Dengue Vaccine: Prospects

The concept of dengue vaccine is recommended by WHO in order to prevent the infection of dengue in the tropical areas as the disease is highly common in these areas. The developing process of the vaccine started as early as 1929. However, it has been hindered due to having incomplete knowledge of the disease pathogenesis. Later the need of creating a stable immunity against all four dengue serotypes simultaneously further affected the process. Experiments have been conducted to develop the vaccines with different formulations including live attenuated, inactivated, DNA and subunit vaccines in order to get the most efficient one. In 2016, the first partially effective vaccine for dengue fever named Dengvaxia became commercially available in 11 countries, namely, Mexico, the Philippines, Indonesia, Brazil, El Salvador, Costa Rica, Paragua, Guatemala, Peru, Thailand, and Singapore. The costing was recorded to be around US$207 for the three recommended doses of the vaccine in Indonesia. During that period, WHO recommended limiting the use of the vaccine in the areas where the disease is common because there were chances of increasing the risk of dengue fever in people who have not been previously infected with the dengue virus through vaccination. This led to the phenomenon of antibody-dependent enhancement.

Vaccine Development:

Dengvaxia (CYD-TDV) developed by Sanofi Pasteur, was first registered in Mexico which is a live recombinant tetravalent dengue vaccine (in order to give protection from all four serotypes) which was evaluated as a 3-dose series on a 0/6/12 month schedule in Phase III clinical studies. It has been registered for use in individuals 9-45 years of age living in endemic areas. Further, the phase III trials in Latin America and Asia involving over 31,000 children between the ages of 2 and 14 years indicated vaccine efficacy is dependent on the serotypes but a report of 56.5% efficacy in the Asian study and 64.7% efficacy in the Latin American study was observed. Both the trials showed a reduction of about 80% of the severe dengue cases. Further analysis of both studies at the 3rd year of follow-up showed an efficacy of 65.6% in preventing hospitalization in children older than 9 years of age.

Vaccine Approval

In December 2015, the vaccine was approved in Mexico, Philippines, and Brazil. Then in 2016, El Salvador, Costa Rica, Paraguay, Guatemala, Peru, Indonesia, Thailand and Singapore approved it. 

Prospect of Dengue Vaccine

According to the National Vector Borne Disease Control Programme (NVBDCP) 18 out of 35 states of India are now endemic for dengue and the spread of the disease to suburban and rural areas are still continuing. However, there is a reduction in dengue-associated mortality and hospitalization rates. Dengue vaccines can serve as a cost-effective preventive strategy in controlling the infection.

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