ANTIBODY RESPONSE TO VACCINATION AMONG SOUTH AFRICAN HIV-EXPOSED AND UNEXPOSED UNINFECTED INFANTS DURING THE FIRST 2 YEARS OF LIFE

Tuesday, 28th of January 2014 Print
[source]Clinical and Vaccine Immunology[|source]

Recent evidence indicates that HIV-exposed but uninfected infants (HEU) are at a higher risk of infectious morbidity and mortality than their HIV-unexposed, uninfected (HUU) peers. The underlying reason(s) for this phenomenon are still unclear but are possibly multifactorial; severity of maternal HIV disease, avoidance of breastfeeding, differences in microbial exposures, exposure to HIV itself and exposure to antiretroviral drugs for vertical transmission prevention of HIV have all been postulated. Suboptimal response to vaccination thus has been suggested to contribute to the increased infectious burden of HEU. This notion has been supported by several studies, which documented low vaccine-specific antibody titers in HIV-infected mothers and attenuated vaccine-specific antibody levels in HEU compared to HUU infants. These differences have been postulated to a) compromise transfer of maternal antibodies, b) cause differences in antibody half lives, and c) alterations in responses to vaccination

In this report, the authors established a birth cohort study in South Africa, a country with an antenatal HIV prevalence of 30%, and monitored HEU and HUU infants from 2 weeks up to 2 years of life, evaluating their vaccine-specific immune responses. Their findings and additional details are available at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3535768/

 

 Abstract

HIV-exposed but uninfected (HEU) infants born to HIV-infected mothers from areas in the world with a high burden of infectious disease suffer higher infectious morbidity and mortality than their HIV unexposed uninfected (HUU) peers. Vaccination provides protection from infection. The possibility exists that altered response to vaccination contributes to the higher rate of infection in HEU than in HUU infants. While short-term, cross-sectional studies support this notion, it is unclear whether or not HEU infants develop long-term protective immune responses following the WHO extended program on immunization (EPI). Vaccine-specific antibody responses were compared between HEU and HUU infants from 2 weeks until 2 years of age in a longitudinal South African cohort. Total IgG and antibodies specific for Bordetella pertussis, Haemophilus influenzae type b (Hib), tetanus toxoid, hepatitis B virus (HepB), and measles virus were measured at multiple time points throughout the first 2 years of life. Prevaccine antibodies (maternal antibodies passively acquired) specific for tetanus were lower in HEU than in HUU infants, while prevaccine antibodies to HepB were higher in HEU than in HUU infants. Both groups responded similarly to tetanus, Hib, and HepB vaccination. HEU demonstrated stronger pertussis vaccine responses, developing protective titers 1 year earlier than HUU patients, and maintained higher anti-tetanus titers at 24 months of age. Vaccine-induced antibodies to measles virus were similar in both groups at all time points. Our results suggest that the current EPI vaccination program as practiced in South Africa leads to the development of vaccine-specific antibody responses that are equivalent in HEU and HUU infants. However, our data also suggest that a large fraction of both HEU and HUU South African infants have antibody titers for several infectious threats that remain below the level of protection for much of their first 2 years of life

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