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(CNN) – A study of hundreds of thousands of people across England suggests that coronavirus immunity is gradually waning, at least to one degree.
Researchers who sent home finger-prick tests to over 365,000 randomly selected people in England found a drop of more than 26% in Covid-19 antibodies in just three months.
“We observe a significant drop in the proportion of the population with detectable antibodies in three rounds of national surveillance, using a self-administered lateral flow test, 12, 18 and 24 weeks after the first spike in infections in England,” the team wrote in a pre-printed version of their report, issued prior to the peer review.
“This is consistent with evidence that immunity to seasonal coronaviruses decreases 6 to 12 months after infection and with emerging data on SARS-CoV-2 which also found decreased antibody levels over time in followed individuals. in longitudinal studies “,
The study was published Monday by Imperial College London and Ipsos MORI, a market research firm. At the start of the study in June, 6 percent of those who took the tests had IgG antibody responses to the coronavirus, they reported. In September, only 4.4% of them did. For healthcare professionals, the rates have remained more or less the same.
Antibodies are the proteins your body naturally generates to fight infections. IgG is one type: the tests were not designed to detect other types of antibodies. Other research groups have found that other types of antibodies can persist longer than IgG.
The findings also confirm previous studies that have shown that people who had no symptoms of Covid-19 are at risk of losing detectable antibodies earlier than those who have had more severe infections.
The researchers found that younger people who recovered from Covid-19 had slower antibody loss, compared to people over the age of 75 who had survived an infection.
However, not enough is known to determine whether the antibodies provide an effective level of immunity to Covid-19 or how long people can be immune to reinfection with the coronavirus.
Some infections, such as measles, cause so-called sterilizing immunity. Once infected people have antibodies that can be detected for many years after infection.
With coronaviruses, scientists know less. It is also unclear what contribution T-cell immunity and body memory responses to threats like Covid-19 will play in providing protection if someone is exposed to the novel coronavirus again. More research is needed to better understand the risks of reinfection.
The study has limitations. The samples were not taken repeatedly by the same people, but by different people over time. It is possible that people who had been exposed to the coronavirus were less likely to take part in it over time and this may have skewed the numbers, the researchers said.
“This very large study showed that the proportion of people with detectable antibodies is decreasing over time,” said Helen Ward, who is in medical school at Imperial College London’s School of Public Health, in a statement.
“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 continues to follow directions to reduce the risk for themselves and others,” added Ward, who. worked at the studio.
The first national prevalence surveys that determined how many people had Covid19 in Iceland recorded a durable antibody response for four months from the time of infection. Other studies have shown that several factors can affect how quickly antibodies drop. Age, comorbidities, and initial disease severity all seem to play a role.
UK Health Minister Lord James Bethell called the study a “key piece of research” that could help inform the UK government on how to take the right action to control the spread of Covid-19.
“It’s also important that everyone knows what it means to them – this study will help in our fight against the virus, but being positive for antibodies doesn’t mean you’re immune to Covid-19,” Bethell said in a news release. “Regardless of the result of an antibody test, everyone must 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, thought the study was interesting and encouraging, as it suggests that at least when it comes to antibodies, this coronavirus behaves like other coronaviruses. As with a cold, the antibodies drop and people can get colds more than once. Also, as with a cold, people with robust immune systems, typically young people, typically don’t see a drop in antibodies as rapidly as with people with older immune systems.
“This study is really like the first piece of the puzzle that actually gives us an indication that, yes, these antibodies don’t seem to hang around for everyone,” Hoyen said. “At least in this case, this virus behaves as we can predict, which is good because everything about this virus has been so out of the ordinary.” Hoyen said the study “also reinforces the fact that we’ll be in masks for a while.”
“I know we all hope this will end soon, but I don’t think it will happen,” he said.
“I think first we settle down to the fact that this is what we need to do to get over this, we can accept it and move on. This data clearly shows that your antibodies disappear. So just because you had it once, it doesn’t make you immune. and it also means you can be contagious again. “
This story was first published on CNN.com, “A British Study Shows Evidence of Decreased Immunity to Covid-19”
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