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Researchers who sent home fingerstick tests to more than 365,000 randomly selected people in England found a decrease of more than 26% in Covid-19 antibodies in just three months.
“We observed a significant decrease in the proportion of the population with detectable antibodies during three rounds of national surveillance, using a self-administered lateral flow test, 12, 18 and 24 weeks after the first peak of infections in England,” the team wrote. in a pre-printed version of your report, published before peer review.
“This is consistent with the evidence that immunity to seasonal coronaviruses declines between 6 and 12 months after infection and emerging data on SARS-CoV-2 that also detected a decrease over time in antibody levels in individuals followed in longitudinal studies “.
The study was published Monday by Imperial College London and Ipsos MORI, a market research company. At the beginning of the study, in June, 6% of those who were tested had IgG antibody responses to the coronavirus, they reported. In September, only 4.4% of them did. For health workers, the rates remained largely the same.
The results also confirm previous studies that showed that people who did not have Covid-19 symptoms would likely lose detectable antibodies earlier than those who had more serious infections.
Younger people who had recovered from Covid-19 had a slower loss of antibodies, compared to people older than 75 who had survived an infection, the researchers found.
Some infections, such as measles, cause what is known as sterilizing immunity. Infected people ever have antibodies that can be detected for many years after infection.
The study has limits. The samples were not taken from the same people over and over, but from different people over time. It’s possible that people who had been exposed to the coronavirus were less likely to participate over time, and that may have skewed the numbers, the researchers said.
“We do not yet know if this will leave these people at risk of reinfection with the virus that causes COVID-19, but it is essential that everyone follows the guidelines to reduce the risk to themselves and others,” added Ward, who worked on the study.
The UK Health Minister Lord James Bethell called the study a “critical piece of research” that could help inform the British government on how to take appropriate measures to control the spread of Covid-19.
“It is also important that everyone knows what this means to them: this study will help in our fight against the virus, but testing positive for antibodies does not mean that you are immune to Covid-19,” Bethell said in a press release. “Regardless of the result of an antibody test, everyone should continue to adhere to government guidelines, including social distancing, self-isolation, and getting tested if you have symptoms and always remember Hands, Face, Space.”
Dr. Claudia Hoyen, who specializes in pediatric infectious diseases at Cleveland University Hospitals, found the study interesting and encouraging as it suggests that at least when it comes to antibodies, this coronavirus acts like other coronaviruses. As with a cold, antibodies decrease, and people can catch a cold more than once. Also, just like with a cold, people with robust immune systems, typically younger people, typically don’t see as rapid a drop in antibodies as people with older immune systems.
“This study is really like the first piece of the puzzle that really gives us the indication that, yeah, these antibodies don’t seem to stick around for everyone,” Hoyen said. “At least in this case, this virus is acting as we can predict, which is a good thing because everything about this virus has been so crazy.” Hoyen said the study also “solidifies the fact that we will be in masks for a while.”
“I know we all hope this will end soon, but I don’t think it will,” he said.
“I think the sooner he solves for us the fact that this is what we have to do to get through this, we can accept it and move on. This data clearly shows that his antibodies go away. So just because he’s had it once, it doesn’t immune and it also means you can catch it again. “
