The trials look promising, but the next challenge is to keep the costs down.
Malaria is a mass killer, taking just under 800,000 lives a year. Most of them are babies and children under five. A significant number are pregnant women. It is an entirely preventable disease, caused by a parasite transmitted by mosquito bite, but the millions who live under its curse are too poor and have too few options to be able to avoid it.
The malaria vaccine [See: “Malaria vaccine partly effective” — ‘Science & Technology' page, October 20, 2011] that now appears to be within reach, following successful large-scale trials in seven African countries, is a potential game changer for the rural villagers whose children are the main victims of this ancient disease, which was named “mal'aria” for the bad air mediaeval Italians thought caused it.
Early results from 6,000 babies aged 5-17 months show that their risk of malaria was reduced by slightly more than half (56 per cent) and their chance of severe malaria — the kind that affects the brain, kidneys and blood and often kills — by slightly less than half (47 per cent).
Malaria is so common in sub-Saharan Africa that families think any fever in a baby must be the killer disease. Too often it is, and the hospitals are full of listless babies with vacant eyes on drips.
Vast numbers of bed nets impregnated with insecticide have been provided by donors and distributed in malaria-endemic regions. New drugs — compounds involving artemisinin [See: Editorial page, The Hindu, October 5, 2011] — have been developed and widely distributed to replace older antimalarials, which have been failing as the parasite develops resistance to them.
Mortality rate down
Malaria deaths have come down from more than a million to an estimated 780,000 a year, according to the latest report from the Roll Back Malaria partnership of the World Health Organisation (WHO). Three countries were certified malaria-free in the past four years, and nine more are preparing to move towards elimination — but that is out of 108 where the disease is endemic.
Since bed nets are not always effective and drugs can become ineffective, a vaccine could massively improve children's chances.
While researchers started work on a potential Aids vaccine with extraordinary and, as it turned out, misplaced optimism, many in the scientific community thought a malaria vaccine was a non-starter. Nobody had ever made a vaccine against a parasite-borne disease.
Twenty-five years on, a clutch of indomitable scientists — veterans such as Joe Cohen, who has been on the case for the past 23 years — has proved the sceptics wrong. According to Andrew Witty, chief executive of GlaxoSmithKline, the British company that has developed and trialled the vaccine, there were tears among the team when the results of the large-scale trial results came out. “It was the emotion of what they had achieved,” said Witty. “The first vaccine against a parasite-borne infection. They were overwhelmed.” The results show conclusively that it is possible to prevent many cases of malaria in babies aged 5-17 months. Most of these children still got malaria, but less frequently and less severely. There were 750 cases for every 1,000 vaccinated children over a year, compared with 1,500 cases for 1,000 children (as one child can have more than one bout of the disease) among those who were given dummy injections.
That could make a big difference in sub-Saharan Africa. There are 200m cases of malaria every year. Many children are damaged — sometimes brain-damaged — by it. Even stopping half of those cases would save millions of lives over the long term. But there is a way to go yet, with more results from the trial to come, and many uncertainties, including how much this vaccine will cost and who will be persuaded to pay.
Trial in seven countries
The trial is continuing in seven countries: Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania. It is big: there are 15,460 babies and infants involved. The data published so far in the New England Journal of Medicine concerns 6,000 of the older babies, those aged 5 to 17 months. Next year, results are expected for newborns, which are crucial, because the three-dose vaccine, which needs cold storage, must be incorporated into the routine infant vaccination schedule. All the signs are, though, that the response in newborns will be similar.
A bigger question is over the duration of the protection, which appears to have dropped from 47 per cent to 35 per cent for cases of severe malaria after 22 months. Some of the babies will be given a booster, to see whether this helps. While most side-effects were similar in children given the vaccine and given dummy jabs, there were significantly more with meningitis among those given the vaccine. “There seems to be no plausible explanation for this and it may well turn out to be a chance finding, but it cannot be ignored,” wrote malaria expert Prof Nick White in a commentary otherwise warmly welcoming the vaccine.
In three years' time, when the final results are in and the WHO has recommended its use, the scientists may hit the biggest stumbling block of all: money to roll it out. At a press conference to discuss the results, Dr. Regina Rabinovitch, director for infectious diseases at the global health programme of the Bill and Melinda Gates Foundation, was asked whether they would fund it. They would want to look at the data on efficacy, duration and safety in 2014, she said. “Would I prefer to see a 100 per cent vaccine? Certainly,” she added.
Price will be a critical factor. Witty says they will do everything they can to get it down. He is prepared to offer licences to get the vaccine produced cheaply in India or in Africa itself.
“I have got every confidence that we can get this price to a level that makes it very viable for donors to consider,” he said. “I don't want people to think this is an alternative to bed nets. This is about doing all we can to shut the door on malaria.” He recalls the hospital wards he has seen in Africa, full of malaria cases: “If you could take that burden away, imagine what the health capacity would be.” (Sarah Boseley is the Guardian's Health Editor.) — © Guardian Newspapers Limited, 2011