Breakthrough malaria vaccine offers long-term protection for pregnant women

Sanaria Inc.Aug 14 2024

In a report published in The Lancet Infectious Diseases (Safety and efficacy of PfSPZ Vaccine against malaria in healthy adults and women anticipating pregnancy in Mali: two randomized, double-blind, placebo-controlled, phase 1 and 2 trials) a team led by investigators at the Malaria Research and Training Center (MRTC), Bamako, Mali; the Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases, National Institutes of Health; and Sanaria Inc. describes the durable protective efficacy against malaria shown by Sanaria^® PfSPZ Vaccine when administered to women prior to pregnancy. The two clinical trials, led by Dr. Halimatou Diawara (MRTC) and Dr. Sara Healy (LMIV), were conducted in Ouélessébougou, Mali from 2018-2021. For the first time, immunization with a malaria vaccine has been shown to protect mothers from malaria during pregnancy and to protect for two transmission seasons without booster doses of vaccine.

Malaria during pregnancy is an enormous problem. Plasmodium falciparum (Pf) infection during pregnancy causes up to an estimated 50,000 maternal deaths and 200,000 stillbirths in Africa each year.

Better protection for the mother and developing fetus is urgently needed. PfSPZ Vaccine has an excellent safety profile and our teams have worked with NIH and Sanaria partners over the years to demonstrate its efficacy in Mali, where seasonal malaria transmission is intense."

Professor Abdoulaye Djimde, Director of the Malaria Research and Training Center at University of Bamako

This trial recruited women who were planning to get pregnant in the coming year. After immunization, birth control was stopped in most and the women were followed through two malaria transmission seasons over nearly two years. Those who became pregnant were followed throughout their pregnancies, and newborns were followed up to their first birthday to measure long-term outcomes. The study included two vaccine groups that received low and high doses of the vaccine, respectively (100 women per group) and a placebo group receiving normal saline (also 100 women).

PfSPZ Vaccine was well-tolerated and safe for both the mothers and their offspring, with no differences evident in the rate or severity of adverse events compared to placebo. Vaccine efficacy against infection with malaria parasites in the lower dose group was as high or higher during the second year (61%) as during the first year, without boosting, a first for a malaria vaccine. Over the two seasons, efficacy against infection with malaria parasites during pregnancy was 57% in this group. In the high dose group, efficacy against malaria infection was 86% during the first year in women who became pregnant.

An unexpected finding was that pregnancy was detected earlier in the vaccine group than placebo. Although this effect had marginal statistical significance, it suggested that malaria infection likely aborts many early pregnancies before they are detected. By preventing these early infections, vaccinated women appeared to become pregnant sooner. This was actually noticed by several of the mothers: "The vaccine, I love it" said one participant; "since the start of the study I have not had malaria." Another participant stated: "I was unable to conceive for three years after getting married, but during the study I got pregnant".

Alassane Dicko, who leads the team in Mali, said that assessing the efficacy of PfSPZ Vaccine in women who wanted to become pregnant was the next logical and ethical step. "We were excited to see significant vaccine efficacy against Pf infection not only in the first year but through a second intense malaria transmission when administered pre-conception. This is a tremendous advance for protecting women against malaria before and during pregnancy. We were also surprised to find an additional positive outcome, that pregnancies developed sooner in vaccinated participants."

Sanaria founder and CEO, Stephen L. Hoffman, MD said, "Sanaria's PfSPZ Vaccine has a long and excellent safety and tolerability record, and has shown strong and durable protection against Pf infection in multiple studies in Africa. The results of this study in women of child-bearing potential demonstrate clearly its potential to save the lives of women and their unborn babies in Africa." Hoffman believes the vaccine will be best administered to adolescent girls prior to any pregnancies, who would then get boosted at the time of pregnancy. A full immunization series would be given to any pregnant women not previously immunized. The next step will be to demonstrate the safety and efficacy of PfSPZ Vaccine in pregnant women.

"While pregnant women are typically excluded from many clinical studies, given the scale of the problem and the profound effects of malaria on women of child-bearing potential, there is an ethical imperative to design and test interventions for this vulnerable group" said Rose Leke, Profesor, University of Cameroon, winner of the 2023 Virchow Prize for Global Health, and chair of the Gavi (Global Alliance for Vaccines and Immunizations) independent review committee. " I applaud this research team for successfully pioneering the safe testing of PfSPZ Vaccine in young women and achieving such promising results on preventing malaria in pregnancy."