A major step against the virus responsible for dengue fever was taken earlier this December when Mexico became the first nation to approve the use of a vaccine to help curb the mosquito-borne disease.

On December 9, the French-based pharmaceutical company Sanofi announced that Mexico health officials, via the Federal Commission for the Protection against Sanitary Risks (COFEPRIS), had officially given the go-ahead to Sanofi’s Dengvaxia®, a dengue vaccine containing protection against its four major subtypes (a fifth was identified in 2013, though there is limited evidence that it regularly infects people). The development of the vaccine, which involved multinational clinical trials of more than 40,000 volunteers, was in many ways a gamble and one that took decades to come to fruition.

“When Sanofi set out to develop a dengue vaccine 20 years ago together with local and global public health and scientific communities, it was with the intention of developing an innovative vaccine to tackle this global public health need,” said Dr. Olivier Brandicourt, Chief Executive Officer of Sanofi in a statement. “Today, with this first marketing authorization of Dengvaxia®, we have achieved our goal of making dengue the next vaccine-preventable disease. This is a historic milestone for our company, for the global public health community and, most importantly, for half the world’s population who lives at risk of dengue.”

Dengue is currently one of the most rapidly spreading infectious diseases worldwide. The World Health Organization cites research estimating that nearly 400,000 million people are infected annually, though only one-fourth (100 million) are believed to come down with noticeable symptoms. Dengue can range from a very survivable flu-like illness with joint pain to a rare life-threatening hemorrhagic fever (DHF) that sends the victim into shock. The risk of DHF becomes larger for dengue survivors reinfected with another strain (infection confers lifelong immunity, but only against that particular strain). That makes the emergence of a vaccine vital even for regions where dengue is commonly found.

Though indeed a milestone, Dengvaxia® is no miracle. In the two phase III trials conducted of it, it ultimately provided an overall protection rate against dengue of 60 percent, with varying levels of success among the four subtypes, and a noticeably weaker effectiveness in children younger than 9. Likely for that reason, the vaccine in Mexico will only be recommended for people from the ages of 9 to 45 living in endemic areas. 

Crucially, however, research published in the New England Journal of Medicine (NEJM) this past January found that the vaccine reduced the risk of dengue-related hospitalizations by 80 percent. Should that effectiveness hold up, it would greatly lower the burden dengue inflicts on human health. The degree of severe complications from the vaccine appears to be minimal as well, though researchers will continue to follow clinical trial participants for six years to make sure.

“Dengue is a growing health threat in Mexico and many other tropical and subtropical countries in Latin America and Asia. The first vaccine approved to prevent dengue fever is a major innovation and a public health breakthrough. Dengvaxia® will be a critical addition to the integrated dengue prevention and control efforts. It will be an essential tool to boost on-going community efforts to relieve the long-standing suffering that this disease continues to bring to people in endemic countries like ours,” said José Luis Arredondo García, Associate Director of Clinical Research in the National Institute of Pediatrics in Mexico City, as well as a research member of the January NEJM study.

Banking on the vaccine’s success years before it happened, Sandofi’s already built facility at Neuville-Sur-Saône, France, will be able to produce 100 million doses annually at full capacity. As of now, the vaccine will be available in Mexico by early next year, though the country has not yet determined whether it will sponsor any widespread vaccination programs. The company is currently seeking in the middle of seeking vaccine approval from other nations.