Immunity to Covid-19 against antibodies may last only a few months, UK study suggests

07/14/2020 Health, Science, World


The document, published on the medrxiv.org medical server on Saturday and not yet published in a peer-reviewed medical journal, suggests that antibody responses may begin to decline 20 to 30 days after symptoms of Covid-19 arise. . Antibodies are proteins that the body produces to fight infection.

“We showed that IgM and IgA binding responses decrease after 20-30 days,” wrote researchers from UK institutions in the paper, who also found that the severity of Covid-19 symptoms can determine the magnitude of the antibody response.

The new study included samples collected from 65 patients with confirmed Covid-19 up to 94 days after symptoms began to show and from 31 health workers who had antibody tests every one to two weeks between March and June.

Since the start of the pandemic, the World Health Organization has warned that people who have had Covid-19 are not necessarily immune to contracting the virus again.

However, the new study had some limitations, including the fact that more research is needed to determine if similar results would emerge among a larger group of patients and what data could be shown for longer periods of time when it comes to infection with the coronavirus, called SARS-CoV -2.

“This study has important implications when considering protection against reinfection with SARS-CoV-2 and the durability of vaccine protection,” the researchers wrote in the document.

What this means for a Covid-19 vaccine

Although not yet peer-reviewed, “the importance of this study is clear and the research has been rigorously conducted,” said Stephen Griffins, associate professor at the University of Leeds School of Medicine in the UK, who He was not involved in the new study, he said in a written statement distributed by the UK-based Science Media Center on Monday.
WHO says no evidence shows that having a coronavirus prevents a second infection.

“This work confirms that protective antibody responses in those infected with SARS-COV2, the coronavirus that causes COVID-19, appear to decrease rapidly. While it is more durable in those with more severe disease, this is only a matter of months,” Griffins said. said.

“Similar short-term responses are seen against other human coronaviruses that predominantly cause only mild disease, meaning that we can re-infect ourselves over time and outbreaks can adopt seasonality. With the most severe results, sometimes fatal from SARS-COV2, this is really concerning, “Griffins said. “Vaccines under development will need to generate stronger and longer-lasting protection compared to natural infection, or they may need to be administered regularly.”

As of Monday, there were 23 Covid-19 candidate vaccines under clinical evaluation globally, according to the WHO.
“Even if you don’t have detectable circulating antibodies, that doesn’t necessarily mean that you don’t have protective immunity because you likely have memory immune cells (B and T cells) that can quickly kick in to initiate a new immune response if you are reunited with the Then you could get a milder infection, “said Dr. Mala Maini, a professor of viral immunology and a consulting physician at University College London in the United Kingdom, in a statement also distributed by Science Media. Center on Monday.
B cells make antibodies to neutralize infectious microbes, like a virus, and T cells attack the infection directly and help control the immune response. When a person has been previously infected, those cells can remember the infection and boost the immune response, leading to possibly less severe reinfection than otherwise.

“But this study reinforces the message that we cannot assume that someone who has had COVID-19 cannot get it again just because they initially tested positive for the antibody,” said Maini, who was not involved in the study. “It also means that a negative antibody test now cannot exclude that you had COVID-19 a few months ago. And it suggests that vaccines will need to be better at inducing high levels of antibodies that last longer than natural infection or that doses may need be repeated to maintain immunity. “

‘Incomplete, transitory and then disappear’

The new paper adds to a growing body of evidence suggesting that natural immunity to Covid-19 with antibodies may not last as long as expected, and that the level of severity of initial coronavirus infection may be related to the magnitude of the antibody response.

68% of patients in a New York clinic test positive for antibodies against the coronavirus

In June, a small study found that people who have coronavirus infections but who never develop symptoms may have weaker immune responses to the virus.

That study, published in the journal Nature Medicine, found that a group of about three dozen Covid-19 patients who were asymptomatic had antibody levels that were significantly lower than what was found among patients who had mild symptoms, a finding suggesting that asymptomatic patients had weaker immune responses.
Then last week, a Spanish government study found that only 5% of people in Spain have antibodies to the coronavirus, and in a potentially worrisome development, the study also indicated that people’s immunity to the coronavirus declines after a few weeks. The results show that 95% of the Spanish population is still susceptible to the virus.

This means that any perceived immunity “may be incomplete, transitory and then disappear,” Dr. Raquel Yotti, director of the Carlos III Health Institute, a key government agency leading the study, said at a press conference.

The study “reflects the difficulty of obtaining collective immunity in the short term,” the Ministry of Health said in a statement. Herd immunity is achieved when a sufficient population has been infected with, or vaccinated against, a virus or bacteria to stop its circulation.

Spain’s April-June study involved more than 61,000 participants, which the European Center for Disease Prevention and Control told CNN that it appears to be the largest to date in Europe.

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