Vaccine offers hope for malaria prevention in pregnancy

Vaccine offers hope for malaria prevention in pregnancy

Malaria in pregnancy is still a major concern for the health sector due to the detrimental effects it has on infected mothers and their unborn children.

In malaria-endemic areas or hotspots, people acquire immunity throughout their childhood. This means that they are generally protected against its most severe outcomes once they reach adulthood.

However, pregnant women are an exception. When they get malaria, their red blood cells — infected with plasmodium falciparum parasites that cause the disease — usually accumulate in the placenta hence promoting anaemia and gestational hypertension, which are life-threatening.

The disease is also linked to a higher risk of spontaneous abortion, premature birth and growth delays of the unborn child, which lead to low birth weight and a high rate of child mortality or deaths.

To avert these complications, the World Health Organisation recommends that pregnant women sleep under insecticide-treated bed nets, take preventive drugs and get prompt treatment when infected.

But due to low awareness or ignorance of this preventive measure, malaria in pregnancy is still a major cause of maternal and child mortality in Kenya and other sub-Saharan African countries.

Worse still, the growing problem of insecticide resistance is increasingly compromising the effectiveness of bed nets for malaria control.

In a bid to seek a long-term solution to the challenge, scientists have been burning the midnight oil to find ways of developing a vaccine that is ideal for preventing malaria in pregnancy.

For the past two decades, a team of researchers from the French National Institute of Health and Medical Research (Inserm), as well as the University of Paris have been developing a vaccine for pregnancy malaria.

The goal of the candidate vaccine, known as PRIMVAC is to prevent the deaths of thousands of mothers and babies caused by the condition each year.

“Developing an effective vaccine for young women before their first pregnancy is a priority if we are to reduce malaria-related deaths,” stated Dr Benoît Gamain, the lead author of the study and director of the French National Centre for Scientific Research (CNRS).

He stated: “An effective strategy could focus on a population similar to that targeted by HPV vaccination, for example, before the women become sexually active.”

New findings published in The Lancet Infectious Disease Journal indicate that the vaccine is safe and effective for the prevention of malaria in pregnancy.

The study marked the first human trials of the candidate vaccine. But it did not evaluate the placental vaccine in pregnant women.

The results show that PRIMVAC can induce an appropriate immune response, up to 15 months after the initial vaccination.

It was evaluated in 68 non-pregnant women aged between 18 and 35 at the Cochin Pasteur Clinical Investigation Centre in Paris, then at the National Centre for Research and Training on Malaria in Ouagadougou, Burkina Faso.

The participants were randomly assigned to four groups. They received the vaccine at various doses on three occasions for three months.

These women were then monitored for 15 months to identify and treat any side effects. During this period, the researchers also studied the immune response induced by the vaccination among the women.

The results of this study indicated that PRIMVAC is well-tolerated. It also showed that the vaccine could produce an immune response.

Indeed, the production of antibodies happened in all women vaccinated after only two injections.

Most importantly, the study revealed that the antibodies produced by the vaccine are capable of both recognising the parasites on the surface of the infected red blood cells and inhibiting their adhesive capacity, which is responsible for their accumulation in the placenta of pregnant women.

“We were able to show that the vaccine is well-tolerated, at all the tested doses. The side effects observed were mainly pain at the injection site,” stated Dr Gamain.

“We also revealed that the quantity of antibodies generated by the vaccine increases after each vaccination and that they persist for several months. It, therefore, appears that the vaccine can trigger a lasting and potentially protective immune response.

With these promising results, the researchers want to continue monitoring the volunteers in Burkina Faso to evaluate whether the immune response induced by the vaccination is maintained until their first pregnancy.

The success of the vaccine will be a major public milestone that will boost maternal and child health outcomes in malaria hotspots across Kenya and Africa.

According to the 2019 Kenya Economic Survey, 4,675,362 malaria cases were confirmed in public health facilities in the past year alone.

Credit: Business Daily Africa