Photo: CDC/Wikipedia
Malaria kills around 1,300 children every day in sub-Saharan Africa alone, and so far no vaccine has been approved that would successfully reduce that number. However, that may be about to change. In what would be a huge step forward if it gets the necessary approvals, a candidate vaccine is being considered that could be available by October this year.
The Huffington Post reported that vaccine candidate RTS,S/AS01 has reached an advanced stage of clinical testing in humans, and has been found to be partially effective in preventing malaria in African children for up to 4 years after they have been vaccinated. The vaccine has been in trials since 2009 and the final stage data wad published in The Lancet journal in April 2015.
Although it does not offer complete protection against the illness, the researchers developing the vaccine believe that it could prevent a substantial number of cases each year if it goes into widespread use. In the trials, for every 1000 children who received the vaccine there were 1,363 fewer cases of clinical malaria over a 4 year span than for children who did not receive the malaria vaccine (the other children got vaccines for other illnesses). What that means is that many children who did not get the vaccine got malaria multiple times, which is why the number of cases prevented is over 1000.
Malaria is an illness caused by a parasite that gets into the blood and liver of infected persons. Children who got the vaccine had fewer reported cases of both clinical malaria and severe malaria, the distinction between the two being the number of the parasites in a given volume of blood.
The vaccine was administered to babies in three doses one month apart, sometimes followed by a booster 20 months after the first dose. Some babies received the vaccine between the ages of 6-12 weeks, while others were slightly older between 5 to 17 months. The study showed that the vaccine was more effective in the older group of babies, although it diminished in effectiveness over time in both groups. A booster dose at 20 months prolonged the protection and increased the average number of cases prevented in both children and young infants. With a booster dose, an estimated 1,774 infections were prevented.
“Despite the falling efficacy over time, there is still a clear benefit from RTS,S/AS01,” Brian Greenwood, corresponding author and Professor of Clinical Tropical Medicine at London School of Hygiene & Tropical Medicine in the UK said. “Given that there were an estimated 198 million malaria cases in 2013, this level of efficacy potentially translates into millions of cases of malaria in children being prevented,” Greenwood said.
“The European Medicines Agency (EMA) will assess the quality, safety, and efficacy of the vaccine based on these final data. If the EMA gives a favourable opinion, WHO [World Health Organization] could recommend the use of RTS,S/AS01 as early as October this year. If licensed, RTS,S/AS01 would be the first licensed human vaccine against a parasitic disease,” Greenwood said.
If this vaccine is approved by the EMA and the WHO, individual countries would need to decide whether to license the vaccine for general use. Although the vaccine does not completely prevent malaria, or even come close, with a vaccine efficacy rate between 18% and 28%, it would be a very promising start.
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