http://www.nature.com/news/2011/111026/full/478439a.html
Para alguien como yo que contrajo 3 veces la terrible enfermedad malaria en Africa, esta nota de NATURE es alentadora.
News
Malaria vaccine results face scrutiny
Experts question early release of incomplete trial data.
The RTS,S/AS01 candidate vaccine offers poor protection against severe malaria.Reuters/J. Okanga
"Malaria
vaccine could save millions of children's lives"; "World's first
malaria vaccine works in major trial"; "Malaria vaccine almost here". To
judge from last week's headlines, scientists had made a big
breakthrough in the long campaign to create a malaria vaccine, proving
its effectiveness with interim results from a huge phase III clinical
trial in Africa
1.
Yet several leading vaccine researchers, who are critical of the
unusual decision to publish partial trial data, argue that the results
raise questions about whether the RTS,S/AS01 candidate vaccine can
actually win approval.
RTS,S has been in development for some 25 years, initially by the US
military, and since 2001 by a public–private venture between the PATH
Malaria Vaccine Initiative (MVI) and the drug-maker GlaxoSmithKline
(GSK), supported by US$200 million in funding from the Bill &
Melinda Gates Foundation. Bill Gates himself announced the interim
results at the Gates Malaria Forum in Seattle, Washington.
Gates' speech and the MVI's public-relations material were suitably
circumspect about the results, but they were "immediately translated
into headlines about [reductions] in death and mortality", says Andrew
Farlow, an economist at the University of Oxford, UK, who has previously
assessed the RTS,S programme
2. "But the data are not telling you that at all."
Some researchers question whether the results should have been
published before all the data were available; full results are expected
in 2014. Interim trial data are usually reported only to regulatory
authorities, and clinical trials published only once all the data are
in, noted Nicholas White, a malaria expert at Mahidol University in
Bangkok, in an editorial
3
accompanying the interim results. "There does not seem to be a clear
scientific reason why this trial has been reported with less than half
the efficacy results available," he wrote.
The publication presents vaccine-efficacy data for infants aged
5–17 months, but not for those aged 6–12 weeks, who are the stated
target of the trial: it is this group that would receive the malaria
vaccine alongside routine immunizations. The aim of the trial is to
provide the World Health Organization (WHO) with the information it
needs to consider licensing the vaccine, and recommend it for use in
that age group. "What is the point of publishing the interim data on the
5–17-month-olds?" asks Stephen Hoffman, a veteran malaria researcher
and chief executive of a rival vaccine effort, Sanaria, based in
Rockville, Maryland.
The MVI's director, Christian Loucq, argues that the results were
"robust enough to be published. We decided this before we knew the
results; we felt it was our scientific and ethical duty to make the
results public when they become available."
One of the biggest claims made in the paper is that RTS,S reduced
the total number of episodes of clinical malaria in the older group by
55.1%, compared to controls. This measure of efficacy is recommended for
assessing a partially effective vaccine
4.
But the public expects vaccine efficacy to describe protection over a
period of time, argues Judith Epstein, a captain and paediatrician at
the US Military Malaria Vaccine Program in Silver Spring, Maryland.
Recalculating the trial data shows that RTS,S protected just 35–36%
after 12 months, she says, adding that the paper should have presented
both numbers. The study also showed no detectable impact on mortality,
and it is too early to tell whether RTS,S actually protects against
malaria, or merely delays infection.
The paper did report that RTS,S reduced severe malaria by 47% in the
older group. But combining that result with available data from the
younger age group cut that number to 34.8% — meaning that for the
youngest children, the benefit must be even smaller. "The real question
mark is the 34.8% efficacy in severe disease," says Blaise Genton of the
Swiss Tropical and Public Health Institute in Basel, and a member of
the WHO technical advisory group for RTS,S. The results suggest that the
vaccine might fall short of expectations, laid out in 2006 by a WHO-led
consortium
5,
that it should have a "protective efficacy of more than 50% against
severe disease and death and lasts longer than one year". "If it doesn't
reduce deaths, and has only a modest effect on severe malaria, these
are going to be big questions for decision-makers at WHO, GSK and the
Gates Foundation," says Hoffman.
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Another worrying finding is that the frequency of serious adverse
events, such as convulsions and meningitis, was significantly higher in
the vaccinated group, although the data are too preliminary to draw firm
conclusions.
But Hoffman, like many researchers contacted by
Nature, says that RTS,S still marks a significant achievement. It is the first vaccine against a parasite,
Plasmodium falciparum,
to consistently show a significant protective effect in large-scale
trials. The phase III trial of RTS,S resulted in groundbreaking
cooperation with African scientists, who led the 11 trials in 7
countries, says Hoffman. "I think that those teams deserve an incredible
amount of recognition and congratulation."
This article originally described Plasmodium falciparum as
multicellular instead of unicellular. The error has now been removed
from the text.
Les règles du droit international relatives à la conduite
des hostilités réglementent et limitent les méthodes et moyens de guerre
que les parties à un conflit armé peuvent utiliser. Elles ont pour but
d'établir un équilibre entre une action militaire légitime et l’objectif
humanitaire consistant à atténuer les souffrances humaines, en
particulier parmi la population civile.
