An expert meeting convened at the National Institute of Allergy and Infectious Diseases, a division of the National Institutes of Health, in Rockville, Maryland, in 2016 to discuss the rationale and design of malaria vaccine trials in pregnant women, and a conference report was published in Vaccine. The attendees drafted a clinical development plan to test a malaria vaccine product during pregnancy using the PfSPZ vaccine being developed by Sanaria Inc. in Rockville, Maryland, that is currently in phase 2 testing as a case study.

The discussions at the meeting highlighted the recent progress in the field of maternal immunization for infectious diseases, and the evolving regulatory and ethical environment. The experts agreed that both recent progress and the new regulatory environment supported a new emphasis on testing malaria vaccines offering direct benefits in pregnant women. They stated that “initial safety and immunogenicity studies of malaria vaccines will be conducted in non-pregnant adult volunteers,” after which “efficacy trials involving pregnant women will likely be conducted in malaria-endemic and often resource-poor environments where sufficiently high malaria incidence will allow vaccine activity to be measured.”

According to meeting attendees, all such trails will need to meet all international standards and be conducted under the oversight of appropriate ethical and regulatory bodies, thereby ensuring the safety of both mothers and their children. They also noted that trials in pregnant women are known to require several special considerations, but cited trials of the influenza vaccine in pregnant women in Mali that may serve as a model for malaria vaccine trials.

Following up on the meeting recommendations, 2 post-meeting actions have been initiated. First, a pregnancy registry has been created in Ouelessebougou, Mali. The registry will provide baseline information on maternal and fetal outcomes as a context for evaluating PfSPZ vaccine safety in the future. In addition, new regimens that are suitable for evaluation in pregnant women are being tested.

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Attendees of the meeting endorsed trials for malaria vaccines in pregnant women with the condition of occurrence only when the benefits significantly outweigh the risks. They also concluded that the safety profile of the PfSPZ vaccine and the evidence of its protective efficacy warrant further consideration for and prioritization of trails in pregnant women.

Disclosures

The study authors declare that Sanaria is a for-profit company that holds relevant intellectual property (IP) and is developing PfSPZ Vaccine as a potential product.

Reference

Healy SA, Fried M, Richie T, et al. Malaria vaccine trials in pregnant women: An imperative without precedent. Vaccine. 2019;37:763-770.