A study published in Nature Communications found that while antibodies against SARS-CoV-2 may be a good way to measure exposure to the virus, their presence alone was not enough to determine if a person had long-lasting protection. Instead, antibody effector functions associated with long-lasting protection, like virus neutralization and T cell responses, were only seen if the immune response included high levels of antibodies against a part of the virus called the receptor binding domain.
The study was by Galit Alter, PhD, core member of the Ragon Institute of Massachusetts General Hospital, MIT and Harvard University.
The data came from a cohort of adults who had mild or asymptomatic cases of COVID-19 (unusual among the studies that started in the early days of the pandemic), the result of a collaboration with SpaceX, an aerospace manufacturer and space transportation services company that was seeking data-driven ways to protect its essential workforce.
Though the original goal of the study was to measure antibody levels over time, when reports of reinfection began surfacing, Alter’s team realized their samples may hold much more valuable information than they originally thought.
“In early spring, we weren’t sure if asymptomatic infection could drive long-lived antibodies,” says Alter, “nor whether they possessed the capability to neutralize or kill the virus.”
The team did know, however, that 120 of their study participants had experienced mild or asymptomatic COVID-19, resulting in the development of COVID-19 antibodies. By using sophisticated techniques to delve into these antibody responses, they discovered that individuals who had developed a larger number of antibodies, associated with stronger symptoms in case of mild COVID-19, had also developed immune functions associated with natural immune protection.
