[Newsphopick=Gyubin Lee] After people are infected with the novel coronavirus, their natural immunity to the virus could decline within months, a new pre-print paper suggests. The paper, released on the medical server medrxiv.org on Saturday and not yet published in a peer-reviewed medical journal, suggests that antibody responses may start to decline 20 to 30 days after Covid-19 symptoms emerge. Antibodies are the proteins the body makes to fight infection.
"We show that IgM and IgA binding responses decline after 20-30 days," the researchers from institutions in the United Kingdom wrote in the paper, which 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 they started showing symptoms and from 31 health care workers who had antibody tests every one to two weeks between March and June.
In general, it can take one to three weeks after infection for your body to make antibodies, according to the US Centers for Disease Control and Prevention.
Since early on in the pandemic, the World Health Organization has warned that people who have had Covid-19 are not necessarily immune from getting the virus again.
Yet the new study had some limitations, including that more research is needed to determine whether similar results would emerge among a larger group of patients and what data could show over longer periods of time when it comes to infection with the coronavirus, named SARS-CoV-2.