Vaccine Confidence in Pregnant Women Living With HIV Requires Further Study

Limited data exist on the safety and efficacy of vaccines for pregnant women living with HIV (PWLWH), which can lead to difficult policy decisions for this population, according to a review published in eClinicalMedicine. PWLWH should be the focus of studies in the future, the authors conclude.

Mother-to-child transmission of HIV has been largely eliminated due to the usage of combined antiretroviral therapy (cART). The estimated 5.4 million children worldwide who are HIV-exposed but uninfected (HEU) often have vulnerability to other infections. Vaccine trials often do not include pregnant women, especially PWLWH who could benefit from the vaccines to protect their infants. This study aimed to assess the safety and efficacy of vaccines that were given to PWLWH that could reduce the morbidity and mortality of HEU.

Pregnant woman | Image credit: pressmaster - stock.adobe.com

MEDLINE, Embase, Web of Science, Virtual Health Library, and Cochrane Library were used to search for studies that involved the safety and efficacy of vaccines given to PWLWH. The search specifically looked for randomized controlled trials and observational studies that took place between the inception of the database and September 6, 2023. Studies were eligible if the study included a vaccine being given to a PWLWH during their pregnancy with a controlled group of women who were not living with HIV. Studies were excluded if they were review articles, a case series, conference abstracts, letters, or animal studies.

Data extracted from the studies included the HIV status of the mother, treatment they received, gestational age at the time of vaccine distribution, and the formulation of the vaccination that was given.

There were 12 studies included in the final analysis which included 3744 pregnant women, of which 1714 were PWLWH. The studies came from South Africa, Brazil, and Malawi. Pneumococcal, influenza, and group B streptococcus vaccines were tested in this population.

There were 5 studies that reported on the safety of the vaccines in 3456 pregnant women, of which 1250 were PWLWH. A total of 4.1% of PWLWH reported at least 1 severe local reaction and 18.6% reported at least 1 severe systemic reaction in 1 of the studies. This is compared with pregnant women without HIV, who reported at least 1 severe local reaction in 5% of cases and at least 1 severe systematic reaction in 15% of cases. An increased rate of injection site reactions were reported in a separate study. The most common severe adverse event was preterm births, which occurred in 17% of PWLWH compared with 10% of pregnant women without HIV.

Antibodies in PWLWH from vaccines were found to be lower compared with pregnant women without HIV after 4 weeks, even though the antibodies increased in PWLWH from baseline. The pooled mean difference in the concentration of antibodies from before the vaccination to 28 to 35 days after found that there was an increase in the concentration of antibodies in the 3 studies that did the analysis. However, when comparing PWLWH to pregnant women without HIV, the latter were found to have significantly higher antibody concentration compared with PWLWH (mean difference, –141.8; 95% CI, –194.9 to –88.6).

There were some limitations to this study. The PWLWH who were included in this study make up a small percentage of the overall population of PWLWH. The methodological quality of the studies was important to the findings. The results of only 3 studies were able to be pooled for the meta-analysis. None of the studies used in the review used the Global Alignment of immunization criteria to measure the safety of vaccines.

The researchers concluded that more data on vaccine safety in pregnant women is necessary for any new vaccines coming to the market. “The availability of uniform accurate data and standardized definitions will improve maternal vaccine confidence especially in special sub-populations such as PWLWH who may require different vaccine formulations or schedules to keep themselves and their infants protected,” the authors wrote.

Reference

Nakabembe E, Cooper J, Amaral K, et al. The safety and immunogenicity of vaccines administered to pregnant women living with HIV: a systematic review and meta-analysis. eClinicalMedicine. 2024;69:102448. doi:10.1016/j.eclinm.2024.102448