Measles and rubella seroprevalence among HIV-infected and uninfected Zambian youth

Background: Measles and congenital rubella syndrome remain significant causes of morbidity and mortality despite available vaccines. HIV-infected youth may be at increased risk of measles because of greater waning immunity after vaccination. At a population level, they constitute a potentially large pool of susceptibles to measles and rubella. More data among HIV-infected youth in sub-Saharan Africa are needed to guide vaccination policy and control strategies. Methods: This cross-sectional study was nested within 2 ongoing studies of malaria and HIV in Zambia. Dried blood spot cards from youth (5-15 years) in these studies from 2009 to 2013 were tested for IgG antibodies to measles and rubella viruses. HIV-uninfected youth, HIV-infected treatment-naive youth and HIV-infected youth receiving antiretroviral therapy (ART) were compared. Results: A total of 617 HIV-uninfected, 144 HIV-infected treatment-naive and 128 HIV-infected youth receiving ART were included in this study. The proportion seropositive for measles virus was significantly higher among HIV-uninfected youth (92.5%) compared with HIV-infected treatment-naive youth (74.1%) and HIV-infected youth receiving ART (71.9%). No differences by age were observed. The proportion seropositive for rubella virus was significantly higher among HIV-uninfected youth (54.7%) compared with HIV-infected treatment-naive youth (41.7%) and HIV-infected youth receiving ART (49.6%), with increases observed by age for all groups. Conclusions: Measles seroprevalence was lower among HIV-infected than uninfected youth, consistent with waning immunity after measles vaccination. HIV-infected youth would benefit from revaccination. Half of all youth in rural Zambia were susceptible to rubella and may need targeting for catch-up rubella campaigns when measles-rubella vaccine is introduced.