When an effective vaccine for dengue fever finally hits the market, endemic countries in the developing world may be the first to benefit because, unusually, health experts are preparing for roll-out now even though the vaccine will not be ready for several years.
"In the past, when new vaccines were developed, it took years for them to reach people in developing countries on a large scale," says Joachim Hombach, acting head of the WHO's Initiative for Vaccine Research. "A future dengue vaccine would try to repeat what has been done with vaccines for rotavirus and pneumococcal disease, when the time it took between licensing and introduction of the vaccine in developing countries was massively reduced.
The drug company Sanofi-Pasteur — which has 12 sites, one of which is in France — is trialling a dengue vaccine in Australia and wants the vaccine to go straight to endemic countries.
"The goal is to make the dengue vaccine available as early as 2015," Michael Watson, vice president of global immunisation policy at Sanofi-Pasteur, tells the Bulletin of the World Health Organisation. "The time between now and when the vaccine will be available is actually very, very short and there is an awful lot to do."
"We cannot wait for the vaccine to be available, we have to do work now," says Luiz Jacintho da Silva, director of the Dengue Vaccine Initiative, a consortium of four organisations.
Top of the list are the needs for improved disease surveillance and for the epidemiological data that Sanofi-Pasteur and its partners need to make decisions on who should receive the vaccine first.
"Available epidemiological data, with few exceptions, are inadequate," says da Silva. "They are barely sufficient to make educated guesses on vaccination policies."
There are also regulatory issues, which vary from country to country, to deal with, as well as the financial constraints on low-income countries.
Once the vaccine is available demand is likely to be high. But it is likely to be scrutinised for its cost-efficacy — although the disease causes an economic burden, it is not as deadly as malaria and HIV/AIDS, which means the public health community ranks it lower in terms of importance.
The estimated incidence of the disease has increased 30-fold over the past 50 years with 50 million dengue infections now occurring worldwide each year.