Study: Post-infection COVID immunity usually robust after 8 months
The human body typically retains a robust immune response to the coronavirus for at least eight months after an infection, and potentially much longer, researchers said in a study published in the journal Science. About 90% of the patients studied showed lingering, stable immunity, the study found.
The coronavirus has been shrouded in unknowns and uncertainties since it emerged a little more than a year ago, and one of the biggest questions has been whether people can get reinfected, and if so, how quickly. There have been isolated reports of people having a second case of covid-19, the disease caused by the virus, but that appears to be rare, and the new study bolsters the case that immunity usually persists.
The review of blood samples from nearly 200 patients also saw that multiple elements of the immune system – not just antibodies – continued to be effective at recognizing and responding to the virus. The human body appears to retain a memory of the invader and is poised to generate a coordinated counterattack of antibodies and killer T cells quickly if exposed again.
This comes amid concerns about mutant variants of the coronavirus, including one originally identified in the United Kingdom and spreading rapidly there. As of Thursday afternoon it had been seen in seven states in the United States, including two new additions, Texas and Pennsylvania.
Scientists have been generally optimistic that these variants will be unable to escape the onslaught of the human immune system. But officials at the Centers for Disease Control and Prevention are ramping up a strain surveillance program to improve the genomic sequencing that allows scientists to study mutations.
The authors of the new study said they believe their findings would apply to the United Kingdom variant as well as the more common coronavirus. The reason: The immune responses target hundreds of different pieces of the virus, few of which are affected by the current mutations. The consensus is that the coronavirus would need a tremendous number of mutations in concert to evade natural or vaccine-induced immunity.
“There’s a lot of different arms of the immune system recognizing the virus. so if you have a mutation, it wouldn’t evade all these different arms,” said Daniela Weiskopf, a co-author of the study and a researcher at the La Jolla Institute for Immunology.
The immune response to a virus builds gradually, peaks, then begins to contract - but can reach a plateau, and stay there for a long period. After eight months, Weiskopf said, most people who have been infected by the coronavirus and have recovered appear to have stable immunity.
“It’s not decaying any further. Based on that, it might be good for many more months, or years,” Weiskopf said.
This has to remain speculative for now, because the novel coronavirus has been circulating in human beings for barely a year and there isn’t long-term data. The oldest specimens studied by the La Jolla team were from March, Weiskopf said.
The full duration of immunity is speculative because the novel coronavirus has been circulating in human beings for barely a year and there isn’t long-term data. The oldest specimens studied by the La Jolla team were obtained about nine months ago, Weiskopf said.
Stanley Perlman, a University of Iowa virologist who was not part of the research team, said the study is welcome news given that some early reports last spring suggested that immunity to the coronavirus might wane quickly.
“This is more believable, and this is done well. This supports the notion that there’s going to be immunity for some period of time,” Perlman said.
It is still possible for someone with immunity to get infected by the coronavirus without becoming sick, Perlman noted. The immune response is unlikely to be sterilizing. “People get infected, but they don’t get affected,” he said.