Impact of HIV on Measles and Measles Immunisation
Condition: HIV Infection; Measles; Children
MeSH terms: Measles
Study type: Observational

Summary: 
      We conducted a longitudinal study to assess the immunogenicity of standard-titer measles
      vaccine in HIV-infected and uninfected Zambian children. The study hypothesis was that
      HIV-infected children would have higher rates of primary and secondary measles vaccine
      failure compared to uninfected children, contributing to decreased levels of population
      immunity to measles and facilitating measles virus transmission in regions of high HIV
      prevalence.
    

Detailed description: 
      Despite great progress in measles control in sub-Saharan Africa, measles remains a
      significant cause of morbidity and mortality in young children. In regions of high HIV
      prevalence, measles virus transmission may be sustained despite high immunization coverage
      rates if HIV-infected children are important transmitters of measles virus. Factors
      potentially contributing to enhanced measles virus transmission by HIV-infected children
      include an early decline in protective maternal antibody titers resulting in susceptibility
      to measles at a younger age, and high rates of primary and secondary measles vaccine failure.
      To evaluate the potential impact of the HIV-1 epidemic on immunity following measles
      vaccination, we conducted a longitudinal study to compare the primary vaccine failure rate
      and rate of antibody decline following administration of standard-titer measles vaccine at
      nine months of age to HIV-infected and HIV-uninfected Zambian children. Our results show that
      children born to HIV-infected women have lower levels of passively-acquired maternal
      antibodies to measles virus prior to the age of routine vaccination at 9 months, and
      HIV-infected children are particularly susceptible to measles in infancy. This finding
      supports the WHO recommendation to provide the first dose of measles vaccine to HIV-infected
      children at 6 months. Furthermore, HIV-infected children develop adequate primary antibody
      responses to measles vaccine in the months following vaccination but lose protective antibody
      titers by two to three years of age. Mitigating the potential impact of this decreased
      immunogenicity on the level of population immunity to measles virus was the high mortality
      rate observed among HIV-infected children. Improved access to antiretroviral therapy will
      likely improve the survival of HIV-infected children without enhancing protective immunity to
      measles virus, although this has yet to be investigated. We are working to incorporate our
      findings into a mathematical model to better understand the impact of the HIV-1 epidemic on
      measles control strategies and to investigate the immunologic mechanisms for impaired memory
      B cell responses in HIV-infected children.
    

Intervention name(s): standard-titer measles vaccine
Intervention type(s): Biological
Observational model: Defined Population
Time perspective: Prospective
Keywords: HIV; measles; measles vaccine; children; Zambia