Vaccine development is a topic that is on the minds of everyone as the world grapples with ways to protect our health and the health of our loved ones from coronavirus. The team at Children's Health Defense decided to write an article about Dengue Fever because an important part of medicine's body of knowledge comes from the opportunity to learn from past mistakes.

Dengue fever is a common disease in more that 120 countries and, like Coronavirus, has been the target for a vaccine for many years. The development and licensure of Dengvaxia® vaccine by Sanofi  spanned more than 20 years and cost more than 1.5 billion U.S. dollars. But the development of the vaccine turned out to be tricky. Dengue vaccine antibodies can also make the infection worse, especially in infants and children who have never been exposed to the virus. The virus may actually use the antibodies created by the vaccine to spread the virus throughout the body. So an infection with dengue — when your blood already has antibodies in it — can actually enhance the disease resulting in deadly complications.

Despite the fact that Sanofi tested Dengvaxia in several large clinical trials with more than 30,000 kids globally and published the results in the prestigious New England Journal of Medicine, there were serious problems. According to epidemiologists who reviewed the data, the trials were riddled with "small inaccur­acies, missing data, and uncalculated risks." Buried in those clinical trials was a disease enhancement safety signal, but industry and the World Health Organization (WHO) turned a blind eye to the problem, calling it a "theoretical possibility."  Dengvaxia was subsequently admini­ster­ed to thousands of children in the Philippines. It was reported last year that the deaths of approximately 600 children who received the vaccine are under investigation by the Public Attorney's Office. The vaccine has been permanently banned in the country.