With all that’s happened in the past few months regarding the coronavirus, we could use a bit of good news. And that’s exactly what we have after a recent batch of studies showed that humans have a “robust” immune response to Covid-19 that may protect them from further infection, even if they had mild symptoms. 

One leading immunologist says the findings provide optimism that people will not have to endure repeated coronavirus infections. It also provides evidence a vaccine might protect people for more than a short time.

Early in the pandemic, some scientists questioned how long the body would remember the infection after contracting it and whether the body will continue to produce antibodies — the proteins the body makes to fight infection — to protect it. Previous studies showed these antibodies decline over time and different people produce different numbers of antibodies, but more recent studies are painting a different picture.

One of the studies showed that T cells appear to be activated by this novel coronavirus. T cells are important immune cells that stimulate various arms of the immune system and that also attack and kill cells already infected by a virus.

Another study that looked at donor blood samples found that a big part of the population, between 20% to 50% of people in some areas of the US, may have T cells that recognize the novel coronavirus, even if that person has never been infected. It’s still unclear why people have them. It may be what’s called cross-protection from other coronaviruses that cause the common cold. What scientists still don’t know is if this provides protection against Covid-19, but it has potential.

“So, this is very good news and it’s optimistic,” said Dr. Ian Lipkin, director of the Center for Infection and Immunity at Columbia University Mailman School of Public Health. “You know, it is a bit of blue sky that we’ve been looking for.”

Another study coming out from immunologist Marion Pepper’s work at the University of Washington showed that some of the T cells form memory T cells that can hang around and help provide protection in case a person encounters the novel coronavirus again. From studies that look at SARS, another coronavirus, research shows that the memory T cell response is long-lived. Since scientists have not seen a record of re-infection, even with as widespread as the pandemic is, the findings strongly suggest that the body’s immune system is working well against this threat, and re-infection is less likely.

Although more research needs to be done, these new findings raise hope that our bodies will be able to squash the coronavirus—hopefully, sooner rather than later.