By George Citroner
Scientists have puzzled over why some people seem immune to COVID-19, even after exposure. Now, emerging evidence points to an intriguing explanation: prior run-ins with the common cold.
Common Cold Antibodies Protect Against COVID
A new study investigated whether preexisting antibodies from common cold viruses offer protection against COVID-19. Researchers analyzed blood samples from 94 unvaccinated hospitalized patients with varying severity of respiratory failure; 74 had tested positive for COVID-19, while 20 did not have the infection.
They measured levels of antibodies from prior common cold coronavirus infections. The same analysis was done for non-COVID patients as controls.
There was a positive correlation between common cold antibody levels and COVID-specific antibodies. Higher common cold antibody levels in the control patients suggested a potentially protective effect against COVID severity.
‘Original Antigenic Sin’
The concept of “original antigenic sin” (OAS) was first coined in the 1960s. It refers to how initial flu exposures shape immunity against later, related strains.
Since then, research has shown these original imprints can influence susceptibility to other infections.
This phenomenon may also apply to COVID-19 and common colds, Dr. Thomas Gut, an internal medicine doctor with the Post-COVID Recovery Center at Staten Island University Hospital, told The Epoch Times.
“It’s been up for debate for quite some time whether preexisting colds … offer a protective effect for being exposed to COVID or whether it somehow makes it higher-risk when they’re exposed to COVID,” he said.
These latest findings suggest that any prior corona-type virus—the common cold or COVID—is unlikely to heighten susceptibility, Dr. Gut added.
Did Childhood Colds Help Africa Evade COVID’s Worst?
There is an intense debate around whether endemic common colds impact susceptibility to severe COVID outcomes, according to a review of the study. But some speculate childhood cold exposure partly explains Africa’s milder pandemic impact through cross-protection.
A 2023 study in the Journal of Clinical Virology Plus analyzed “robust” immune responses to COVID-19 in Lagos, Nigeria. Researchers examined two groups: health care workers and the general population across five areas.
Of the 250 participants, over 83 percent had prior exposure to common cold coronaviruses. The study found their infection-fighting white blood cells cross-reacted to the COVID-19 virus.
This suggests that people who were previously exposed to these genetically related coronaviruses have immune responses that are protective against future SARS-CoV-2 infections, Bobby Brooke Herrera, assistant professor of global health at Rutgers Global Health Institute and lead author of the study, said in a press statement. He noted the study’s unique baseline data from early in the pandemic before vaccination started.
Now that most people have existing COVID antibodies, either from vaccination or infection, it’s difficult to find an unexposed population for comparison, underscoring the value of early pandemic data.
Early Exposures Shape Kids’ Viral Defenses: Study
A 2023 study in Proceedings of the National Academy of Sciences analyzed pre-pandemic blood samples from children and adults, along with samples from COVID-19 recoverees.
The research found children as young as 2 had already developed immunity to several viruses, including SARS-CoV-2, the virus that causes COVID-19. However, these protective cells decreased with age.
“These reactions are especially strong early in life and grow much weaker as we get older,” Annika Karlsson, study corresponding author and research group leader at the Department of Laboratory Medicine, Karolinska Institutet, said in a press statement.
This may explain why children tend to get milder COVID-19 cases than adults.