Immunity to covid-19 decreases, according to a British study

(CNN) – A study of hundreds of thousands of people in England suggests that immunity to COVID-19 is gradually disappearing, at least to one degree.

Researchers who sent fingertip tests home 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 spike in infections in England,” the team wrote. in a pre-printed version of the report, published prior to the peer review.

This is consistent with evidence that immunity to seasonal coronaviruses declines between 6 and 12 months after infection and with emerging data on SARS-CoV-2 which also found a decline in 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.

Immunity to covid-19

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 had them. For healthcare professionals, the rates have remained essentially the same.

Antibodies are the proteins that the body naturally produces to fight infections.

IgG is a type of them and 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 showed that people who had no symptoms of Covid-19 would likely lose detectable antibodies sooner than those who 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 survived an infection.

Antibodies

However, not enough is known to determine whether antibodies provide an effective level of immunity to COVID-19 or how long people may be immune to coronavirus reinfection.

Some infections, such as measles, cause so-called sterilizing immunity.

Infected people never 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 the body’s memory responses to threats like covid-19 will have in providing protection if someone is re-exposed to the novel coronavirus.

More research is needed to better understand the current risks of reinfection.

The study has limitations

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 participate over time and that may have skewed the numbers, the researchers said.

“This large study has shown that the proportion of people with detectable antibodies is decreasing over time,” Helen Ward, who is a member of the medical school at Imperial College London School of Public Health, said 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 follows the guidelines to reduce the risk for themselves and others,” added Ward, who. worked in the studio.

Previous national prevalence surveys that determined how many people had COVID-19 in Iceland recorded a lasting antibody response for four months from the time of infection.

Other studies have shown that several factors can affect the rate at which antibodies decline. Age, comorbidities, and initial disease severity appear to play a role.

An advance

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 appropriate action to control the spread of Covid-19.

“It’s also important for everyone to know what this 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 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 as far as antibodies are concerned, this coronavirus behaves like other coronaviruses.

As with a cold, the antibodies are lowered and people can catch a cold more than once.

Also, just like with a cold, people with robust immune systems, usually young people, generally don’t see a drop in antibodies as rapidly as people with older immune systems.

“Piece of the puzzle”

“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 insane.”

Hoyen said the study “also confirms the fact that we will be wearing masks for a while.”

“I know we all hope this ends soon, but I don’t think it will,” he said.

“I think first we will be convinced that this is what we need to do to overcome it, we can accept it and move on. These data clearly show that their antibodies disappear. So just because you’ve had it once doesn’t make you immune and also means you can get it again.