Immunogenicity and Safety of an Early Measles Vaccination Schedule at 6 and 12 Months of Age in Human Immunodeficiency Virus (HIV)–Unexposed and HIV-Exposed, Uninfected South African Children

Abstract

Background Measles morbidity and mortality rates are greatest in children <12 months old, with increased susceptibility in human immunodeficiency virus (HIV)–exposed children. We evaluated the immunogenicity and safety of an early 2-dose measles vaccine regimen administered at 6 and 12 months of age in South Africa. Methods HIV-unexposed (HU) (n = 212) and HIV-exposed, uninfected (HEU) (n = 71) children received measles vaccination (CAM-70) at 6 and 12 months of age. Measles immunoglobulin G titers were measured by means of enzyme-linked immunosorbent assay before and 1 month after each vaccine dose. Results The majority of children (88.2% HU and 95.8% HEU; P = .04) were seronegative (<150 mIU/mL) to measles at 4.2 months of age. This was particularly evident among infants of mothers born from 1992 onwards (year of public nationwide measles vaccine availability). One month after the first measles vaccine, 42.3% of HU and 46.4% of HEU children were seropositive (≥330 mIU/mL). After the second dose, the proportion seropositive increased to 99.0% in HU and 95.3% in HEU children. Safety profiles were similar between HU and HEU children. Conclusions Early 2-dose measles vaccination at 6 and 12 months of age was safe and induced antibody responses in HU and HEU children, which could partly offset the early loss of maternally derived antibodies in infants born to predominantly measles-vaccinated mothers. Clinical Trials Registration NCT03330171

Insufficient measles antibody protection in 6‐month‐old Malawian infants: Reconsider vaccination schedule?

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“…The current measles vaccine policy seeks to optimise seroconversion rates since an early vaccination can lead to blunted antibody responses and lower IgG levels later in life; however, evidence from randomised studies in low-income countries [29][30][31][32] suggests that an earlier MV, in the presence of maternal antibodies, could reduce all-cause mortality, both providing infant protection from measles infection and conferring beneficial non-specific effects against non-measles infections. In light of these results, the vaccine strategy could be reconsidered, but at present, only a few countries, including South Africa, have anticipated to 6 months of age the MV [17].…”

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“…Even if MMR vaccines cannot be administered to severely immunocompromised persons, human immunodeficiency virus (HIV)-infected children with a CD4 T-cell count above severe immunosuppression thresholds and asymptomatic HIVinfected children could receive MMR vaccination according to routine childhood schedules [84][85][86]. Two doses of measlescontaining vaccine administered at 6 and 12 months of age were shown to be similarly safe and immunogenic in HIVunexposed and HIV-exposed, uninfected children [87]. However, HIV-infected children and adolescents may need additional MMR vaccine doses to achieve sufficient levels of immunity, especially if antiretroviral therapy has been interrupted [88].…”

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