MANILA - The manufacturer of the world’s first dengue vaccine has admitted the drug may be harmful when administered to individuals not previously infected with dengue.
Sanofi Pasteur said Wednesday it has a new analysis of long-term clinical trial data on dengue vaccine Dengvaxia.
“Dengvaxia provides persistent protective benefits against dengue fever in those who had prior infection. For those not previously infected by dengue virus, however…more cases of severe disease could occur following vaccination upon a subsequent dengue infection,” the statement read.
Newly appointed Health Secretary Fransisco Duque immediately instructed the Dengue Technical and Management Committee to meet with an expert panel to determine the next course of action.
“The safety of the children vaccinated is paramount, and the Health Department will need to do surveillance of those given Dengvaxia with no prior infection. It's really a big task," Duque said.
The Philippines was the 1st country in Asia to approve the vaccine for individuals aged 9 and 45 years old in December 2015.
Government has since procured P3-billion worth of Dengvaxia intended for one million public school children in areas reported to have the highest incidence of dengue in 2015: the National Capital Region, Region 3, and Region 4A. The vaccine was to be administered in three phases at 6 month intervals beginning April 2016.
Sanofi Pasteur's Wednesday statement was the first time the pharmaceutical company acknowledged that Dengvaxia should not be recommended to individuals if they have never been infected with the dengue virus. The manufacturer said it would ask health authorities to advise physicians and patients of the new information in countries where the drug has been approved.
FILIPINO KIDS NOT TESTED
A total of 491,990 9-year-old students were vaccinated in the first phase, under then Health Secretary Janette Garin.
Of that number, 415,681 turned up for the second phase, which by then was implemented by Garin’s successor, Secretary Paulyn Ubial.
Data is still being collated to determine how many school children completed the third and final round of vaccinations.
None of the children were ever tested to determine if they had been previously infected with the dengue virus.
“It means some of them will develop severe dengue, we don’t know who,” said Independent Health Advocate Dr. Anthony Leachon.
“All of them will have to live with this possibility for the rest of their lives.”
TESTS EXPENSIVE, TEDIOUS
The school-based dengue immunization program was Garin's brainchild.
She said implementation was based on the guidelines and parameters set by the W.H.O. or the World Health Organization.
“W.H.O. did not recommend individual testing (to determine prior infection with the dengue virus) because the current test is non-specific, meaning it turns positive for all flaviviruses including Zika, Chikungunya and Japanese Encephalitis.”
“In all areas there were no tests because we have existing prevalence and surveillance data that infection rate is high, more than the 70% set by the W.H.O.,” Ubial said.
The World Health Organization recommended the introduction of the dengue vaccine only in geographic settings with a high burden of disease.
“Doing tests to prove previous infection will be very tedious and expensive, that it would negate the cost-effectiveness of the intervention,” Ubial added.
PROCEEDED WITH CAUTION
Ubial was initially hesitant to continue the program, but eventually decided to proceed upon the advice of two expert panels.
“We proceeded with caution knowing that incomplete vaccination would have been more risky,” Ubial said.
Ubial then approved the expansion of the program to Region 7 because of a “clamor “ for its implementation.
She also approved the shift to a community based immunization program in Metro Manila and Cebu following advice that some P1.5 billion worth of vaccines purchased by the previous administration would expire and go to waste.
Several health experts, including Leachon, had already warned government long before about the possible adverse effect of the new drug on individuals with no prior history of dengue, citing a study published in Science Online Journal.
“The Department of Health must now address the possibility of harm in the mass dengue vaccination program,” Leachon said.
“Congress should also review the accountability of people involved in this initiative,” he added.