The malaria vaccine, combined with malaria prevention drugs, has reduced by two-thirds hospital admissions for severe disease and deaths, a new study suggests.
The reductions continued over five years, confirming the benefits of combining the RTSS, vaccine with antimalarial drugs.
The vaccine is currently being offered in eight counties in western Kenya.
By April this year, at least 400,000 children in Kisumu, Siaya, Homa Bay, Migori, Busia, Kakamega, Bungoma and Vihiga counties had received the vaccine since 2019.
Although the current study was conducted in Burkina Faso and Mali, researchers suggest the outcome would probably be similar in other regions.
“Compared with seasonal malaria chemoprevention (SMC) alone, the RTSS-SMC combination reduced by two-thirds hospital admissions for WHO-defined severe malaria (66.8 per cent), malarial anaemia (65.9 per cent), blood transfusions (68.1 per cent), and malaria deaths (66.8 per cent),” says the study, published on Tuesday in the journal Lancet Infectious Diseases.
It was coordinated by the London School of Hygiene & Tropical Medicine with its partners. Researchers followed more than 5,000 children over a total of five years. The study also confirmed that the efficacy of the vaccine in preventing malaria in highly seasonal settings was similar, or “non-inferior,” to that of prevention drugs.
The findings from five years of follow-up are consistent with those from the first three years, which were published in 2021.
The 2021 findings contributed to the World Health Organization’s decision that year to recommend the vaccine for use in settings of moderate-to-high malaria transmission, such as western Kenya.
“These new findings confirm the potential of seasonal vaccination to provide a high level of protection in young children over the first five years of life, a period when this protection is needed,” the study authors said.
LSHTM’s Prof Brian Greenwood, a member of the research team, said, “We can say that children who received the RTSS-drug combination and also used bednets likely had greater than 90 per cent protection against malaria episodes during the study.”
He added, “This points to the importance of ensuring access to multiple malaria prevention tools for reducing the tremendous burden of malaria disease and death in these highly seasonal settings.”
Prof Jean-Bosco Ouedraogo, also a member of the research team, said, “The challenge now is to determine how best to deliver the vaccine-drug combination and to follow these highly protected children as they grow older.”
The study begun in Burkina Faso and Mali in 2017. An extension began in April 2020, when 5,048 (94 per cent) of the 5,433 children who completed the initial three-year follow-up were re-enrolled.
Over the full five years, protective efficacy of the vaccine-prevention drug combination was similar to that seen in the first three years, results suggest.
Prof Alassane Dicko, a member of the research team, said, “Rapid implementation of this new additional tool is needed to reduce the huge burden of malaria on children in our countries.”
SMC involves giving anti-malarial drugs sulfadoxine-pyrimethamine and amodiaquine to young children four or five times during the rainy season when malaria transmission peaks. It is highly effective in preventing malaria and was recommended by WHO in 2012 for use in areas with highly seasonal transmission.
Continued testing of a subset of children in the study found that the drugs currently used for SMC remain effective.
However, the study authors concluded that seasonal vaccination could be a potential solution, if resistance to the drugs increases and no alternatives are available.
The study took advantage of the fact that the vaccine’s efficacy is highest in the months immediately after vaccination, at about 70 per cent, the authors said.
There were no safety issues following multiple annual booster doses of the vaccine, with some children receiving four seasonal booster doses after the initial three-dose primary series, authors said.