Sanofi's Dengvaxia scrutiny mounts as Philippines slams brakes on dengue shots

The Philippines has put a vaccination program of Sanofi's Dengvaxia on hold after study revealed potential health risks in dengue-naive populations. (Sanofi/Vincent Moncorgé)

The Philippines was the first country to introduce Sanofi’s dengue vaccine in a national campaign, and it’s now the first to react after Sanofi flagged Dengvaxia’s dangers to people not previously infected with the virus.

The country suspended a 3.5 billion-peso ($70 million) mass immunization program and launched an investigation to dig into a "shameless public health scam" that put lives at risk, a top spokesperson told Reuters.

On the heels of the Sanofi announcement, WHO says it is conducting a "full review" of the vaccine and will provide a "revised guidance" for its use. For now, though, WHO "recommends that Dengvaxia is only administered to subjects that are known to have been infected with dengue prior to vaccination."

In the Philippines, the Department of Health's vaccination program provided free Dengvaxia to public school students in three highly endemic regions. Since it began last April, more than 700,000 children have received at least one dose in the three-shot regimen.

RELATED: Sanofi takes €100M charge after Dengvaxia analysis leads it to seek smaller label

The halt came soon after Sanofi reported that Dengvaxia could prevent severe illness for at least 30 months in those who've never been infected. But if those patients contracted the virus naturally later on, their illness would likely be more severe.

That conclusion is in line with findings from another study last year, and the World Health Organization originally recommended that the vaccine only be introduced in regions with a high dengue burden.

That’s exactly what the Philippines did, but the new analysis quickly set off alarms among Filipinos. After all, even in the most endemic areas in a WHO-marked highly endemic country like the Philippines—which has recorded roughly 200,000 dengue cases annually in recent years—it’s likely that some children haven't been exposed to the virus prior to vaccination.

Sanofi says it's cooperating with the investigation. Medical director Ruby Dizon said there had been no Dengvaxia-related deaths reported in the Philippines.

“Of course, rest assured, monitoring is continuing; we are working with the Department of Health (DOH) in collaboration, to make sure this is maintained,” she said, as quoted by the BBC.

RELATED: Sanofi's Dengvaxia could do more harm than good in certain settings, study says

DOH spokesperson Lyndon See Uy, according to local media outlet the Philippine Star, said Sanofi and WHO have different definitions of “severe dengue.” Sanofi said dengue hemorrhagic fever IV, the most severe form categorized by the WHO, was not seen in those vaccinated, and that study participants who contracted severe dengue, whether vaccinated or not, have fully recovered.

The Department is currently tracking the medical history of about 70,000 children who were vaccinated under the program considered most at risk. The President’s office and the Department of Justice, on the other hand, are treating the issue with a tougher stance.

Philippine Justice Secretary Vitaliano Aguirre II has ordered the National Bureau of Investigation to conduct a probe into the conduct of officials involved in the project, which was started by former health secretary Janette Loreto-Garin.

“We will leave no stone unturned in making those responsible for this shameless public health scam which puts hundreds of thousands of young lives at risk accountable,” Reuters quoted Presidential spokesman Harry Roque as saying in a statement.

RELATED: Aiming for Dengvaxia boost, Sanofi pushes for campaign deals in Mexico, Asia

Sanofi is asking regulators to change the vaccine’s label based on the new trial-data analysis and is asking physicians to take an individual’s previous exposure to dengue into account when prescribing the vaccine. The company expects to take a related €100 million ($119 million) charge in the fourth quarter.

Last year, a study published in Science by a team at Imperial College London found the same issue with the vaccine. Speaking with FiercePharma in response, Sanofi Pasteur’s director of global medical affairs for dengue, Dr. Cesar Mascareñas, said the study didn’t change Sanofi’s expectations or strategies for the program because it was only a “mathematical model” and not “evidence-based.” Additionally, he said, it was one of eight models considered by the WHO in making its initial recommendation that the vaccine be used in countries where the virus is more than 50% prevalent.

"It’s not new information for the experts," he said at the time. "It has been taken into account by the experts at the WHO."

Mascareñas said key to the Dengvaxia rollout would be public immunization campaigns in Mexico, which seriously considered such a program, and throughout Latin America and Asia. But nearly two years to the date after Mexico's approval, the Philippines and Brazil remain the only two countries to have introduced the shot in government campaigns, according to the WHO.