Please: Login/Register

The Latest Edition of "Eyes on malaria" magazine will be out very soon!! | CALL FOR ARTICLES: AMMREN is inviting journalists / writers / scientists interested in reporting on malaria to send articles for publication in its international magazine “Eyes on Malaria” and for posting on its website. Please contact the AMMREN Secretariat for more details click here. Enjoy your stay!. Volunteers and interns urgently needed to work with an NGO working in the area of malaria and health. Apply through - ammren1@gmail.com / ammren1@yahoo.com. Journalists interested in reporting on and writing articles on health issues should please reply through this email: ammren1@gmail.com

ANNOUNCEMENTS:::

TIPS ON MALARIA

  • HOW CAN MOSQUITOES BE CONTROLLED?

    Mosquitoes around the home can be reduced significantly by minimizing the amount of standing water available for mosquito breeding. Residents are urged to reduce standing water around the home in a variety of ways.

  • HOW CAN I PROTECT MYSELF FROM MOSQUITO-BORN DISEASES?

    The best way is to avoid being bitten by mosquitoes.This can be accomplished using personal protecting  while outdoors when mosquitoes are present. Treated bed nets should be used sleeping. Mosquito repellent should be used when outdoor.

  • WHO ARE AT RISK?


    Nearly half of the world’s population is at risk of getting malaria. Pregnant women are particularly at risk of malaria. Children under 5 years are at high risk of malaria.
     

MAGAZINE EDITIONS

  • Sixth Edition

  • First Edition

  • Second Edition

  • Third Edition

  • Fourth Edition

  • Fifth Edition

  • Seventh Edition

  • Eighth Edition

  • Ninth Edition

  • Special Edition

  • INESS Edition

  • Tenth Edition

  • INDEPTH Edition

  • Eleventh Edition

  • Twelfth Edition

  • Special Edition

  • Special Edition

  • March Edition

Keeping tabs on RTS,S

The idea of the RTS,S malaria candidate vaccine becoming licensed for babies, may give communities an exhilaration of victory against malaria, but it is also giving scientists cause for cogitation.

The main concern has been the decline in the potency of the vaccine over-time and how it has to be viewed against its cost and benefits. Recent findings and data on the RTS,S showed that 18 months after vaccination, children aged five to 17 months had a 46% reduction in the risk of clinical malaria compared to unvaccinated contemporaries.

But in infants aged six to 12 weeks at the time of vaccination, there was only a 27% reduction in risk. Those who have followed updates on the RTS,S from Seattle, USA in 2011 through to the recent conference in Durban, South Africa are aware of the great decisions that need to be made as soon as possible.

Against the expectation that the malaria vaccine should have a "protective efficacy of more than 50% against severe disease and death and last longer than one year," some are even asking whether RTS,S actually protects against malaria, or merely delays infection.

Bill Gates, co-founder of the Bill & Melinda Gates Foundation, has said that “The trial is continuing and we look forward to getting more data to help determine whether and how to deploy this vaccine.” This has been interpreted by some observers as ambivalence.

Meanwhile, GlaxoSmithKline (GSK), the drug maker has said in a statement that based on the RTS,S vaccine's efficacy it intends to submit in 2014 a regulatory application to the European Medicines
Agency (EMA).

In other words, it is seeking regulatory approval for the world's first malaria vaccine RTS, S, (also called Mosquirix) which it has been developing for three decades.

Commenting on the protection offered by the vaccine, Professor of Medicine at the Oxford University, UK, Timothy Edward Alexander Peto said, “An efficacy of only one-third is probably too low to be useful clinically.”

Prof Tim Peto, as he is commonly known, a researcher in tropical diseases and clinical medicine, also said that even the figures are overestimated because the vaccine's efficacy seems to wane over time.

He said “A better way of summarizing the data is that the vaccine has 50% efficacy in the first 3–4 months but appears to stop working after about 6 months.”

But the developers of the vaccine contend that RTS,S has an acceptable safety profile, and helps to provide protection and that even if the vaccine is only modestly protective, it could still have significant impact, given that there are an estimated 216 million cases of malaria, and some 655,000 deaths per year, mostly in children aged under-five.

Dr. David Kaslow, the Director of the PATH Malaria Vaccine Initiative (MVI), has said that more work remains to be done.

“We are awaiting additional information about how the vaccine candidate works in different malaria transmission settings and also on the effects of a booster dose of RTS,S that was administered to a subset of trial participants.

In 2011 when the initials results were announced it said 5-17 month-old children who take three doses of the vaccine, get a 56 per cent protection from clinical malaria and 47 per cent from severe malaria. Two years down the line, additional research has said that 18 months after vaccination, 5 to 17 months old children had a 46 per cent reduction in the risk of clinical malaria.

