A new U.K. study suggests that antibodies in those who have been infected with Covid-19 could drastically decline in the body after only a few months.
The body creates antibodies, which are proteins, to fight off infection. According to the US Centers for Disease Control and Prevention, it can take one to three weeks to make antibodies after infection.
Antibodies are produced by B cells to neutralize infectious microbes, such as a virus. T cells act as the defense, attacking the infection directly, and helping control the immune response. If an individual has been infected before, those cells may remember the infection and activate a swift immune response, which would lead to re-infection being less severe than the initial infection.
“Even if you’re left with no detectable circulating antibodies, that doesn’t necessarily mean you have no protective immunity because you likely have memory immune cells (B and T cells) that can rapidly kick into action to start up a new immune response if you re-encounter the virus. So you might get a milder infection,” Dr. Mala Maini, professor of viral immunology and consultant physician at the University College London in the United Kingdom, said in a statement on Monday. He was not involved with the study.
The findings of the United Kingdom study released on Saturday to the medical server medrxiv.org, states that antibody responses may start to decline just 20 to 30 days after Covid-19 symptoms first appear.
This latest study included samples collected from 65 confirmed Covid-19 patients up to 94 days after they began showing symptoms and 31 health care workers who had antibody tests every one to two weeks between March and June.
“We show that IgM and IgA binding responses decline after 20-30 days,” the researchers from several institutions in the United Kingdom wrote in the paper. “This study has important implications when considering protection against re-infection with SARS-CoV-2 and the durability of vaccine protection,” the report states.
Stephen Griffins, associate professor at the University of Leeds School of Medicine in the United Kingdom, said that “the importance of this study is clear and the research has been rigorously undertaken,” though, he was not involved in the new study.
“This work confirms that protective antibody responses in those infected with SARS-COV2, the coronavirus that causes COVID-19, appear to wane rapidly. Whilst longer-lasting in those with more severe disease, this is still only a matter of months,” Griffins went on to say.
Dr. Maini, who was also not involved in the study, said that these latest findings help dismantle many false assumptions about the virus.
“But this study does reinforce the message that we can’t assume someone who has had COVID-19 can’t get it again just because they initially became antibody positive. It also means a negative antibody test now can’t exclude you having had COVID-19 a few months ago. And it suggests vaccines will need to be better at inducing high levels of longer-lasting antibodies than the natural infection or that doses may need to be repeated to maintain immunity.”