That’s because seasonal common colds caused by coronaviruses may teach our bodies how to fight similar infections, including the coronavirus that causes COVID-19, according to a study from Boston University published last week.
Scientists found that patients who had experienced a cold caused by a coronavirus in the past five years and who later contracted COVID-19 had less severe COVID-19 symptoms, and were significantly less likely to be admitted to an intensive-care unit, require a ventilator, or die, than those who hadn’t had that type of cold before.
“These study results could help identify patients at lower and greater risk of developing complications after being infected with (the novel coronavirus),” Prof. Joseph Mizgerd, one of the study’s authors, said in a news release.
The researchers gleaned data from electronic medical records for 15,928 adult patients at Boston Medical Center who’d had a test for a common cold coronavirus between May 18, 2015 and March 11, 2020, as well as data from 1,812 patients who were hospitalized with COVID-19 between March 12 and June 12, 2020.
They noted that having experienced a coronavirus cold does not make you immune to COVID-19, but rather only has the potential to lessen your symptoms.
The study builds off previous research that helps explain why people respond so differently to the novel coronavirus — from being asymptomatic to experiencing mild COVID-19 symptoms to dying from respiratory infections and other complications. It also helps explain why some areas are hit harder by COVID-19 than others, depending on the population’s exposure to other coronaviruses.
More than 200 viruses can cause a common cold, including four types of coronaviruses that cause upper respiratory tract infections. However, rhinoviruses are the most common causes of colds.
A study led by La Jolla Institute researchers in California found that 40 to 60 per cent of people never exposed to the novel coronavirus still had an immune response to it, thanks to T cells. The study said that research from the Netherlands, Germany, Singapore and the United Kingdom has found similar trends.
Our immune system’s T cells patrol our bodies looking to destroy infected cells and stop a virus from multiplying. People who had experienced a coronavirus cold developed T cells that recognized the similar novel coronavirus and attacked, researchers found.
These T cells have the potential to remain in our bodies for years, suggesting immunity to the novel coronavirus could last a long time, too. A study from a medical school in Singapore found T cells that attack the virus that causes severe acute respiratory syndrome (SARS) remained in patients 17 years after infection.
Scientists said that while more research is needed, these early discoveries will help them develop more potent vaccines, better understand clinical outcomes and influence herd immunity models.
Correction: This story was updated with the correct name of the hospital where researchers accessed patient data, which was Boston Medical Center.