Immune Response to Childhood Vaccination in Vertically Infected People Living with HIV: A Long-Term Evaluation

Despite virological suppression through antiretroviral therapy (ART), people living with HIV (PLHIV) may exhibit inadequate immune responses to vaccination, placing them at continued risk for preventable infectious diseases. Evidence regarding the durability of vaccine-induced immunity in PLHIV with vertically acquired infection remains limited.

We conducted a cross-sectional observational study to evaluate humoral immunity to routine childhood vaccines in a cohort of PLHIV with perinatally acquired infection. Antibody titers against diphtheria, tetanus, measles, mumps, rubella, varicella, and hepatitis B (HBV) were retrospectively assessed via serological testing and review of medical records. Seroprotection rates were analyzed at predefined intervals following the completion of the primary immunization schedule. Multivariate analysis was used to explore potential predictors of long-term immune response.

A total of 85 individuals were included. Two years after completing the primary vaccination series, seroprotection rates were as follows: diphtheria 71%, tetanus 79%, measles 79%, mumps 67%, rubella 87%, and varicella 54%. Five years post-vaccination, 50-70% of participants maintained protective antibody levels, declining further to 50-58% after ten years. By twenty years, protective immunity dropped below 30% for all antigens except rubella (47%). HBV vaccine responses were notably poor, with only 60%, 37%, 24%, and 7.5% retaining protective anti-HBs titers at 2, 5, 10, and 20 years post-immunization, respectively. Time elapsed since vaccination was the sole significant predictor of seroprotection across all vaccines.

In this cohort of vertically infected PLHIV, vaccine-induced immunity was suboptimal and declined markedly over time compared to the general population. These findings highlight the need for tailored immunization strategies, including timely boosters and regular serological monitoring, to maintain long-term protection in this high-risk group.