A phase 2b clinical trial suggests that a booster dose of the potential malaria vaccine R21/Matrix-M is very effective in youngsters. In Nanoro, Burkina Faso, 450 toddlers aged 5 to 17 months participated in a phase 2b clinical trial whose results were published in The Lancet in 2021. 409 individuals received the booster dose.
The participants were administered a low dosage of the circumsporozoite protein-based vaccine R21 in conjunction with two different doses of the adjuvant Matrix-M. (MM). Before the malaria season, three immunizations were provided at 4-week intervals, followed by a booster dose one year later.
At the primary efficacy analysis at 6 months, vaccine efficacy in group 1, which received a lower dose of adjuvant, was 74%, while efficacy in group 1, which received a dose of adjuvant that was twice as high, was 77%. The adverse effects were modest, with fever being the most common. At one year, the vaccination effectiveness in group 1 remained strong at 77%.
In September 2022, researchers announced the results of a phase 2b clinical trial in which a booster dosage of R21/Matrix-M was administered 12 months after the completion of a three-dose primary series. Research published in The Lancet Infectious Diseases demonstrates vaccine efficacy of 80 percent in the higher-dose adjuvant group and 70 percent in the lower-dose adjuvant group throughout a 12-month follow-up period.
Researchers report that 28 days after the administration of booster doses, antibody levels returned to levels comparable to those following the initial series. In the trial, no major adverse effects were reported. The authors point out, however, that the limited sample size of the study limits the ability to find uncommon adverse events and a potential correlate of protection and restricts the ability to identify uncommon adverse events.
Halidou Tinto, Professor of Parasitology, Regional Director of IRSS in Nanoro, and the trial’s Lead Investigator, stated in a news release, “It is great to find such high vaccine efficacy with a single booster dosage. We are currently participating in a very large phase 3 trial with the goal of licensing this vaccine for general usage within the next year.
The phase 3 clinical research evaluates the safety and efficacy of the treatment in 4,800 children aged five to thirty-six months across four African nations. Malaria is a potentially fatal disease caused by Plasmodium parasites that are transmitted by the bites of infected female Anopheles mosquitoes.
According to the World Health Organization’s most recent data on global malaria, in 2020, there were 241 million cases of malaria and 627 thousand deaths (WHO), Africa is responsible for more than 90 percent of malaria infections and fatalities. The sickness is extremely harmful for infants, children under the age of five, pregnant women, HIV/AIDS patients, and anyone with a compromised immune system.
To prevent malaria, the WHO recommends widespread use of the RTS, S/AS01 vaccination among children living in locations with moderate to high Plasmodium falciparum transmission, the most lethal parasite species responsible for the disease.
The RTS, S/AS01 vaccine, also known as Mosquirix, demonstrated the effectiveness of 31.3% in newborns aged 6–12 weeks and 55.8% in children aged 5–17 months in phase 3 clinical trial.
