Antibodies to the common cold coronavirus do not protect against SARS-CoV-2

Past exposure to the cold-causing seasonal coronavirus (CoV) does not result in the production of antibodies that protect against the new coronavirus SARS-CoV-2, according to a study led by Dr. Scott Hensley School of Medicine, University of Pennsylvania. Microbiology.

Previous studies have suggested that recent exposure to seasonal CoV protects against the COVID-19-causing virus SARS-CoV-2. However, according to a survey by Hensley’s team, Was announced in cell, If there is such protection, it suggests that it is not derived from antibodies.

“Many people had antibodies that could bind SARS-CoV-2 before the pandemic, but these antibodies couldn’t prevent the infection,” Hensley said. “Antibodies from previous coronavirus infections cannot prevent SARS-CoV-2 infection, but existing memory B and T cells provide some protection or at least reduce the severity of COVID-19. It’s possible. It needs to be completed to test that hypothesis. “

Researchers examined blood samples collected from hundreds of people before the pandemic. They have “cross-reactive” anti-CoV antibodies in which more than 20% of these pre-pandemic samples can bind not only to the common cold-causing CoV, but also to the major sites of SARS-CoV-2. I found that there is. However, these cross-reactive antibodies were unable to neutralize the infectivity of SARS-CoV-2 and were not associated with better results in those who later acquired COVID-19.

Scientists have also found from blood tests in different groups that both children and adults tend to have on average the same level of cross-reactive anti-CoV antibodies. This means that these antibodies are not a factor in providing protection against severe COVID-19 in most children. ..

The COVID-19 pandemic has reported more than 100 million infections after more than a year of worldwide spread, of which more than 2 million have been fatal. Some risk factors, such as age, are well-clear, but scientists still explain why some people get fatal illness with COVID-19 and others escape without mild illness or symptoms. I don’t fully understand.

Antibodies have been considered one possible explanation. The common cold-causing type of seasonal coronavirus has long circulated in the population. A clear hypothesis is that some of these common infection-induced antibodies cross-react with the new coronavirus SARS-CoV-2, providing at least some protection against severe COVID-19 disease. That is.

A series of analyzes conducted by Hensley and colleagues examined blood samples collected from 263 children at the Philadelphia Children’s Hospital and 168 adults at the Pennsylvania Biobank. Samples were taken in 2017, more than two years before the SARS-CoV-2 pandemic began.

Researchers have found that most of the 431 samples contain antibodies to normal seasonal CoV. Some samples (approximately 20%) contained SARS-CoV-2 and “cross-reactive” anti-CoV antibodies, and the outer peplomer and / or nucleocapsid protein (the two most accessible coronas). It binds firmly to the site of viral protein). The immune system of the infected host.

Hensley et al. Separated blood samples stored prior to the pandemic from a control group of 251 who later tested positive for SARS-CoV-2 and 251 who matched age and other related characteristics. I analyzed it. New coronavirus. Again, they found that over 20% of pre-pandemic samples contained anti-CoV antibodies that could cross-react with SARS-CoV-2 spikes and / or nucleocapsid proteins. did. However, it means that similar proportions of infected and uninfected groups had these cross-reactive antibodies and did not provide protection against SARS-CoV-2 infection. In addition, in the group later infected with SARS-CoV-2, levels of cross-reactive anti-CoV antibody in pre-pandemic blood samples did not correlate with measurements of COVID-19 severity such as need. .. Hospitalization or ICU care.

In a third series of tests, researchers analyzed blood samples from 27 hospitalized COVID-19 patients and found that their cross-reactive anti-CoV antibody levels were strongly boosted during the course of COVID-19 disease. I found.

Researchers recommend conducting larger studies to unequivocally address the question of whether existing anti-CoV antibodies can protect against the SARS-CoV-2 virus. They also suggest that further studies examine other types of immune responses, such as T cell responses, to see if they provide a measure of cross-reactivity protection after seasonal CoV infection. There is.

However, in the meantime, their results suggest that shared sites where some antibodies bind to both seasonal coronavirus and SARS-CoV-2 are not vulnerable sites that can neutralize SARS-CoV-2. They say they are.

Reissued in courtesy of the University of Pennsylvania School of Medicine.