ALARMING Discovery: Flu Creates Lifelong Cancer Risk

A new University of Virginia study reveals that severe COVID-19 or influenza infections reprogram your lung cells, creating a cancer-friendly environment that persists for months or even years after recovery—raising lung cancer risk by 24% regardless of smoking history.

Story Snapshot

Severe respiratory infections trigger long-lasting immune cell changes that increase lung cancer risk 1.24-fold, independent of smoking or other health conditions
Research shows neutrophils and macrophages reprogram into “pro-tumor” states after hospitalization for COVID-19 or flu, creating inflammation that fuels cancer development
Vaccination against these viruses prevents severe infection and the resulting immune scarring, offering indirect protection against future lung cancer
Scientists recommend enhanced CT screening for survivors of severe respiratory infections, similar to protocols used for longtime smokers

Immune System Reprogramming Creates Cancer Risk

University of Virginia researchers discovered that severe COVID-19 and influenza infections fundamentally alter lung immune cells, transforming them into cancer-promoting agents. Dr. Jie Sun and his team at UVA’s Beirne B. Carter Center for Immunology Research found that neutrophils and macrophages—cells normally responsible for fighting infection—become reprogrammed during severe respiratory illness. These altered immune cells create a persistently inflamed environment in lung tissue that favors tumor development. The study, published in the journal Cell in March 2026, demonstrates this process through both laboratory mice experiments and analysis of human patient hospitalization records.

The research team exposed mice to severe influenza infections and tracked their health outcomes over extended periods. Mice that survived serious flu infections developed lung cancer at significantly higher rates than those with mild cases or no infection. The severity of the initial infection proved critical—only hospitalization-level respiratory illness triggered the dangerous immune reprogramming. Interestingly, mild cases of COVID-19 or flu showed a slight protective effect against lung cancer, highlighting that infection severity determines whether the immune response helps or harms long-term health.

24% Higher Cancer Risk Independent of Traditional Factors

Analysis of human patient data confirmed the laboratory findings with sobering statistics. Individuals hospitalized for severe COVID-19 or influenza face a 1.24-fold increased risk of developing lung cancer months or years after recovery. This elevated risk exists independently of traditional cancer risk factors like smoking history, age, or pre-existing health conditions. The findings carry particular weight given that tens of millions worldwide experienced severe respiratory infections during the COVID-19 pandemic. Dr. Jeffrey Sturek, a physician-scientist collaborator on the study, emphasizes that the immune system changes persist long after patients recover from acute illness, creating an ongoing vulnerability.

The mechanism behind this increased cancer risk involves changes to epithelial cells lining the lung’s air sacs. During severe infection, the combination of viral damage and reprogrammed immune cells creates what researchers describe as “immune scarring.” This altered state doesn’t resolve when the infection clears. Instead, the inflammatory environment persists, providing conditions where cancerous cells can more easily establish themselves and grow. The research reveals a previously unrecognized long-term consequence of severe respiratory illness that extends far beyond the immediate health crisis.

Vaccination Offers Protection Against Future Cancer Risk

The study provides compelling evidence that vaccination against COVID-19 and influenza delivers benefits beyond preventing immediate illness. Dr. Sun’s team found that vaccination largely prevents the harmful immune cell reprogramming that leads to elevated cancer risk. By reducing the likelihood of severe infection requiring hospitalization, vaccines eliminate the trigger for these dangerous long-term changes. This represents an indirect but significant form of cancer protection that hasn’t been widely recognized in public health discussions. The findings validate vaccination as a tool for preventing not just acute respiratory illness but also its hidden long-term consequences.

Dr. Sturek recommends treating severe respiratory infection history similarly to smoking when determining lung cancer screening protocols. Patients who survived hospitalization for COVID-19 or influenza should receive enhanced surveillance through CT scans, particularly if they have additional risk factors like smoking history. This proactive approach could catch cancers earlier when they’re most treatable. The research team’s recommendations emerge as healthcare systems continue managing the pandemic’s aftermath, with implications for millions of survivors who may face elevated cancer risk without knowing it. These findings underscore why preventing severe infection through vaccination matters far beyond the immediate crisis.