After a two-day meeting in Geneva, Switzerland, the World Health Organisation (WHO) recommended extra safety precautions for Sanofi’s dengue fever vaccine, Dengvaxia. WHO said on Thursday that the vaccine should only be used after testing to confirm an individual has been previously been infected.
“We have now clear information that the vaccine needs to be dealt with in a much safer way by using it exclusively in people already infected with dengue before,” Alejandro Cravioto, chair of the WHO’s Strategic Advisory Group of Experts (SAGE) on Immunisation, told reporters on a conference call.
“It requires for the people to be tested through a system that is not currently available but that we feel will be developed in the next years,” Cravioto said. Since no such test is available, the new guidelines substantially limit the market for Dengvaxia.
The French pharmaceutical company has been entangled in controversy over the vaccine, which was first approved in late 2015. Last November, Sanofi warned that Dengvaxia could increase the chances of developing severe dengue in people who had never been exposed to the virus. Safety concerns and public uproar in the Philippines led the government to suspend Dengvaxia, which had been used between 2016 and 2017 in a large-scale vaccination campaign for school-aged children.
In February, a government-ordered inquiry in the Philippines found Dengvaxia could be linked to up to three deaths in the country, but Sanofi has said it is unaware of any deaths caused by the vaccine. The company has remained firm that it is dedicated to improving health around the world and said it would continue to cooperate with authorities.
“We are confident in Dengvaxia’s safety and its proven potential to reduce dengue disease burden in endemic countries,” Sanofi said in a statement quoted by Reuters. Sanofi added that it would “continue to work with the international public health community and endemic countries, to ensure the best usage of the vaccine.”
Mosquito-borne dengue affects up to 100 million people worldwide and is the world’s fastest-growing infectious disease. Each year, the disease causes half a million life-threatening infections and kills around 20,000 people, most of them children. The disease is most dangerous when a person is infected more than once.
According to Reuters, Dengvaxia has been approved and registered in 19 countries and is currently being reviewed by the European Medicines Agency. Although Dengvaxia is the world’s first dengue fever vaccine, Brazil’s Butantan Institute, the United States National Institute of Health and Japan’s Takeda Pharmaceutical are working on rival products.
David Loew, head of Sanofi’s vaccines division Sanofi Pasteur, told Reuters in an interview last month that the company was in talks with external partners and universities to develop a test for individuals prior to vaccination with Dengvaxia. However, Loew said it would be at least two years before the test would be available on the market.