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 The shot, called RTS,S and designed for children in Africa, would be
the first licensed human vaccine against a parasitic disease and
could help prevent millions of cases of malaria, which currently
kills more than 600,000 people a year.
Experts have long hoped scientists would be able to develop an
effective malaria vaccine, and researchers at the British drugmaker
GSK have been working on RTS,S for 30 years.
Hopes that this shot would be the final answer to wiping out malaria
were dampened when trial data released in 2011 and 2012 showed it
only reduced episodes of malaria in babies aged 6-12 weeks by 27
percent, and by around 46 percent in children aged 5-17 months.
But the final stage follow-up data published in the Lancet journal
on Friday showed vaccinated children continued to be protected four
years on, albeit at a declining rate -- an important factor given
the prevalence of the disease -- and rates of protection were
stronger with a booster shot.
"Despite the falling efficacy over time, there is still a clear
benefit from RTS,S," said Brian Greenwood, a professor at the London
School of Hygiene & Tropical Medicine who worked on the study.
He said an average 1,363 cases of clinical malaria were prevented
over four years for every 1,000 children vaccinated, or 1,774 cases
with a booster shot -- the children would normally be expected to
have had several cases of infection over that period.
In babies, over three years of follow-up, an average 558 cases were
prevented for every 1,000 vaccinated, and 983 cases in those who got
a booster.
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"Given that there were an estimated 198 million malaria cases in
2013, this level of efficacy potentially translates into millions of
cases of malaria in children being prevented," Greenwood said.
GSK submitted an application in July 2014 for regulatory approval by
the European Medicines Agency for RTS,S and is expecting a decision
within a few months. If it gets a license, the World Health
Organization could recommend it for use "as early as October this
year", Greenwood said.
Experts say RTS,S will be only one among several weapons against
malaria, alongside insecticide-treated bednets, rapid diagnostic
tests and anti-malarial drugs.
RTS,S was co-developed by GSK and the non-profit PATH Malaria
Vaccine Initiative, with funding from the Bill & Melinda Gates
Foundation.
(Editing by Andrew Heavens)
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