, and are often based on antibody levels months after receiving the vaccine in order to determine the need for a booster dose.
One study of people who received the Moderna vaccine showed that higher antibody levels after vaccination were associated with a lower risk of infection with Covid-19.
But not all antibodies are formed the same way. A small part of the antibodies that the body makes after infection or vaccination are considered neutralizing antibodies, that is, they can effectively fight infection.
Antibody tests are also divided into quantitative and qualitative. Quantitative tests include a specific number of antibodies in the blood, which you do not exceed. Specific tests determine if only certain antibodies are detected. The results of qualitative tests are either positive, negative or nonspecific for neutralizing antibodies.
And when it comes to measuring neutralizing antibodies specifically, one type of test that has received emergency use authorization from the Food and Drug Administration for its detection is a qualitative test.
Numerous studies have shown that neutralizing antibodies form strong protective bonds that protect against infection accompanied by symptoms of “Covid-19” and its variants, with enhanced doses strengthening their neutralization.
Peter Gilbert, professor of vaccines and infectious diseases at the Fred Hutchinson Cancer Research Center and lead author of the Moderna study, said these links are useful to apply to large groups, as scientists use data from larger studies centered on the relationship between antibody levels and vaccine efficacy in adults to predict Vaccine efficacy in children.
However, drawing conclusions based on a single person’s antibody levels is very limited.
This is due to how antibody levels vary from person to person. This association with protection also changes over time and with different coronavirus variants, making it difficult to put a limit on antibody levels at which scientists can confidently tell that someone is protected from COVID-19.
Natural versus acquired immunity from a vaccine
There is a key difference in how the levels of antibodies caused by receiving the “Covid-19” vaccine compare with those who have had the Corona virus.
Suthar said, “The immune response to the vaccine may be high in those who have been immunized and have high antibodies that will fade somewhat over time… But the outcome is different in the case of infection, as many patients will have a low or high level of antibody responses.”
The US Centers for Disease Control and Prevention cited a published study, which has not been peer-reviewed, that showed that the number of antibodies diminished more rapidly in those who received the vaccine than in infected people. This may help explain the growing evidence that a stronger, more permanent vaccine is effective in people who have acquired immunity through disease and vaccination, known as hybrid immunity.
Although they may not provide the best way to know how well someone is protected, antibodies are useful for understanding how people who have natural immunity compare to those who have gained immunity from a vaccine.
“We know that people with this hybrid immunity have better protection,” said Marion Pepper, an assistant professor of immunology at the University of Washington, who leads a laboratory that studies hybrid immunity. So this raises the question: Which of these criteria is associated with this protection?
Monitoring levels of immune cells and antibodies as they change over time in different groups of people can help scientists learn how to make vaccines and when to vaccinate so that the hybrid immune force can reproduce without actually getting infected.