Philippines halts dengue immunisation campaign owing to safety risk

The Philippines has halted a dengue immunisation campaign and all marketing of the world’s first approved dengue vaccine, Sanofi Pasteur’s Dengvaxia, after post-market testing confirmed that it can increase the risk of severe dengue in people who have never been exposed to the virus.

The vaccine is at the centre of a growing political scandal in the Philippines, where 830 000 schoolchildren have already been vaccinated in a campaign that continued unmodified despite a World Health Organization warning in July 2016 that Dengvaxia may pose a threat to people who had never been infected.

As anti-vaccine protestors demonstrated outside the Philippines Congress, President Rodrigo Duterte’s administration and its supporters in the Senate suggested that corruption and political considerations had played a role in what it called an unusually truncated approval process for the immunisation campaign during the previous administration, under President Benigno Aquino III.

Francisco Duque III, health secretary, accused the vaccine’s maker of “mental dishonesty” in minimising risks from the vaccine. “They [Sanofi] could have been more forthright,” he told a Senate panel on 11 December.

Duque said that the Philippines will request a full refund of the 3.5bn pesos (£52m; €59m; $69m) that the country paid for the vaccine used in the campaign. He also expects Sanofi to cover the cost of treating vaccinated children who contract severe dengue.

Reviewing old trial data using an assay that can identify patients with antibodies to wild dengue, Sanofi found that, although the vaccine reduced hospital admissions overall in endemic areas among a subset of recipients with no previous exposure to the dengue virus, it tended to increase symptom severity when dengue did occur despite vaccination.1

The Philippines health ministry said that about 90% of people vaccinated had been infected by dengue previously, leaving about 80 000 potentially at risk of more severe disease.

Sanofi’s regional head, Thomas Triomphe, urged the Philippines to lift Dengvaxia’s suspension, calling it “a regression in the country’s approach in solving a major public health concern and a disservice to the Filipino people.”

Banning the vaccine “would in effect leave 90% of the population at the mercy of an epidemic which has been found to be preventable,” he told the Senate. There is “not one single death causally linked to the vaccine,” said Triomphe, who added that Dengvaxia was registered in 19 countries and used in 11.

Singapore has issued advice warning people without previous dengue exposure to avoid the vaccine. India delayed approval of Dengvaxia this year, citing insufficient research, and government officials suggest that the delay is likely to continue. The Indian company Sun Pharma said in October that it had developed a dengue vaccine that is safe in seronegative people.

WHO has clarified in a statement that it does not recommend that any country should add Dengvaxia to national vaccination programmes. It said, “Rather, WHO outlined a series of considerations national governments should take into account in deciding whether to introduce the vaccine, based on a review of available data at the time, along with possible risks.”2