PHA-Exch> New Malaria Vaccine Is Shown to Work in Infants Under 1 Year Old, a Study Finds

[Claudio Schuftan]

From: Vern Weitzel vern at coombs.anu.edu.au
 "[health-vn discussion group]" health-vn at cairo.anu.edu.au
http://www.nytimes.com/2007/10/18/health/18vaccine.html


By DONALD G. McNEIL Jr.

The world's most promising malaria vaccine has been shown to work in infants
less than a year old, the most vulnerable group, according to a study being
published today.

The study, being published in The Lancet, a British medical journal, was
small,
comprising only 214 babies in Mozambique, and intended to show only that the
vaccine was safe at such young ages. But it also indicated that the risk of
catching malaria was reduced by 65 percent after the full course of three
shots.

"We're now a step closer to the realization of a vaccine that can protect
African infants," said Dr. Pedro Alonso, the University of Barcelona
professor
who leads clinical trials of the GlaxoSmithKline vaccine.

If it passes much larger clinical trials set to start in seven countries
next
year, and if it is accepted by national regulatory agencies, it could be
ready
for distribution by 2012, said Dr. W. Ripley Ballou, Glaxo's vice president
for
international clinical trials.

In 2004, Dr. Alonso showed for the first time that the vaccine could protect
children against infection or death. That study of 2,022 children aged 1 to
4
showed protection from infection about 45 percent of the time.

Such a relatively low level of protection would not be acceptable in a
vaccine
in the West, but malaria is a leading killer of African children, so even
imperfect coverage is a major public health victory.

The vaccine, presently known as RTS,S and tentatively brand-named Mosquirix,
is
made by fusing a bit of outer protein of the deadly falciparum strain of the
malaria parasite with a bit of hepatitis B virus and a chemical booster —
the
latter two added to provoke a stronger immune reaction.

At least nine malaria vaccine candidates are in development, but Mosquirix
is
the furthest along. Glaxo has been refining it for 20 years and expects to
have
spent up to $600 million on it by the time it comes to market. About $100
million has been paid by the Bill and Melinda Gates Foundation through the
PATH
Malaria Vaccine Initiative.

No decision has been made about the price to be offered to poor countries
and
international health agencies. But "if a child will benefit, price will not
stand in the way," said Dr. Christian Loucq, director of the vaccine
initiative.

The vaccine is given in three injected doses. That is an obstacle in poor
countries, which have difficulties immunizing even against polio — done with
oral drops requiring no medical skill.

But even one dose has some protective effect, the Lancet study found.

It is unknown how long protection lasts. But because the youngest children
are
the most vulnerable, Dr. Alonso said, vaccination buys them time to build up
natural immunity, which is acquired by surviving multiple mosquito bites.
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