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African scientists optimistic about malaria vaccine

English.news.cn   2012-11-20 20:30:11            

By Robert Manyara

KISUMU, Kenya, Nov. 20 (Xinhua) -- Researchers working on the development of a vaccine against malaria have expressed optimism over the availability of the immunization in the public health system after trials proved positive.

The trials that started in Siaya a district in western region of Kenya three years ago and other 11 researcher centers in seven African countries have proved that the vaccine can help protect infants against Malaria.

"When compared to immunization with a control vaccine, infants between six to 12 weeks have one-third fewer chances of both clinical and severe Malaria," said the research findings published in the England journal of medicine.

According to Siaya Malaria Vaccine Research Site Coordinator Chris Odero the trials have proved that the fight against malaria can be won after the third phase of the vaccine trials proved positive.

"We are on track in the development of RTS,S as the first malaria vaccine for African children. The study indicates that it can help to protect young babies against malaria. We observed that it works best with the usage of bed nets by the trial participants, " Odero told Xinhua on Tuesday.

The trial proved that the vaccine when administered along with standard childhood vaccines, among infants aged 6 to 12 weeks during first vaccination could reduce Malaria infection by 31 percent and 37 percent against clinical and severe malaria respectively.

Eleven African research centers in seven African countries are conducting this trial, together with GlaxoSmithKline (GSK) and the PATH Malaria Vaccine Initiative (MVI), with grant funding from the Bill & Melinda Gates Foundation to MVI.

"We have made significant progress in recent years in our battle against malaria, but the disease still kills 655,000 people a year - mainly children under five in sub-Saharan Africa," said Dr. Salim Abdulla, a principal investigator for the trial from the Ifakara Health Institute, Tanzania.

The study also proved that the vaccine provided protection beyond existing malaria control interventions since 86 percent of the trial participants were already using insecticides treated bed nets.

The effectiveness of the vaccine dropped among children aged between five to 17 months of age against clinical and severe malaria was 56 percent and 47 percent, respectively.

"The efficacy is lower than what we saw last year with the older five to 17 month age category, which surprised some of us scientists at the African trial sites. It makes us even more eager to gather and analyze more data from the trial to determine what factors might influence efficacy," Abdulla added.

The researchers however recommended a follow-up in this Phase III trial to provide more data for analyses to better understand the different findings between the age categories.

"While the efficacy seen is lower than last year, we believe these results confirm that RTS,S can help provide African babies and young children with meaningful protection against malaria," Sir Andrew Witty, CEO, GSK said.

He said the findings take the study to another important step forward on the journey towards having a new intervention available against malaria which is a huge burden on the health and economic growth of Africa.

On its safety, the scientist recorded an increase of serious adverse effects among infants vaccinated with RTS,S and those who did not receive.

The major side effects recorded included local injection site reactions which were less frequent following RTS,S vaccination compared to other types of vaccines.

"We were also glad to see that the study indicated that RTS,S could be administered to young infants along with standard childhood vaccines and that side effects were similar to what we would see with those vaccines," Odero said.

David Kaslow, Director of the PATH Malaria Vaccine Initiative, said determining the role of RTS,S in Africa will depend on analyses of additional data.

He said success in developing malaria vaccines depends on many factors top among them is the partnerships and robust evidence, coupled with an understanding that different combinations of tools to fight malaria.

He said the reduction in efficacy level should not be a reason to worry since developing a vaccine against a parasite is a very hard thing to do with changing adaptation.

"The efficacy came back lower than we had hoped, but developing a vaccine against a parasite is a very hard thing to do. The trial is continuing, and we look forward to getting more data to help determine whether and how to deploy this vaccine," Kaslow said.

He said more data on the longer-term efficacy of the vaccine during 30 months of follow-up after the third dose, and the impact of a booster dose are expected to be publicly available at the end of 2014.

The vaccine is being developed in partnership by GSK and MVI, together with prominent African research centers.

The collaborators are represented on the Clinical Trials Partnership Committee, which oversees the conduct of the trial. An extended team of organizations work on RTS,S, including scientists from across Africa, Europe, and North America.

Editor: Hou Qiang
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