[Response to hepatitis b vaccination in at-risk group patients].

OBJECTIVE: It is known that between 5-10% of individuals vaccinated against hepatitis B virus (HBV) do not develop protective antibody levels. Several factors negatively influence the immune response. The aim of this paper was to evaluate the immunological response to HBV vaccination in at-risk populations and analyze its variation according to the type of vaccination schedule (primary vaccination or booster dose), age, sex, and risk group. METHODS: A longitudinal descriptive study was conducted on patients between 04/11/2021-15/06/2023 at the Preventive Medicine vaccination clinic at Hospital Infanta Leonor (Madrid, Spain). Patients from risk groups who had completed a full vaccination schedule (high-dose or adjuvant vaccine) or received a booster dose were included. Criteria for exclusion were incomplete vaccination schedules and absence of post-vaccination serology. A non-probabilistic convenience sampling was used, including all available patients who met the inclusion criteria. The sample size was 77 patients. Variables considered were: age, sex, risk pathology, and HBsAbs levels at 1 to 2 months post-vaccination. The immune response (HBsAbs ≥10 mUI/ml) was analyzed according to the collected variables using chi-square and logistic regression. RESULTS: Out of 572 patients that were assessed, 97 had received vaccination. Serology data was available for 77 patients: primary vaccination (n=51), booster dose (n=24), and revaccination (n=2). Mean age was 43.7 (15.7) years, 76.6% were men. Distribution by risk group was: 59.7% HIV, 28.6% immunosuppression, 11.7% chronic kidney disease. Among the 77 patients included in the study, 87% (95% CI: 77.4-93.6) responded to vaccination, with differences in response evident in the age ranges: 96.8% (95% CI: 83.3-99.9) of those under fourty years of age responded adequately compared to 50% (95% CI: 18.7-81.3) of those over fifty-five years (p=0.002). In the primary vaccinated group, those patients that were over fifty-five years of age had a 96% lower probability of mounting an adequate immune response compared to those under fourty years, adjusted for other variables (OR=0.04, 95%CI: 0.002; 0.70) (p=0.028). CONCLUSIONS: Most individuals vaccinated against HBV show an adequate immune response, although older age is associated with a reduction in response to the vaccination. Maintaining complete and updated vaccination schedules is essential, especially in older patients, to ensure effective protection.