Malaria Vaccine Candidate Yields Promising Results in Trial

 

 

 

African children under age 5 suffer a greater risk from malaria than any other demographic group.

 

 

By Charlene Porter
20 October 2011

Washington — Researchers and government health officials express measured optimism about a malaria vaccine candidate that has produced positive results in trials involving more than 15,000 children across 11 sites in seven countries in Africa, where the disease causes the most deaths.

The vaccine is known as RTS,S and it has provided “young African children with significant protection against clinical and severe malaria with an acceptable safety and tolerability profile,” according to the October 18 press announcement made by the Malaria Vaccine Initiative (MVI) and GlaxoSmithKline (GSK) Biologicals, two of the main partner organizations that conducted the trial.

The vaccine works by prompting the body’s immune system to defend itself against Plasmodium falciparum, the malaria parasite carried by mosquitoes. The vaccine was first developed at GSK Biologicals headquarters in Belgium and was successfully tested on U.S. adult volunteers. The current trial results from a proposal by MVI that RTS,S could be useful in protecting African children, who make up about 90 percent of the some 800,000 fatalities caused by malaria each year.

Researchers collected data on the first 6,000 children 12 months after they received three doses of the vaccine. Those aged 5 to 17 months were shown to have reduced risk of clinical malaria — marked by fever and chills — by 56 percent. Children had a 47 percent lower risk of contracting severe malaria, which becomes a medical emergency with a patient exhibiting coma, severe anemia, respiratory distress and potential organ damage.

The consequences of severe malaria in children can be persistent and debilitating. If the disease reaches the brain, cerebral malaria can develop, which can lead to long-term trouble with movement, palsies, speech difficulties, deafness and blindness.

Dr. Tsiri Agbenyega, a principal investigator of the trial, called the results “an important milestone in the development of RTS,S.”

Rajiv Shah, U.S. Agency for International Development (USAID) administrator, welcomed the initial evidence for the vaccine. “The vaccine, as a new addition to our present package [of] malaria control interventions, could result in further major reductions in severe malaria cases and deaths,” Shah said in a press statement. “RTS,S as a first-generation vaccine is an important first step in collaborative efforts to develop the next generation of even more effective vaccines.”

The research to find an effective vaccine has been conducted at the same time international health donors have been working to step up malaria prevention with distribution and information campaigns about the use of bed nets to protect from biting mosquitoes and household spraying to deter the insects.

“Over the past five years, global action to combat malaria has saved an estimated 1.1 million lives in sub-Saharan Africa,” Shah said. “African countries are now poised to achieve the first great humanitarian victory of the 21st century: near-zero child deaths from malaria.”

Efforts to reduce the incidence of malaria and the fatalities it causes have been pursued under a number of U.S. programs, including the President’s Malaria Initiative, the President’s Emergency Plan for AIDS Relief (PEPFAR) and the Global Health Initiative. The United States has also been a major contributor to the Global Fund to Fight AIDS, Tuberculosis and Malaria.

Striving to improve children’s health has been an imperative of these efforts, in the belief that healthy children can become healthy, productive adults who have greater capability to thrive in their own lives and as citizens of their countries. A few studies conducted in recent years have demonstrated that the occurrence of chronic disease with lifelong consequences can keep adults in lifelong poverty and stifle national aspirations for development.

The Bill & Melinda Gates Foundation has been an important global donor and a moral force in mustering support for improving health in the world’s poor. The MVI-GSK results, in fact, were announced at a Gates Foundation Malaria Forum, upon their publication in the New England Journal of Medicine.

“A vaccine is the simplest, most cost-effective way to save lives,” Gates said in a statement. “These results demonstrate the power of working with partners to create a malaria vaccine that has the potential to protect millions of children from this devastating disease.”

The U.S. Centers for Disease Control and Prevention (CDC) collaborated with the Kenya Medical Research Institute to conduct the trial at one of the East African sites. CDC Director Thomas R. Frieden said in a press release that data to be collected in the future will be critical to understanding the usefulness of RTS,S. “Those data, expected in 2012 and 2014 … will be critical to understanding how the vaccine may be used to control malaria,” Frieden said.