After 17 years of research, Sanofi Pasteur is ready to launch Dengvaxia®, the first anti-dengue vaccine aimed at reducing infections by 25% and mortality by 50% in 128 countries in 2020. Mexico was one of the first countries to participate in clinical trials for this vaccine, which involved 40,000 people in 15 countries, and is the first place where it has been approved for people aged nine to 45 who live in areas where the disease is endemic. This has been somewhat controversial as children below nine years old are a vulnerable group and travelers often suffer from this disease. Given that 400 million people in tropical and sub-tropical countries in Latin America and Asia are in risk of being infected with dengue every year, the first 20 submissions for market approval were done in these countries.
Dengue infections are caused by four similar viruses named DEN-1, DEN-2, DEN-3, and DEN-4 serotypes, each of them interacting with different antibodies in the human blood serum. Despite being different, the four of them have the same clinical symptoms – fever, joint and muscular pain, rash, lymph node inflammation, among others. In the 1970s, the worldwide distribution of the four serotypes was uneven. DEN-1 and DEN-2 were present in Central America and Africa, while the four of them were found in Southeast Asia. In 2004, however, the four serotypes were present in all tropical and sub-tropical regions of the world.
Scientists have found that infection with one serotype protects the person from infections with the other three for a period of two or three month; however, subsequent infections can put the individual at a great risk. The fact that the disease is caused by four serotypes made the development of the vaccine more difficult. In an interview with Reuters Paris, Guillaume Leroy, leader of the dengue team at Sanofi Pasteur, stated that the vaccine works better as as an immunological booster against the four serotypes for people who have been previously exposed to dengue, and that more information is needed to conclude whether the immunization is effective among travelers. So far, the vaccine has proven to be effective in preventing 66% of new infections among individuals aged nine to 45 and 93% of the hemorrhagic form of the disease.
The production of the vaccine has already started in France. In Mexico, COFEPRIS requested Sanofi Pasteur to present a risk management plan specifically designed for the country, including keeping electronic records of everyone who receives the vaccine as well as adverse reaction reports. Collaboration with local clinics will be crucial to the success of this pharmacovigilance plan. Other countries such as India are eager to have the vaccine after one of the worst outbreaks of the disease took place in New Delhi this year causing more than 30 deaths.