Adult survivors of childhood cancer were 58% more likely to develop severe COVID-19 compared to the general population, despite being less likely to contract the virus, according to a recent study.
Vaccination coverage was higher among survivors (90.3%) compared with controls (88.8%). Despite this, the elevated risk of severe disease suggests a persistent vulnerability possibly related to long-term effects of cancer treatment, noted researchers.
A nationwide register-based cohort study was conducted in Denmark and Sweden to assess the risk of COVID-19 infection and severe disease among adult survivors of childhood cancer. The study, led by Javier Louro ofKarolinska Institutet, Stockholm, leveraged comprehensive registry data from both countries. The study population included 13,659 childhood cancer survivors, 58,803 matched individuals from the general population, and 17,531 siblings.
Eligible participants were diagnosed with cancer before age 20 and were at least 20 years old on January 1, 2020. Follow-up extended through December 31, 2022. COVID-19 outcomes were derived from national registries: severe COVID-19 was defined as hospitalization, intensive care admission, or death where COVID-19 was the primary or a contributing diagnosis. Registered infection included PCR-confirmed test results or clinically documented COVID-19 diagnoses. Researchers employed Cox proportional hazards models to estimate adjusted hazard ratios (aHRs), accounting for demographic characteristics, comorbidities, educational level, vaccination status, and history of malignancy after age 20.
The analysis demonstrated that childhood cancer survivors had a 58% increased risk of developing severe COVID-19 compared to matched population controls, despite a 9% lower likelihood of being diagnosed with a COVID-19 infection. The risk of severe outcomes was notably higher among survivors aged 50 years or older (aHR = 1.85), those diagnosed with cancer at ages 15 to 19 (aHR = 2.28), and survivors with a history of solid tumors (aHR = 1.63). The disparity widened during the second half of the pandemic, particularly between July 2021 and December 2022, when the risk more than doubled among survivors (aHR = 2.35), and was most pronounced in Sweden (aHR = 2.89).
"These findings highlight the heightened vulnerability of childhood cancer survivors and emphasize the need to consider this group as at higher risk, proposing tailored interventions to safeguard this population during future health crises," concluded Louro and colleagues.
They reported no conflicts of interest.