Severe lung infections may boost lung cancer risk

Image representing Covid lung infection generated by Wix AI

CANCER DIGEST – March 16, 2026 – Scientists have discovered that serious viral lung infections that require hospitalization can alter immune cells in the lungs, leaving behind chronic inflammation that may help tumors develop months or years later, but that vaccination heads off those harmful effects.

The study led by Jie Sun, PhD at the University of Virginia Health looked at the harmful effects of severe Covid-19 and influenza infections in both mice and humans. Their findings were published in the March 15, 2026 journal Cell.

“A bad case of COVID or flu can leave the lungs in a long-lasting ‘inflamed’ state that makes it easier for cancer to take hold later,” Sun, co-director of UVA’s Carter Center and a member of UVA’s Division of Infectious Diseases and International Health said in a press release. “The encouraging news is that vaccination largely prevents those harmful changes for cancer growth in the lung.”

The researchers examined the effects of severe lung infections in both lab mice and humans. In the mice given severe infections from either Covid-19 or influenza they found that the infections accelerated lung cancer growth. 

In the infected mice serious viral lung infections had dramatic effects on immune cells called neutrophils and macrophages that are supposed to protect the lungs. These changes caused wayward neutrophils to begin creating an inflamed, “pro-tumor” environment where cancer can thrive.

In effect the infection reprogrammed the lung into a pro-tumor microenvironment with sustained accumulation of tumor-associated neutrophils and suppression of the immune system. However mice vaccinated against the infections blocked the accumulation of pro-tumor neutrophils and restored immune T cell function that suppresses tumor growth.

When the researchers examined data from patients hospitalized for Covid-19 or influenza, they found a 124-fold increase in lung cancer incidence. When they controlled for other factors that could play a role in increasing lung cancer, such as smoking or other health conditions, the risk did not change. As with the mice, however,  prior vaccination in patients appeared to prevent the cancer-promoting lung changes.

“These findings have important immediate implications for how we monitor patients after severe respiratory viral infection,” Jeffrey Sturek, MD, PhD, a UVA physician-scientist and collaborator on the project said in a press release. “We’ve known for a long time that things like smoking increase the risk for lung cancer. The results from this study suggest that we may need to think about severe respiratory viral infection similarly." 

Sun and his colleagues hope that their findings will ultimately lead to doctors identifying patients at increased risk of lung cancer due to severe viral infection that could result in earlier diagnosis and treatment.

Sources: UVA Health press release and the journal Cell