Innovative vaccine demonstrates sustained malaria immunisation in pregnancy

Two trials (Phase I and Phase II) of a vaccine given to healthy adults from Mali has demonstrated its potential as a safe and effective way to immunise against malaria, prior to and during pregnancy.

In one trial, the PfSPZ vaccine was evaluated in 300 healthy women ages 18 to 38 years. These individuals hoped to become pregnant soon after being vaccinated.

Participants in the trial first were administered with a drug to remove malaria parasites, then given three injections, at one of two doses, over a one-month period. The treatment regimens involved the vaccine or a placebo, the researchers confirmed.

A ‘first’ for a malaria vaccine

Based on the findings, both dosages enabled participants to be protected over two years without requiring a booster dose. They highlighted that this is a first for any malaria vaccine.

An exploratory analysis also revealed that women who conceived during the study, were significantly protected from malaria during pregnancy, the researchers stated.

There were 55 women who became pregnant within 24 weeks of the third dose. For individuals who received a lower dose against parasitemia, efficacy was reported to be 65 percent. This was 86 percent in those given the higher dose of the vaccine.

Of the 155 women who became pregnant across the two study years, vaccine efficacy was 57 percent for the lower dose and 49 percent who were administered with the higher dose.

The researchers noted that the parasitemia risk for participants during the periconception period was reduced by 65 to 86 percent with the PfSPZ vaccine. They speculated that PfSPZ could prevent malaria-related early pregnancy losses.

Potential of the investigational immunisation agent

“Preconception immunisation is a new strategy to reduce mortality for women with malaria in pregnancy,” the researchers explained. “Existing measures are not protecting women from malaria in pregnancy,” they added. “A safe and effective vaccine is urgently needed, and our results indicate PfSPZ vaccine might be a suitable candidate,” they added. 

The team remarked that they plan to evaluate the safety of PfSPZ given during pregnancy. They will then assess the efficacy of PfSPZ administered prior to conception or during pregnancy in larger clinical trials.

Results from the Phase I and Phase II trials were published inThe Lancet Infectious Diseases. 

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