December 14, 2017
MANILA
-- The World Health Organization (WHO) on Thursday advised its member countries
to limit the use of the controversial dengue vaccine Dengvaxia only to those
who had contracted the disease.
"Dengvaxia
prevents disease in the majority of vaccine recipients but it should not be
administered to people who have not previously been infected with dengue
virus," the WHO said in a statement.
It
noted that the WHO Global Advisory Committee on Vaccine Safety considered
Dengvaxia manufacturer, Sanofi Pasteur’s new results from clinical trial data
analyses.
“Those
studies indicate that increased risk of severe dengue disease in people who
have never been infected affects about 15 percent of the vaccinated
individuals. The magnitude of risk is in the order of about four out of every
1,000 seronegative patients vaccinated who developed severe dengue disease
during five years of observation,” the WHO said.
“The
risk of developing severe dengue disease in non-vaccinated individuals has been
calculated as 1.7 per 1,000 over the same period of observation. By contrast,
for the 85 percent who have had dengue disease before immunization, there is a
reduction of four cases of severe dengue per 1,000 who are vaccinated,” it
added.
The
international health body said that they raised the possibility of risk for
seronegative people, stating in a position paper published in July 2016 that
“vaccination may be ineffective or may theoretically even increase the future
risk of hospitalized or severe dengue illness in those who are seronegative at
the time of first vaccination regardless of age".
“As
this risk had at that time not been seen in the age groups for which the
vaccine was licensed, the WHO issued a conditional recommendation, emphasizing
the use of the vaccine in populations having been previously infected with
dengue virus,” it added.
The
WHO recommended that areas where the vaccine has already been administered
should enhance measures to reduce exposure to dengue infection.
“For
vaccine recipients who present with clinical symptoms compatible with dengue
virus infection, access to medical care should be expedited to allow for proper
evaluation, identification, and management of severe forms of the disease,” it
added.
In
the Philippines, some 830,000 children had been vaccinated with Dengvaxia under
a government immunization program, which has already been suspended until WHO
experts have reviewed the new developments on the vaccine.
Since
it became commercially available in 2016, Dengvaxia has been licensed in 19
countries. (WHO)
