GENEVA - The World Health Organisation on
Friday gave countries two weeks to replace a problem polio vaccine
blamed for some outbreaks of the crippling disease, which the UN health
agency is hoping to wipe out once and for all.
A health worker gives a young boy drops of oral polio vaccine on April 7, 2014 in an outskirt of the Yemeni capital Sanaa
WHO has warned that the live polio virus used in some vaccines is one of the biggest obstacles to eradicating the disease.
For the past year and a half, 155 countries and territories
have been gearing up to make the shift away from the problem vaccine,
with the big switch set to begin on Sunday and to be completed by May 1,
WHO said.
"The switch is a significant milestone in the effort to achieve a polio-free world," WHO said in a statement.
A massive global effort has in recent decades come close to
wiping out polio, a crippling and potentially fatal viral disease that
mainly affects children under the age of five.
Cases have decreased by 99 percent since 1988, when polio
was endemic in 125 countries and 350,000 cases were recorded worldwide.
The wild version of the virus now exists only in Afghanistan
and Pakistan, but a type of vaccine that contains small amounts of
weakened but live polio still causes occasional outbreaks elsewhere.
Oral polio vaccine (OPV) replicates in the gut and can be
passed to others through faecal-contaminated water -- meaning it won't
hurt the child who has been vaccinated, but could infect their
neighbours.
Long-term, WHO recommends that the OPV should be phased out worldwide and replaced by the inactivated polio vaccine (IPV).
But due to a range of constraints, including shortages of supply, the shift is expected to take a while.
In the meantime, the WHO Strategic Advisory Group of
Experts, which advises the agency on immunisation, has called for the
withdrawal of one form of OPV considered to be at the root of the
problem.
The trivalent vaccine protects against all three types of
polio, including type 2, which no longer exists in the wild but which
causes most vaccine-derived outbreaks.
By the end of this month, countries will simultaneously swap
out that vaccine with the bivalent version of OPV, which only protects
against polio types 1 and 3.
Since the problem vaccine contains a small dose of type 2
polio, the switch needs to be coordinated to prevent outbreaks in places
where the trivalent vaccine is no longer being used.
When the switch is done, "approximately 300 million doses of
bivalent OPV will be used in routine immunisation programmes around the
world" annually, WHO spokesman Oliver Rosenbauer told AFP.
Thousands of independent monitors will deploy worldwide to confirm that the problem vaccine is no longer being used, WHO said.
Post a Comment