WASHINGTON -- Dr. Anthony Fauci, the nation's leading infectious disease expert, said a new study could explain the extraordinary range that people experience with the novel coronavirus, from having no symptoms at all or a mild case to hospitalization or death.
The discovery, which found potential signs of immunity in people who had previously been exposed to other types of coronavirus, could also expand the hunt for a long-lasting COVID-19 vaccine.
Fauci and other scientists said the study published in Science this month held promising findings for understanding why some individuals exposed to COVID-19 for the first time have a modest reaction to the virus.
The study found that the immune systems of roughly half of its subjects appeared to remember past exposure to other prevalent coronaviruses, including variants of the common cold, equipping them to respond more quickly to a COVID-19 infection once it appeared.
The findings also offer new insights that could help in developing a vaccine by looking at T cells, which help fight the virus.
Currently, all major candidates for a coronavirus vaccine undergoing clinical trials focus on harnessing a single antibody protein that can neutralize the virus.
Since the coronavirus outbreak began, scientists including Fauci have struggled with the question of why the novel coronavirus hits some people so hard and leaves others unscathed.
"One of the things that I don't think has been emphasized very much at all during the attempt to address, scientifically, the COVID-19 outbreak, and vaccine development and testing, is that we've been focusing very exclusively on the antibody test," Fauci told McClatchy in a recent interview. "There's another equally important component of the immune system."
The study, funded by the National Institute of Allergy and Infectious Diseases, which Fauci heads, is one of the first to identify T cell "cross reactivity" in individuals who have previously been exposed to one of the four endemic coronavirus strains, SARS or MERS.
T cells, which originate in the thymus, serve as a secondary line of defense in the immune system once antibodies have failed or faded away.