Vaccination coverage and serological follow-up in children with rheumatologic diseases: a retrospective single-centre study

BACKGROUND: Children with rheumatologic diseases often require immunosuppressive therapies, which can compromise their immune response and increase susceptibility to infections. Despite the heightened risk, vaccination coverage in this population is frequently suboptimal, largely due to concerns over vaccine safety, especially live attenuated vaccines, and the absence of clear, universally adopted guidelines. OBJECTIVE: This retrospective study aims to evaluate the vaccination status and serological immunity of pediatric patients with rheumatologic diseases at the time of diagnosis, prior to initiation of immunosuppressive therapy. METHODS: We conducted a retrospective review of medical records from children under 16 years of age diagnosed with a rheumatologic disease at Geneva University Hospitals (HUG) between 2005 and 2023. Demographic data, clinical diagnosis, vaccination history, and available vaccine-specific serologies were collected and analysed. RESULTS: Seventy-four patients were included, with a median age at diagnosis of 6 years. At the time of diagnosis, vaccination coverage was highest for Haemophilus influenzae type b (Hib; 93%), followed by diphtheria and tetanus (91%), measles-mumps-rubella (MMR; 80%), pertussis and poliomyelitis (77-78%), pneumococcus (77%), varicella-zoster virus (VZV; 72%), and hepatitis B virus (HBV; 64%). Baseline serological testing was available in only half of the patients (38/74, 51%). Among those tested, seroprotection was highest for Hib (100%), followed by tetanus (91%), measles (89%), diphtheria (88%), hepatitis B (58%), varicella (47%), and pneumococcus (42%). Longitudinal follow-up revealed limited and inconsistent serological monitoring, with only a minority of patients undergoing repeat testing, and very few receiving booster vaccinations, despite the generally stable protection levels observed over time. CONCLUSIONS: Vaccination coverage in children with rheumatologic diseases remains suboptimal, particularly for varicella, hepatitis B, and pneumococcus. These findings underscore the critical importance of optimizing vaccination coverage at diagnosis and establishing systematic serologic surveillance protocols in this high-risk population, rather than relying solely on vaccine history.