Decades After Diagnosis, Childhood Cancer Survivors Still Vulnerable to Severe COVID: Study Shows - Video

A new study from Karolinska Institutet, published in The Lancet Regional Health-Europe, reveals that individuals who survived cancer during childhood are at a significantly higher risk of developing severe COVID-19 even decades after their diagnosis and treatment.

In this large registry-based study, researchers set out to examine how adult survivors of childhood cancer in Sweden and Denmark were affected during the COVID-19 pandemic.

The study included data from more than 13,000 people who were diagnosed with cancer before the age of 20 and were at least 20 years old when the pandemic began. Their outcomes were compared with siblings and randomly selected individuals from the general population matched by gender and year of birth.

The results showed that survivors of childhood cancer were less likely to contract COVID-19, possibly due to more cautious behavior. However, if they did become infected, they were 58% more likely to develop severe illness. Severe COVID-19 was defined in the study as hospitalization, admission to intensive care, or death related to the infection.

The elevated risk was especially pronounced during waves driven by highly transmissible variants like Alpha and Omicron. Differences in public health responses also played a role—Sweden’s strategy of relying on recommendations, rather than strict restrictions like those seen in Denmark, appeared to correlate with higher risks for survivors.

“Our results suggest that childhood cancer survivors should be considered a risk group in future pandemics or other health crises. This could involve prioritising them for vaccination or offering special protection during periods of high transmission,” said Javier Louro, postdoctoral researcher at the Institute of Environmental Medicine at Karolinska Institutet and first author of the study.

Reference: “COVID-19 infection and severity among childhood cancer survivors in Denmark and Sweden: a register-based cohort study”, Javier Louro, Christina-Evmorfia Kampitsi, Hanna Mogensen, Friederike Erdmann, Karin Modig, Anna Nilsson, Mats Heyman, Henrik Hasle, Anja Krøyer, Line Kenborg, Henrik Hjalgrim, Maria Feychting, Giorgio Tettamanti, The Lancet Regional Health – Europe, online July 4, 2025, doi: 10.1016/j.lanepe.2025.101363