The immune response generated by previous exposure to common colds could protect against Covid-19, according to a new peer reviewed study published in Nature Communications Monday, an early but promising finding researchers say could pave the way to more long-lasting vaccines that protect against current and future variants of coronavirus.
People with high levels of T cells—a type of white blood cell that is a key part of the immune system—from other coronavirus infections like the common cold are less likely to contract the virus that causes Covid-19, according to a study by researchers at Imperial College London.
For the study, which took place in September 2020 (before most in the U.K. had been infected or vaccinated against Covid-19), the researchers followed 52 people living with someone who had Covid-19, half of whom went on to contract the disease.
For the half that did not get infected, blood samples taken shortly after exposure revealed higher levels of T cells from previous coronavirus infections, such as colds, that could also recognize proteins in the virus that causes Covid-19, the researchers said.
Professor Ajit Lalvani, the study’s senior author, said the findings provide “the clearest evidence to date that T cells induced by common cold coronaviruses play a protective role against” Covid and could hold the key to developing a universal vaccine that protects against current and future variants
The study said the T Cells attack proteins inside the virus, rather than the spike protein (targeted by most widely-used vaccines) on its surface, which Lalvani said mutate much less and make for more “broadly protective vaccines” between various variants.
While not all people who are exposed to Covid become infected, the precise mechanism behind this is not clear. Broader immune responses to Covid, such as those with previous coronavirus infections, have also indicated a more nuanced role of immunity than we currently understand. While the finding is an important one, first author Dr. Rhia Kundu said “it is only one form of protection… that no one should rely on” alone. Kundu said the best way to protect against Covid-19 “is to be fully vaccinated, including getting your booster dose.”
The role of T cells could be important. They last in the body far longer than the antibody responses after vaccination, which diminish after months. Lalvani, according to the Telegraph, said a vaccine provoking a T cell response across variants could cut down the need for boosters. We’re in this awful position where we need boosters every three months, but with T cells you could cut it down to every year or two years.”
WHAT TO WATCH FOR
Scientists in the U.S. Army are developing a Covid-19 vaccine designed to protect against current and future variants. The experimental shot uses multiple spike proteins to prime the immune system to recognize many types of coronavirus. Results from early human trials are expected within weeks.
Cross-reactive memory T cells associate with protection against SARS-CoV-2 infection in COVID-19 contacts (Nature Communications)
By Robert Hart, Forbes Staff