Could catching a common cold offer any protection against COVID-19? That’s what a small study conducted by researchers at the Imperial College of London set out to investigate. What their team of researchers discovered was this: those folks who had specific immune T cells after developing a cold appeared to be less likely to catch the COVID virus.

But don’t jump to any conclusions. Experts agree that this science isn’t simple and no one should rely on a cold to defend themselves against COVID. Instead, what the researchers are hoping is that their findings might help us to understand one way our body’s defense system fights COVID-19. In other words, why some people catch the virus after being exposed — while others do not.

Once a cold is no longer with us, not all infection-fighting T cells disappear. Some remain in our body to fight their next virus.

To do this, the study published in the journal Nature Communications concentrated on T cells. T cells develop in our bone marrow and are an important part of our immune system. They act to fight any infection, including a cold virus. But once the cold is no longer with us, not all infection-fighting T cells disappear. Some remain in our body and gear up to fight their next virus. These remaining cells are known as “memory” cells.

Starting in September 2020, before vaccines were available, the research team looked at 52 people who lived with others who had just gotten a positive result after testing for COVID-19. Half the group of cohabitants ended up contracting COVID, but the other half did not, and the researchers were interested in why that was.

Blood samples taken from the participants showed that one-third of those who did not get COVID had high levels of memory T cells in their blood, most likely created when their body was infected with the cold. “We found that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses like the common cold, can protect against COVID-19 infection,” Rhia Kundu, of Imperial’s Heart and Lung Institute and the study’s lead author, explained in a statement.

There are several limitations to keep in mind: The study used a very small sample of volunteers (only 52 people); and 88 percent of the participants were of white European ethnicity. What’s more, as Kundu and most other medical experts recommend, the best way for us to protect ourselves against COVID is still to be fully vaccinated and get a booster.

The study is published in Nature Communications.