Why you shouldn’t worry about studies showing the decline of coronavirus antibodies

The proportion of people in the UK who can detect antibodies to the coronavirus has decreased by about 27% over the three months of this summer. Researchers reported on Monday, Promotes the fear that immunity to the virus is short-lived.

However, some experts said these concerns were exaggerated. Although it is normal for the body to reduce antibody levels after it has cleared the infection, immune cells can carry the memory of the virus and mass-produce fresh antibodies as needed.

“Some of these headlines are ridiculous,” said Scott Hensley, an immunologist at the University of Pennsylvania.

Decreased antibody levels after the acute infection has resolved are “a sign of a normal, healthy immune response,” said Dr. Hensley. “It doesn’t mean that those people no longer have antibodies. It doesn’t mean they aren’t protected.”

The study also raised some concerns about the ability of vaccines to help populations reach herd immunity. This is the point at which enough people immunize the coronavirus to stop the spread of the coronavirus.

It is premature to know how long the immunity to the new coronavirus will last and whether people can re-infect months to a year after the first attack of the virus. Still, experts said that concerns about vaccines were also unjustified.

“Vaccines do not have to mimic or reflect natural infections,” said Shane Crotty, a virologist at the Lahora Institute for Immunology. “Sure, I’m not wary of these data.”

The new results show the prevalence of coronavirus antibodies in a wider population rather than in a specific individual.Some studies examining individual antibody levels show that after some initial decline, levels are Be firm at least four To seven Month.

The UK report is based on a three-round antibody blood test performed on 350,000 randomly selected individuals from June 20th to September 28th. It’s like a pregnancy test.

Researchers reported that over the course of three months, the proportion of people with detectable antibodies in their blood dropped from 6% to 4.8%. The smallest decrease was in people aged 18-24, and the largest decrease was in people aged 75 and over.

Looking at the data in another way, about 73% of people who had antibodies early had positive results months later, said Antonio Bertoletti, a virologist at Duke NUS Medical College in Singapore. Dr. Bertoletti said. “It’s not a dramatic decline.”

Antibodies, which are also the easiest to measure, are just one arm of the immune response. Antibody levels do not give a complete picture, as there are at least three other branches of the immune system that can dodge the disease.

“It’s not a complete immune response,” said Dr. Paul Elliott, an epidemiologist at Imperial College London, who leads the project.

When the body encounters a pathogen, it quickly produces antibodies that recognize intruders. Once the acute infection is resolved, the level drops — for purely practical reasons.

“Our lymphatic system, where immune cells are present, has a limited amount of space,” said Dr. Hensley.

Depending on the test used, a small amount of antibody circulating in the blood may not be enough to give a positive signal. The test sensitivity used in this study was 84.4%, well below the sensitivity of lab-based tests. About 99% hovering.. In other words, you may miss people with low antibody levels.

For example, people with mild to no symptoms may produce less antibodies than people with severe illness. Most people with positive results were ill in March or April, the peak outbreak in the UK, but about 30% did not remember the symptoms of Covid-19. Even a slight decrease in the amount of antibody can result in antibody levels below the detection limit.

“We say the antibody response is below the threshold,” Dr. Elliott said. “This is not a surprise to those who work in the field.”

Monkey data suggest that low levels of antibodies, even if not reinfecting, can prevent serious viral illness. The body retains pathogen memory even when circulating antibody levels cannot be detected. If it crosses the virus and pathways again, the balloon-like cells that live in the bone marrow can mass-produce antibodies within hours.

Very few people may not make antibodies. However, even those people may have immune cells called T cells that can identify and destroy the virus.It affects the majority of people infected with the coronavirus Sustained cellular response, According to some recent research.

Although T cells are unlikely to prevent infection, blunting the attack can at least prevent serious illness, Dr. Crotty said. With that all in mind, he said, it was “wrong” to interpret low antibody levels as meaning immunity loss or ineffective coronavirus vaccines.

For example, the human papillomavirus “induces a terrible immune response and terrible antibodies,” he said. “But vaccination with a single vaccination gives us a great antibody that protects people 99% for over a decade. This is the perfect difference between day and night.”

Vaccines can also be designed to provoke a much stronger response than natural infections, he added.

While criticizing many of its interpretations, experts said the results of the new study are an interesting glimpse into the prevalence of antibodies at the population level.

The same research team is also testing hundreds of thousands of people for the presence of the virus. Together, Dr. Elliott said the study would provide policy makers with a “really powerful tool” to measure the magnitude of a country’s epidemic.