A new study suggests that the body’s immune response to the novel coronavirus can last for at least eight months after the onset of symptoms from the initial infection.
The duration of immunity to Covid-19 has been a subject of research through the pandemic, and studies so far have provided various results. In July last year, a study suggested that immunity might be lost in months. As The Indian Express reported back then, researchers from King’s College London drew this conclusion from a drop they observed in the antibody levels in recovered Covid-19 patients over time — from a “potent level” in 60% of study participants during the peak of infection to only 16.7% retaining that level of potency 65 days later. While that study suggested that recovered Covid-19 patients are likely to remain susceptible to re-infection, the new study suggests that nearly all Covid-19 survivors have the immune cells necessary to fight re-infection.
The study, published in the journal Science, is based on analyses of blood samples from 188 patients. “Our data suggest that the immune response is there—and it stays,” Alessandro Sette of La Jolla Institute (LJI), who co-led the study with Shane Crotty and Daniela Weiskopf, said in a statement issued by LJI.
“We measured antibodies, memory B cells, helper T cells and killer T cells all at the same time. As far as we know, this is the largest study ever, for any acute infection, that has measured all four of those components of immune memory,” LJI quoted Crotty as saying.
The findings could mean that Covid-19 survivors have protective immunity against serious disease from the SARS-CoV-2 virus for months, perhaps years, after infection, the researchers said. Their study addresses concerns arising out of Covid-19 data from other labs, which showed a dramatic drop-off of Covid-specific antibodies over time.
As the researchers said, a decline in antibodies is very normal. “That’s what immune responses do. They have a first phase of ramping up, and after that fantastic expansion, eventually the immune response contracts somewhat and gets to a steady state,” Sette was quoted as saying.