Vaccines safe for pregnant women with HIV but show reduced immune response

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In a recent study published in the journal Dr eClinical MedicineResearchers conducted a meta-analysis on the immunogenicity and safety of vaccines for pregnant women living with human immunodeficiency virus (HIV) infection (PWLWH), comparing their immunogenicity effects with those without HIV infection (PWH).

Increased access to lifelong combination antiretroviral therapy (cART) has contributed significantly to the global reduction in mother-to-child HIV transmission. HIV-infected uninfected (HEU) children have a higher burden of infectious diseases than HIV-unexposed and uninfected (HEU). Immunization of PWLWH individuals can reduce the severity of infectious diseases in early childhood. However, previous reports indicate that maternal vaccines given to PWLWH may be less immunogenic than vaccines given to PWH. Most HEU children live in low- and middle-income countries, especially SSA, where the burden of HIV is highest. The World Health Organization (WHO) recommends tetanus vaccine for pregnancy, and evidence from clinical trials supports the safety and immunogenicity of other maternal vaccines. However, data on safety and immunogenicity in pregnant women are scarce.

Study: Safety and immunogenicity of vaccines administered to pregnant women living with HIV: a systematic review and meta-analysis.  Image Credit: Hit Stop Media/ShutterstockStudy: Safety and immunogenicity of vaccines administered to pregnant women living with HIV: a systematic review and meta-analysis.. Image credit: Hit Stop Media/Shutterstock

About the study

In the current meta-analysis, researchers examined the immunogenicity and safety of vaccines for pregnant women exposed to HIV.

The team searched the Embase, Medline, Web of Science, Cochrane, and Virtual Health Library databases from study initiation on January 31, 2022, and re-searched between February 1, 2022, and September 6, 2023, without language restrictions. Additionally, they searched relevant research references to identify additional records.

The study included observational studies and randomized clinical trials administering the vaccine to women living with HIV infection and a comparison group of HIV-uninfected women. They exclude animal studies, reviews, conference abstracts, and case series. Two researchers independently screened titles and abstracts, and a third researcher resolved disagreements.

Researchers followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for analysis. They used the Newcastle-Ottawa Scale (NOS) to assess the methodological quality of non-randomized controlled trials. Three researchers assessed risks of bias related to randomization sequence generation, allocation concealment, blinding of personnel and participants, blinding of outcome assessment, selective reporting, and insufficient outcome data. They assessed publication bias based on the asymmetry of funnel plots.

The team performed random effects modeling for the meta-analysis, calculating effect sizes using the inverse variance-weighted method by evaluating geometric mean titers (GMT) and reporting them as mean differences. They used the I2 statistic to assess heterogeneity across studies. They performed group-level analyzes including HIV status and vaccine subtype.


The initial data search yielded 96,160 records, of which 75 underwent full-text screening, and 12 were eligible for meta-analysis, including 3,744 expectant women, of whom 1,714 were PWLWH. They identified three vaccines in the study, namely for group B streptococci (GBS), influenza virus and pneumococci. They rated the overall risk of bias as low, but the outcome assessment identified blinding-related bias as clear.

Five studies, including 3,456 PWLWH women, reported safety outcomes with no increase in reported adverse events in PWLWH compared with non-PWLWH. The increase in GMT at weeks 28–35 from baseline ranged from 12 to 239 in HA units. The pooled geometric mean difference in hemagglutination inhibition (HAI) titers after influenza vaccination was 56. The increase was lower in PWLWH than in PWLWH: −142. The team observed the most significant difference in women receiving the B strain (−166) and the least significant difference (−112) in women receiving the A/H3N1 vaccine.

One study documented one or more serious local reactions in four percent of PWLWH, whereas 19% had one or more serious systemic reactions in the week after vaccination. Compared to PWWH, five percent reported one or more serious local reactions, and 15% reported one or more serious systemic reactions. One study documented an increased frequency of injection-site adverse reactions with double-dose influenza vaccination in women living with HIV infection. The most frequent serious adverse event was preterm delivery, with a higher rate among HIV-infected expectant mothers than their HIV-uninfected counterparts.

In five studies evaluating immunogenicity for pneumococcal, influenza, and GBS vaccines, all reported elevated antibody titers after four weeks of vaccination among PWLWH compared with baseline; However, antibody titers were lower in PWWH than in PWWH. Three influenza vaccine studies had sufficient comparative data for meta-analytic studies stratified by vaccine subtype (A/H1N1 virus, A/H3N2 virus, B/Victoria virus, and B/Yamagata virus). The mean difference in antibody titers 28 to 35 days after influenza vaccination was significantly higher in PWLWH than in PWWH.

Overall, the results of the study showed that there are limited data on the immunogenicity and safety of vaccines administered to HIV-infected expectant mothers. There was no difference in vaccine safety between PWLWH and PWH for influenza, pneumococcal, and investigational GBS vaccines, but there was a significant elevation of antibody titers four weeks after vaccination; However, increases were lower in PWLWH than in PWWH. The findings emphasize the potential challenges of vaccine policy in countries with high HIV burden and the need for inclusion of PWLWH in maternal vaccine trials to promote vaccine confidence.

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