A recent study highlights the significant role that infectious agents play in the development of chronic diseases, particularly cancer, challenging the notion that public health efforts should focus solely on non-communicable conditions. The research, published in Lancet Oncology, estimates that approximately 2.3 million new cancer cases worldwide—nearly one in eight—are linked to infections, many of which are preventable through vaccination or early treatment.

The study analyzed global cancer data from 2024 and identified 12 infectious agents known to cause cancer. Five pathogens were responsible for more than 99 percent of infection-related cancers. Helicobacter pylori, a bacterial infection commonly found in Asia, and human papillomavirus (HPV), which is associated with cervical, anal and oral cancers, accounted for over 1.5 million cases combined. Hepatitis B and C viruses, linked to liver cancer, and Epstein-Barr virus (EBV), associated with head and neck cancers, stomach cancer, and lymphoma, comprised the rest.

Vaccination programs have demonstrated effective prevention against several of these infections. The HPV vaccine, administered to children between ages 12 and 13, can prevent up to 90 percent of cervical cancers. Since its introduction, HPV infections have dropped by 88 percent among teenage girls in the United States. Similar benefits have been observed in the United Kingdom, where vaccinated girls have an 87 percent lower risk of developing cervical cancer. A related study found no cervical cancer deaths among vaccinated women by age 30. The hepatitis B vaccine, typically given at birth, provides lifelong protection and prevents at least 98 percent of infections when the full series is completed.

While there is no vaccine for Helicobacter pylori, testing and treatment can halt the chronic inflammation that leads to stomach cancer. This infection affects over half of the population in some regions and can be detected through breath or stool tests and treated with antibiotics and acid-reducing medication. Hepatitis C also lacks a vaccine, but antiviral medications can cure more than 95 percent of infections, reducing liver damage and transmission risk.

EBV presents greater challenges, as no vaccine or targeted treatment currently exists. In the United States, nearly all adults are infected by the virus, which usually causes mild symptoms but can remain dormant and later contribute to cancer and other diseases such as multiple sclerosis. Researchers call for intensified study into vaccine development and treatment options for EBV.

The authors of the study emphasize the importance of integrating infectious and chronic disease prevention strategies, rejecting the idea that these health issues should be addressed separately. They note that vaccines and preventive measures, such as condom use, could substantially reduce the global cancer burden. Beyond cancer, infections like influenza and respiratory syncytial virus have been linked to increased risks of heart attacks, strokes, and other cardiovascular diseases. Emerging evidence also suggests vaccines may offer additional health benefits, including lower rates of dementia and other chronic conditions.

While lifestyle factors such as diet and physical activity remain important for chronic disease prevention, the study underscores the substantial public health gains achievable by investing more in infectious disease research and vaccine coverage to address the infectious roots of many chronic illnesses.