Sanofi Pasteur, the  vaccines  division  of  Sanofi, has announced clinical  study results showing the ability of its vaccine candidate to protect against dengue fever caused by three  dengue virus types. The results of the world’s first efficacy study confirm the excellent safety profile of Sanofi Pasteur’s dengue vaccine candidate.

A feature of dengue epidemiology is that the relative prevalence of virus types in a given area is evolving  with time. Large-scale phase III clinical studies of Sanofi Pasteur’s dengue vaccine candidate are underway with 31,000 children and adolescents in 10 countries in Asia and Latin America. These studies will generate important additional data in a broader population and in a variety of epidemiological settings to define the best conditions to set up vaccination programs in order to protect people at risk of dengue.

The study was conducted in 4,002 children aged 4 to 11 years, in partnership with the Mahidol University under the patronage of the Thai Ministry of Public Health in Muang district of the Ratchaburi Province. Sanofi Pasteur's dengue vaccine candidate is a live, attenuated vaccine. The vaccination schedule is 3 doses given 6 months apart (at 0, 6 and 12 months).

Dr. Scott Halstead, International Vaccine Institute, Seoul, Republic of Korea., said, “The complexity of dengue virus infection has hampered vaccine research for decades. This is the first time in 50 years of dengue research that I have seen a vaccine that protected a large group of children from  clinical disease caused by dengue viruses. Best yet, the vaccine met the highest safety expectations. These results should be a source of hope for millions of parents whose children are at risk of severe dengue, a life-threatening disease which often requires hospitalization.”

The full analysis of vaccine efficacy against each serotype, reflecting real-life conditions (intent to treat  analysis) showed vaccine efficacy to be 61.2 per cent against dengue virus type 1, 81.9 per cent against type 3 and 90 per cent against type 4. One of the dengue virus types (serotype 2) eluded the vaccine. Analyses  are  ongoing  to  understand  the  lack  of  protection  for  serotype 2  in  the  particular epidemiological context of Thailand.

“Having worked in the field of dengue research for over four decades, with much of my efforts focused on prevention and control, it is very exciting for me to see a safe vaccine candidate that provides protection against 3 of the four dengue serotypes,” said Professor Duane Gubler, Program on Emerging Infectious Diseases, Duke-NSU Graduate Medical School, Singapore. “Dengue is a major public health  concern for over half of the world’s population and is a leading cause of hospitalization and death  among children in endemic countries.  Because mosquito control has failed to control this disease, an effective vaccine will be a critical tool that can change the life of millions living in endemic countries. I see this success as the beginning of a new era of effective control.”

According to Dr. Roberto Tapia Conyer, General Director of the Carlos Slim Health Institute, Former Undersecretary of Health in Mexico, “These dengue vaccine results bring a significant promise in the  context of  the  expanding  dengue  disease burden worldwide and the  absence of  specific treatment. Work will continue to study this vaccine and the circulation of dengue viruses globally, but in the meantime, the public health community can now formulate the best possible immunization policies and prepare for implementation of vaccination campaigns in countries heavily affected by dengue.”