A promising vaccine for malaria in pregnancy

Eleven million African women were infected with malaria in 2018. The Plasmodium falciparum, the parasite that causes this disease is particularly dangerous for babies when it affects the mother during pregnancy. Thus, still in 2018, 900,000 children were born with low weight for this reason in African countries. Today, there is no vaccine to protect pregnant women from malaria (or malaria). French researchers have developed one, the first results of which are promising. The study is published in the journal Lancet Infectious Diseases. Inserm (National Institute of Health and Medical Research) claims that this vaccine, called PRIMVAC, could prevent up to 10,000 maternal deaths and 200,000 infant deaths each year.

Miscarriage, stunting, infant mortality

In the countries of sub-Saharan Africa, malaria is rife permanently. Thus, the population acquires immunity during their childhood. This is not the case for pregnant women because during pregnancy, the red blood cells infected by the parasite accumulate in the placenta. This promotes anemia, which is the lack of red blood cells, and maternal high blood pressure. The risk of miscarriage, premature delivery and stunted growth increases. With the key, a risk of infant mortality which also increases. It is important to note that women are concerned for their first pregnancy, even the second. After being infected for the first time, they acquire immunity that protects them during subsequent pregnancies.

A vaccine developed for twenty years

A team of researchers from Inserm, CNRS, and the University of Paris has been developing a vaccine for more than twenty years that could provide immunity from the first pregnancy. “This vaccine stimulates the production of antibodies which will prevent the parasite from adhering to the placenta, explains Benoît Gamain, research director at CNRS. The idea is to reproduce the immunity naturally acquired by women who have had several pregnancies. It would target young African women who have not yet had sex. ” To test the safety and efficacy of this new vaccine, a clinical trial was conducted between May 2016 and September 2017. Sixty-eight non-pregnant women aged 18 to 35 received three doses of vaccine spread over three months. Eighteen of them participated in the study at the Cochin Pasteur clinical investigation center in Paris, and the other 50 in Burkina Faso. The patients were then followed for just over a year. The researchers monitored for possible side effects and studied the immune response caused by the vaccine.

Good results after two injections

“At the three doses tested, the vaccine was well tolerated by all participants. Pain at the injection site was the main side effect, reports Benoît Gamain. In addition, we have shown that the quantity of antibodies generated by the vaccine increases after each vaccination and that these persist until 15 months after the first injection. ”. These results are encouraging, as they show an ability to trigger a lasting and potentially protective immune response against gestational malaria after only two injections. New studies, with a larger number of participants and over a longer period, will have to be carried out. “It will then be necessary to evaluate their vaccine efficacy during a first pregnancy before considering marketing”Concludes Benoît Gamain.