By Suherman Candra Maholtra 
The medical community has long recognized that respiratory viruses like influenza and SARS-CoV-2 cause immediate, often devastating, damage to the pulmonary system. However, a groundbreaking study from the UVA School of Medicine suggests that the consequences of these infections may extend far beyond the initial recovery period. Researchers at the Beirne B. Carter Center for Immunology Research and the UVA Comprehensive Cancer Center have identified a significant link between severe respiratory infections and the subsequent development of lung cancer. The study, recently published in the prestigious scientific journal Cell, reveals that the biological aftermath of a severe illness can create a fertile environment for tumors to take root and progress rapidly. Crucially, the research also highlights the role of vaccination as a powerful preventive measure, not just against the virus itself, but against the long-term oncogenic changes it triggers in the lungs.
A New Understanding of Viral-Induced Lung Malignancy
The research, led by Jie Sun, PhD, co-director of the Carter Center and a member of the UVA Division of Infectious Diseases and International Health, provides a sobering look at how the body’s immune response to a severe infection can be hijacked by cancer. For decades, the primary known risk factors for lung cancer have been environmental, such as tobacco use, radon exposure, and air pollution. While these remain critical, the UVA study suggests that biological "scars" left by severe viral pneumonia—whether caused by COVID-19 or the flu—must now be considered a significant factor in a patient’s long-term risk profile.
According to Dr. Sun, a severe case of COVID-19 or influenza can leave the lungs in a state of chronic, low-grade inflammation. This persistent "inflamed" state essentially prepares the ground for cancer cells. When the immune system is forced to respond to an overwhelming viral load, it can undergo fundamental changes that persist long after the virus has been cleared. These changes, the study found, can support tumor growth months or even years after the patient has been discharged from the hospital.
The Biological Mechanism: How Immune Cells Become Pro-Tumor
To understand the underlying mechanics of this phenomenon, the research team conducted extensive experiments using both laboratory mouse models and retrospective data from human patients. The findings pointed toward a specific shift in the behavior of immune cells, particularly neutrophils and macrophages. Under normal circumstances, these cells are the body’s first line of defense, identifying and destroying pathogens or early-stage cancer cells.
However, in the wake of a severe respiratory infection, these cells can become "reprogrammed." The study observed that some neutrophils began behaving abnormally, contributing to a "pro-tumor" environment rather than an anti-tumor one. Instead of patrolling the lungs to eliminate threats, these altered immune cells created an inflammatory milieu that actually facilitated the survival and proliferation of malignant cells.
Furthermore, the researchers identified significant alterations in the epithelial cells—the specialized cells that line the lungs and the alveoli (air sacs) where oxygen exchange occurs. The damage caused by the virus forces these cells into a state of constant repair and regeneration. In this high-turnover environment, the likelihood of genetic mutations increases, and the surrounding inflammatory signals from the altered immune cells provide the perfect conditions for these mutations to evolve into aggressive tumors.
Analyzing the Data: The 1.24-Fold Risk Increase
The human data component of the study was particularly revealing. By analyzing large-scale patient records, the team found a clear statistical correlation between hospitalization for COVID-19 and a subsequent diagnosis of lung cancer. The analysis revealed a 1.24-fold increase in lung cancer incidence among patients who had suffered severe COVID-19 compared to those who had not.
Perhaps most significantly, this elevated risk was observed across all demographics, independent of smoking history or other preexisting medical conditions (comorbidities). While smokers are already at a baseline higher risk for lung cancer, the addition of a severe respiratory infection acted as a compounding factor. For non-smokers, the infection introduced a risk factor where there previously was very little.
The study noted a distinct difference between severe and mild infections. Patients who experienced only mild symptoms of COVID-19 or the flu did not show an increased risk of lung cancer. In some instances, those with mild infections actually showed a slight decrease in cancer incidence, suggesting that a controlled, effective immune response may actually bolster the body’s surveillance against tumors. The danger lies specifically in the "overdrive" response associated with severe, hospitalized cases.
The Protective Role of Vaccination
One of the most vital takeaways from the UVA research is the secondary benefit of vaccination. While vaccines are designed to prevent acute illness and death, this study suggests they also serve as a preventive measure against cancer. By preventing an infection from becoming "severe," vaccines effectively block the cascade of immune changes that lead to a pro-tumor environment.
