A common cold from five years ago could be helping you fight the coronavirus, Fauci says.
One of the biggest questions amid the COVID-19 pandemic has been why does the virus kill some people and leave others without any detectable symptoms. Now, six months into the pandemic, we’re finally getting some answers. According to Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), if you’re someone who’s known to get the common cold year after year, you could have some protection against the novel coronavirus, thanks to the T cells in your immune system.
“If you look at [your immune system] metaphorically as an army with different levels of defense, the antibodies prevent the virus from getting in. So that’s kind of like the first line of defense,” Fauci told McClatchy in a recent interview. “For those viruses that do escape and infect some cells, the T cells come in and kill the cells that are infected or block them.”
Fauci said much of the research on COVID has been “focusing very exclusively on the antibody test,” but, he said, T cells are an “equally important component of the immune system.”
Because COVID-19 is a new coronavirus, it was initially believed that your T cells would not be able to detect it. It was assumed that T cells would only be found in people who have already had COVID-19. But a new NIAID study published in the journal Science on August 4 suggests that up to 50 percent of people who have not been exposed to the coronavirus have the T cells needed to fight the virus. Similarly, a German study published in the journal Nature at the end of July looked at 68 healthy people who had not yet been exposed to the coronavirus. Among them, 35 percent had the T cells in their blood needed to attack the novel coronavirus.
As a result of this new research, experts believe that healthy individuals may have generated these T cells when fighting similar infections from related coronaviruses in the past, like the common cold. And the more recently an individual was infected with another type of coronavirus, the greater the chances are that they have some protection from COVID-19, Fauci told McClatchy.
“It’s sort of like a one-two punch,” he said. “It’s conceivable that the T cells that you’ve made in response a couple of years ago—three, four, five years ago—when you were exposed to a relatively benign coronavirus that causes the common cold, could actually hang around, and when you’re exposed to the SARS-Coronavirus-2, could have some degree of protection,” he said.
Serving as a secondary line of defense in the immune system once antibodies have failed or faded away, T cells also last much longer than antibodies. So, if you’ve read those startling reports that antibodies don’t last—like a July study out of the United Kingdom that found that COVID antibodies declined after just three weeks from the start of the infection—worry not. These reports ignore the role of T cells, according to Fauci and other experts, which is just as pivotal.
Amesh Adalja, MD, senior scholar at the Johns Hopkins University Center for Health Security, told CNN that preexisting T cells may also help us understand why COVID affects people so differently.
“If you could compare people maybe with severe and mild illness and try and look at the T cells in those individuals and say, ‘Are people who have severe disease less likely to have cross reactive T cells versus people who have mild disease maybe having more cross reactive T cells?’ I think that there’s biological plausibility to that hypothesis,” he said. “It’s clear though that the T cell presence doesn’t prevent people from getting infected, but does it modulate the severity of infection? That’s what it appears could be the case.” And for more on this, check out This Is Why COVID Kills Some People and Others Are Symptom-Free, Study Says.