In a twist that challenges conventional wisdom, the common cold may be playing an unlikely role in defending the human body against COVID-19. New research from National Jewish Health, part of a nationwide HEROS study, suggests that recent infections with rhinoviruses—the pathogens behind most colds—can trigger immune responses that temporarily protect against SARS-CoV-2.

The study tracked over 4,100 individuals across 1,394 households, focusing on children and adults exposed to respiratory viruses. Researchers found that those who had recently battled a rhinovirus were significantly less likely to contract COVID-19 in the following weeks. The key lies in a phenomenon known as heterologous viral interference, where one virus activates immune defenses that incidentally block another.

Rhinoviruses are known to stimulate a strong interferon response—proteins that act as the body’s early warning system against viral invaders. This immune activation appears to prime the airways, making it harder for SARS-CoV-2 to gain a foothold. Children, in particular, showed higher baseline expression of interferon-related genes, which may explain their generally milder COVID symptoms.

Dr. Max Seibold, senior author of the study, emphasized the significance: “The immune boost from a recent cold may give the body an early advantage in fighting SARS-CoV-2. This may help explain why children generally experience fewer and less severe COVID cases.”

However, researchers caution against drawing the wrong conclusions. “This doesn’t mean people should try to get sick,” said lead author Dr. Camille Moore. “But understanding how one virus affects the body’s response to another could help us develop new prevention strategies—especially for vulnerable populations.”

For Colorado families, educators, and healthcare providers, the findings offer insight into how everyday viral exposures shape immunity. As respiratory season approaches, this research may influence how we think about viral interactions, pediatric health, and community resilience.

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