Background
Despite successful antiretroviral therapy (ART), people living with HIV (PLHIV) are at risk of suboptimal vaccine response, exposing this vulnerable population to common vaccine-preventable diseases.
Methods
This cross-sectional observational study evaluated humoral responses to vaccination in a cohort of PLHIV with vertically acquired infection. Seroprotection rates for diphtheria, tetanus, measles, mumps, rubella, varicella, and hepatitis B (HBV) were assessed at predefined intervals following primary immunization and at the most recent follow-up visit up to October 31, 2023, through a review of serological analyses and available medical records. Associations between vaccine responses and predictive factors were examined.
Results
Eighty-five vertically infected PLHIV were included in the study, with a median age of 24 years(IQR 16–31 years). Before starting ART, 38% were at CDC stage 1, 24% at stage 2, and 38% at stage 3. In 2023, these percentages were 36%, 24%, and 40%, respectively. Only 27% began ART within their first year of life, with a median age of 53 months at initiation (IQR 12–118 months). By 2023, all patients were on ART, with 92% achieving undetectable viral loads. Two years after the last vaccine dose, seroprotection rates were 71% for diphtheria, 79% for tetanus and measles, 67% for mumps, 87% for rubella, and 54% for varicella. After five years, 50-70% retained protective antibodies, dropping to 50-58% after ten years, and below 30% after twenty years for most vaccines, except rubella (47%). Protection rates for HBV were the lowest, with only 60%, 37%, 24%, and 7.5% retaining protection after 2, 5, 10, and 20 years (Figure 1). In 2023, considering the most recent serologies available, seroprotection rates among PLHIV were 37% for diphtheria, 61% for tetanus, 46% for measles, and 25% for HBV. On multivariate analysis comparing seroprotected with non-seroprotected PLHIV (considering factors such as starting ART before 12 months of age, current CDC stage 3, CD4 count at the last vaccination dose, years since the last vaccination dose, complete vaccination schedule, and sex), only the years since the last vaccination dose correlated with vaccine response for all vaccinations.
Conclusions
In this cohort of vertically infected PLHIV, seroprotection following vaccinations was lower and less durable compared to the general population. Thus, strict adherence to vaccination schedules and regular serological monitoring are essential for effective management of this population.
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