Could Latest Vaccine Trials Promise End to Infant Malaria Mortality?

Vaccine improvements are “bringing us closer to a malaria-free world,” say scientists working on a trial across Sub-Saharan Africa. 

The newly engineered R21 vaccine, developed by Oxford University and Serum Institute of India Pvt Ltd, has shown the highest protection rates ever in young children according to a paper published this month in the Lancet.

The trial, involving 4800 children, found the vaccine reduced the number of malaria cases by 78% in children aged 5-17 months, making it the first to surpass the WHO threshold of 75%.

Africa has the highest number of Malaria cases in the world accounting for 94% of the 249 million cases recorded worldwide in 2022. While people of all ages can catch the disease, deaths are disproportionately made up of children and pregnant women.

The ongoing trial is taking place at six sites across Burkina Faso, Kenya, Mali and Tanzania which suffer from either seasonal or year-round malaria. The recent phase 3 results suggest that R21 could provide a safe, effective and affordable way to combat the disease across the continent.

The lead investigator in Mali, Professor Alassane Dicko, said he believes the vaccine “should be very impactful in preventing malaria deaths in African children.”

While the trial shows promising data, the researchers noted that the initial high protection rate falls to around 60% after 12 months. They also found that the vaccine was less effective in sites where malaria was present year-round rather than seasonally. This is likely a consequence of the vaccine becoming less effective over time, while contraction risks remain consistent.

Dr Alena Pance, a Senior Lecturer in Genetics at the University of Hertfordshire said, “the data shows a slightly lower efficacy in regions with continuous malaria transmission and there is a tendency to weaning off the effect at the 12-month period, which is a bit concerning.”

Another concern is that the vaccine was mostly effective in children up to 17 months old. For those aged 18 to 36 months, protection fell dramatically. The Oxford team suggest this might not be as problematic as it sounds. According to the World Health Organisation, deaths from the mosquito-borne disease peak at 1 years old, so effectively inoculating this demographic could be the key to reducing malarial deaths.

The R21 vaccine has already been approved by the World Health Organisation to be rolled out in 18 African countries over the next two years, signaling new hope in eliminating the disease.

Indeed, Cape Verde announced it was the fourth country in Africa to eradicate Malaria this week, alongside Algeria, Morocco and Mauritius.

Professor of Immunology and Infectious Disease at the University of Edinburgh Eleanor Riley, commends the quality of the research but notes one important caveat, “none of the five sites in the study represents an area of intense, perennial malaria transmission such as is seen – for example – in central Africa. This is the ultimate test of any malaria vaccine.”