Seroprevalence of Measles Antibody Among HIV-Exposed and HIV-Infected Indian Children: An Unmatched Case Control Study

Background: HIV-infected children (CLHIV) are known to have impaired seroconversion or waning immunity following seroconversion against measles. This may result in measles infection, morbidity and mortality among CLHIV and is also a challenge to measles elimination. Objectives: To compare measles seroprevalence between vaccinated CLHIV and HIV-exposed uninfected children (HEU). The null hypothesis (H₀) was that the difference in proportions for measles seroconversion between CLHIV and HEU is not statistically significant. Materials and Methods: An unmatched case-control study was conducted among 35 CLHIV and 28 HEU aged 18 months to 8 years, attending the Paediatric Centre of Excellence in HIV care (PCOE) at Medical College, Kolkata, between 2022-2024. Participants provided demographic and treatment details; venous blood sample was collected and tested using an ELISA kit to detect measles IgG. We measured outcome as distribution of measles IgG titre and odds ratio (OR) for seroconversion with 95% confidence interval (CI). Results: Groups were similar by sex, weight and duration since last measles vaccine, but differed in age. There were 50% of HEU and 33.7% of CLHIV who had seroconverted, with Measles IgG antibody ≥ 275 IU/L. The overall seroconversion rate was 41%; the difference in proportion did not reachstatistical significance (χ² = 1.7; p = 0.18). However, antibody distributions according to serostatus were significantly different by the Mann-Whitney U test (p = 0.04).Conclusion: Null hypothesis could not be rejected; a combination of vaccine failures and waning immunity possibly resulted in low seroconversion. This indicates existing pockets of vulnerability which could hinder measles elimination.