Dr. Sun and his team observed that individuals who were vaccinated prior to infection did not exhibit the same long-term immune scarring seen in the unvaccinated. Because the vaccinated immune system can recognize and neutralize the virus more efficiently, the lungs are spared the extensive tissue damage and chronic inflammation that characterize severe pneumonia.
"The encouraging news is that vaccination largely prevents those harmful changes for cancer growth in the lung," Dr. Sun noted. This adds a new layer to public health messaging regarding the flu and COVID-19 vaccines. They are no longer just tools for preventing a week of illness; they are potentially life-saving interventions that reduce the long-term risk of one of the world’s deadliest cancers.
Clinical Implications and the Need for Enhanced Screening
The findings have immediate implications for how the medical community manages post-viral recovery. Jeffrey Sturek, MD, PhD, a UVA physician-scientist and collaborator on the study, emphasized the need for a shift in clinical monitoring. Currently, routine lung cancer screening—typically via low-dose CT scans—is recommended primarily for long-term smokers over a certain age.
Dr. Sturek suggests that severe respiratory viral infection should be viewed as a similar risk marker. "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," Sturek stated.
In practice, this could mean that a patient who was intubated or hospitalized for severe pneumonia might eventually be added to the list of candidates for regular lung screenings, regardless of their smoking status. Early detection remains the most critical factor in lung cancer survival; catching a tumor at Stage 1 rather than Stage 4 dramatically changes the prognosis. By identifying severe infection survivors as a high-risk group, doctors can catch "viral-triggered" cancers at a treatable stage.
Broader Public Health Context and Global Impact
With tens of millions of people worldwide having survived severe bouts of COVID-19 since 2020, the potential public health impact of this study is vast. The researchers describe "long-term pulmonary sequelae"—the lingering effects of lung injury—as a looming challenge for healthcare systems. If even a small percentage of severe COVID-19 survivors develop lung cancer due to immune reprogramming, it could lead to a noticeable uptick in global cancer rates in the coming decade.
This research also places respiratory viruses in a category with other known oncogenic (cancer-causing) viruses. For example, the Human Papillomavirus (HPV) is a known cause of cervical cancer, and Hepatitis B and C are primary drivers of liver cancer. While those viruses cause cancer through different biological pathways, the UVA study confirms that respiratory viruses can also be oncogenic, albeit through the indirect route of chronic inflammation and immune system alteration.
Advancing Research at UVA’s Manning Institute
The study is a testament to the collaborative research environment at the University of Virginia. Much of the work was supported by the Paul and Diane Manning Institute of Biotechnology, which focuses on accelerating the transition of laboratory findings into clinical treatments. By bridging the gap between basic immunology and oncology, the team was able to identify a connection that might have been missed in more siloed research environments.
The UVA Comprehensive Cancer Center, one of only 57 centers in the U.S. to hold the National Cancer Institute’s "comprehensive" designation, provided the clinical framework necessary to validate the mouse-model findings with human data. This multidisciplinary approach is essential for tackling complex diseases like lung cancer, which involve intricate interactions between pathogens, the immune system, and genetics.
Future Directions: Targeted Prevention and Treatment
Looking forward, Dr. Sun and his colleagues are interested in developing targeted therapies that can "reset" the immune system after a severe infection. If scientists can identify the specific signals that cause neutrophils to become pro-tumor, they may be able to develop drugs that intervene during the recovery phase, essentially "erasing" the immune scar before cancer has a chance to develop.
"Our goal is to help doctors identify who may be at higher risk of lung cancer after a severe infection, and develop targeted ways to prevent and treat lung cancer after prior pneumonia," Sun said. This research marks the beginning of a new field of study: post-viral oncology.
As the world continues to navigate the aftermath of the COVID-19 pandemic and prepares for future flu seasons, the message from UVA is clear. Prevention through vaccination remains the most effective strategy. For those who have already suffered through a severe respiratory illness, the study offers a roadmap for vigilance, emphasizing that the path to long-term health involves monitoring the lungs long after the cough has subsided.
The research was supported by numerous grants from the National Institutes of Health (NIH), as well as private fellowships and foundational support, highlighting the high level of scientific interest in the long-term consequences of the viruses that define our modern era. The full findings, titled "Severe respiratory viral infection induces a chronic pro-tumor immune microenvironment," are now available for the global scientific community to review in the journal Cell.
