Exploring HIV infection and susceptibility to measles among older children and adults in Malawi: a facility-based study

Measles Seroprevalence and Vaccine Responses in Human Immunodeficiency Virus-infected Adolescents and Adults: A Systematic Review

BACKGROUND

The World Health Organization (WHO) recommends an additional dose of measles-containing vaccine (MCV) for human immunodeficiency virus (HIV)-infected children receiving highly active antiretroviral therapy following immune reconstitution. We conducted a systematic review to synthesize available evidence regarding measles seroprevalence and measles vaccine immunogenicity, efficacy, and safety in HIV-infected adolescents and adults to provide the evidence base for recommendations on the need for measles vaccination.

METHODS

We conducted searches of 8 databases through 26 September 2017. Identified studies were screened independently by 2 reviewers.

RESULTS

The search identified 30 studies meeting inclusion criteria. Across studies, measles seroprevalence among HIV-infected adolescents and adults was high (median, 92%; 27 studies), with no significant difference compared to HIV-uninfected participants (10 studies). In 6 studies that evaluated the immunogenicity of MCVs among seronegative HIV-infected adults, measles seropositivity at end of follow-up ranged from 0% to 56% (median, 39%). No severe adverse events were reported following measles vaccination in HIV-infected patients.

CONCLUSIONS

Based on similar measles seroprevalence between HIV-infected and HIV-uninfected adolescents and adults, and the low response to vaccination, these studies do not support the need for an additional dose of MCV in HIV-infected adolescents and adults. These findings support WHO guidelines that measles vaccine be administered to potentially susceptible, asymptomatic HIV-infected adults, and may be considered for those with symptomatic HIV infection if not severely immunosuppressed. Measles-susceptible adolescents and adults, regardless of HIV status, may require targeted vaccination efforts to reach critical vaccination thresholds and achieve regional elimination goals.

Safety and Immunogenicity of Measles Vaccination in HIV-Infected and HIV-Exposed Uninfected Children: A Systematic Review and Meta-Analysis

BACKGROUND

HIV-infected and HIV-exposed uninfected (HEU) children have an increased risk of measles that may be due to altered immune responses or suboptimal timing of measles vaccination. We aimed to evaluate the safety and immunogenicity of measles vaccination in HIV-infected and HEU children.

METHODS

For this systematic review and meta-analysis, we searched PubMed, Embase, Cochrane Library, CINAHL, Global Health Library and IndMED on May 9, 2018. Studies were included if they reported on safety or seroresponse (either seroprotection/seropositivity/seroconversion) after measles vaccination in HIV-infected or HEU children. We calculated pooled estimates to compare immunogenicity outcomes between HIV-infected, HEU and HIV-unexposed children, using risk ratios [RRs] (with 95%CIs). PROSPERO registration number: CRD42017057411.

FINDINGS

Seventy-one studies met the inclusion criteria (15,363 children). Twenty-eight studies reported on safety; vaccine-associated adverse events and deaths were uncommon. Sixty-two studies reported on immunogenicity, 27 were included in the meta-analysis. HIV-infected children had lower seroresponse rates after primary vaccination compared with HIV-unexposed (RR 0.74; 95%CI: 0.61-0.90, I 2  = 85.9%) and HEU children (0.78; 0.69-0.88, I 2  = 77.1%), which was mitigated by antiretroviral therapy and time interval between vaccination and serology. HEU and HIV-unexposed children had similar seroresponses. Vaccination at 6-months resulted in similar proportions of HIV-infected children having seroresponse compared with HIV-unexposed (0.96; 0.77-1.19) and HEU children (1.00; 0.73-1.37, I 2  = 63.7%).

INTERPRETATION

Primary measles vaccination at 6-months of age may provide protection against measles during early infancy in settings with high prevalence of maternal HIV-infection, however, further studies are needed to evaluate this strategy in HEU children and HIV-infected children receiving antiretroviral therapy.

FUNDING

South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation in Vaccine Preventable Diseases; Medical Research Council: Respiratory and Meningeal Pathogens Research Unit.

Maternal HIV infection associated with reduced transplacental transfer of measles antibodies and increased susceptibility to disease

BACKGROUND

Transplacental transfer of measles antibodies from mother to fetus is important in protecting against measles during early infancy. Changes in population immunity against measles in adults, including waning of immunity among HIV-infected pregnant women, could affect passive immunity acquired in utero by newborns.

OBJECTIVES

To evaluate the effect of maternal HIV infection on transplacental transfer of measles antibody in mother-newborn dyads in a setting of high maternal HIV prevalence.

STUDY DESIGN

Serum at birth was obtained from 303 mother-newborn dyads, including 196 HIV-infected and 107 HIV-uninfected women, and tested for measles IgG antibodies by ELISA. Seronegativity was defined as antibody levels <150mIU/ml and seroprotective titers as ≥330mIU/ml.

RESULTS

HIV-infected and -uninfected women had similar measles antibody titers, however, cord-blood titers were lower among HIV-exposed (788.06mIU/ml) compared to HIV- unexposed newborns (1306.6mIU/ml; p≤0.001), due to lower transplacental antibody transfer ratio in HIV-exposed (0.63) than in HIV-unexposed newborns (0.97; p≤0.001). Maternal age <25years of age was associated with lower antibody titers and lower percentage with seroprotective titer, as well as less likelihood of their newborns having seroprotective titers (70.2% vs. 86.5%; p=0.001).

CONCLUSIONS

Lower levels of measles antibody in HIV-exposed newborns and in younger women <25years old, increases the susceptibility of their newborns to developing measles. This suggest a need to re-evaluate measles immunization of women of child bearing age and the timing of measles vaccination among infants in settings with a high prevalence of maternal HIV-infection.

The re-emergency and persistence of vaccine preventable diseases

The introduction of vaccination worldwide dramatically reduced the incidence of pathogenic bacterial and viral diseases. Despite the highly successful vaccination strategies, the number of cases among vaccine preventable diseases has increased in the last decade and several of those diseases are still endemic in different countries. Here we discuss some epidemiological aspects and possible arguments that may explain why ancient diseases such as, measles, polio, pertussis, diphtheria and tuberculosis are still with us.