After decades of research, the World Health Organization endorsed earlier this year the first vaccine against dengue, a virus that infects about 390 million people in the world every year and has no known treatment. Now the vaccine faces its next challenge: adoption.
In the heavily affected region of Southeast Asia, the Philippines was the first to launch a public dengue immunization program and several countries are looking with interest at the new vaccine, according to experts attending ASEAN Dengue Day in Bangkok on June 15.
“We have to be very careful with the approval process because there will be a lot of questions [being raised], on topics such as effectiveness”, says Amnuay Gajeena, director- general of the Department of Disease Control at the Thai Ministry of Public Health during the celebration of the Sixth ASEAN Dengue Day that this year was hosted by Thailand.
“[In Thailand] it is still in the process of being put in the agenda but we haven’t made any decision yet…”
In December last year, Mexico became the first country in the world to license Dengvaxia, the dengue vaccine developed by French-based Sanofi Pasteur. Three more countries, namely Brazil, El Salvador and The Philippines, have followed since.
“[In Thailand] it is still in the process of being put in the agenda but we haven’t made any decision yet,” says Dr. Gajeena. According to his department, it normally takes years to include any vaccine in the National Expanded Programme on Immunization (EPI) that today administers 10 vaccines to Thai children. The government could nevertheless approve the vaccine to be sold at private hospitals in the coming months.
During its development, a clinical trial was run in 10 countries – five in Asia and five in Latin America but the widespread vaccination campaign earlier this year. “It is a brand new vaccine. It has not yet been widely used except in a few countries, like in the Philippines’ public immunization drive. Therefore it is natural that some governments hesitate when it comes to adoption,” says Dr. Tikki Pang, visiting Professor of the Lee Kuan Yew School of Public Policy. Dr. Pang highlights effectiveness, but also cost and safety concerns as the main barriers for the administration of the vaccine. “Other governments, e.g. Singapore, have also invested heavily in other tools such as mosquito control and public education/awareness”, says the expert.
The approval of new dengue vaccines could also make the process of adoption into the National Immunization Plans lengthier. According to the World Health Organization, there are at least five additional dengue vaccine candidates in clinical development, with two of them (developed by Butantan and Takeda) expected to begin Phase III trials in early 2016. ”
In this scenario, each country will choose the vaccine that will work best in their own setting, based on the public health authorities’ assessment of public health needs, country capacities, and available cost-effectiveness, safety and efficacy data” says Dr. Pang.
Local communities, key in adopting the dengue vaccine
Governments may not be the only ones slow to embrace the vaccine. “Both government and populations will be difficult to convince but perhaps for different reasons. […] Individuals in the population will have to be convinced of its safety and ability to prevent disease”, says Dr. Tang.
“Education and communication are very important. You need to give them the right information and tell them that it is not 100% effective but there is efficacy there,” adds Usa Thisyakorn, chairman of the Asian Dengue Vaccination Advocacy (ADVA), a scientific working group dedicated to disseminating information and making recommendations on dengue vaccine introduction strategies in Asia.
Discover the public health value of dengue vaccination
The first public dengue immunization program launched last March in The Philippines, where about 1 million children will be vaccinated this year, will likely be a reference for its neighbors in Southeast Asia, one of the regions in the world most heavily affected by dengue fever. Last year, when large dengue outbreaks were reported worldwide, the Philippines registered more than 169,000 cases and Malaysia exceeded 111,000 suspected cases of dengue, representing a 59.5% and 16% increase, respectively, compared to the previous year, according to WHO.
Nevertheless, even though the vaccine is an important step forward in the fight against dengue, vector control remains one of the main strategies to eradicate the disease. And, as stressed by this year’s ASEAN Dengue Day theme, ‘Community Empowerment: A Sustainable Success to Fight Dengue’, communities are the key to containing the spread of the virus.
“This is a vector-borne disease. The vector, the Aedes aegypti, is a house mosquito, so the problem starts from the environment and it should be addressed by the residents of the communities,” says Dr. Amnuay Gajeena. Dr. Gajeena explains that the Thai government follows the ‘Triple K’ strategy for vector-borne control asking villagers to keep containers closed or empty of water; keep the house clean, and keep trash in its proper place.
Understanding the knowledge that local populations have related to the disease is also important to designing better strategies. With this aim, the Asian Dengue Vaccination Advocacy group has launched this year the Dengue Mission Buzz Barometer, a tool to measure engagement of communities throughout Southeast Asia in dengue prevention.
“They need to understand that vector is everywhere and if you don’t participate in vector control it is going to be a disaster,” says Dr. Usa Thisyakorn, who stresses that dengue is a global problem. “People now travel a lot so the disease can go everywhere in the world.”
Learn more on the lasting affects dengue has on people’s lives in our short documentary.
Watch, ‘The Lingering Effect of Dengue Fever’