At the International African Vaccinology Conference, Cape Town, South Africa, in November 2012 it was reported that the efficacy of RTS,S in infants aged 6 to 12 weeks against clinical and severe malaria was 31 per cent and 37 per cent respectively, over 12 months of follow-up with a third dose of the vaccine.

Current results indicate however that infants aged six to 12 weeks get only 27 per cent protection. Now, researchers also find it strange that RTS,S efficacy levels differ for children in different age groups.

Last year, Tanzanian scientist and RTS,S researcher, Dr Salim Abdulla of the Ifakara Health Institute, noted “The efficacy is lower than what we saw in 2011 with the older 5 to 17 month age category, which surprised some of us scientists at the African trial sites.”

“This makes me more eager to gather and analyse additional data from the trial to determine what factors might influence efficacy against malaria and to better understand the potential of RTS,S in our battle against this devastating disease,” Dr Abdulla said.

The decline in the efficacy of the vaccine strengthens the case of experts who disagreed with the “unusual decision” to publish partial trial data, when Bill Gates (a major financier with US$200 million in funding) announced the interim results at the Malaria Forum in Seattle, Washington.

In their opinion since all the data is expected to be available in 2014, the results should not have been published before all the data is available.

Nicholas White, a malaria expert at Mahidol University in Bangkok, was famously quoted as saying: "There does not seem to be a clear scientific reason why this trial has been reported with less than half the efficacy results available.”

“Interim trial data are usually reported only to regulatory authorities, and clinical trials published only after all the data are in,” Nicholas White reportedly said in reaction
to the release of RTS,S vaccine trials results in bits.

Some experts are saying that the current results raise questions about whether the RTS,S/AS01 candidate vaccine can actually win approval. There is also reference to how almost 60% of the cases of clinical malaria observed in the current study came from just 2 of the 11 trial sites, for example.

Dr Kaslow, has been quoted as saying that “The RTS,S vaccine's efficacy might be even lower than the figure at these two sites, and higher at some other sites.”

The PATH Director is quoted as saying that if the vaccine does not perform too well in areas of intense malaria transmission as feared, it could dent the vaccine's costeffectiveness. But all that will only be known when all data are available at the end of 2014.

Dr. Kaslow says that work is now underway to apply what they are learning from the RTS,S vaccine candidate trials to other vaccine approaches.

“MVI is working on prime-boost vaccines that use one vaccine approach to 'prime' the immune response, and a second to increase or 'boost' that response,” he explains.

One of the things scientists are currently working on is to see whether they can break the malaria parasite-human transmission cycle, whose findings would no doubt be fascinating.

“ We a r e a l s o w o r k i n g o n v a c c i n e approaches that aim to break the transmission cycle of the malaria parasite between humans and mosquitoes,” adds Kaslow.

Principal Investigator in the RTS,S trials in Kenya Dr. Lucas Otieno of the Kenya Medical Research Institute (KEMRI) Walter Reed Project in Kisumu, said the children are still in the trials.

Asked whether the WHO is likely to issue recommendations in 2015 based on what they now know about the trial findings, Dr. Otieno was non-committal. “It is still very early to say whether or not
the WHO will issue any recommendations, given that it will base its decision on the findings presented to them, something which we are still working on,” he says.

No single malaria vaccine exists. The RTS,S vaccine candidate is the furthest along in the development process.

The RTS,S vaccine was invented and developed in the late 1980s in laboratories at GSK Vaccines in Belgium. It was initially tested on US volunteers as part of a collaboration effort with the US Walter Reed Army Institute of Research.

MVI partnered with GSK in 2001 to study the vaccine candidate's ability to protect young children in sub-Saharan Africa.

Malaria kills an estimated 660,000 people every year, most of whom are children under five years old in Sub-Saharan Africa. Africa's largest-ever clinical trial involving 15,460 participants, took place in Burkina Faso, Gabon, Ghana, Malawi, Mozambique, Kenya and Tanzania, under the Malaria Clinical Trials Alliance, sponsored by the Bill and Melinda Gates Foundation.

The reality of the malaria situation is such that although some progress has been made in reducing the malaria burden by over 20 per cent over the last decade, the task ahead seems a little daunting relying solely on current tools like bed nets, indoor residual spraying, artemisinin-based combination therapies (ACTs) and other measures.

This vaccine gives hope to scientists who have always believed that a potent vaccine is crucial to the global effort to eradicate malaria. And even with the low efficacy, RTS,S is expected to help in saving thousands of lives.

By Geoffrey Kamadi - Kenya

Editions: 
Eleventh Edition