Photo by: Reuters

A patient lies on a bed in a ward reserved for people suffering from dengue fever in a hospital at Barrio Obrero district in Asuncion, Paraguay on April 14. The mosquito-borne disease is a threat to nearly half of the world’s population. Four people have died from the disease in Cambodia so far this year.

Health experts have announced that a dengue vaccine could be available within four years, sparking concerns about future supply for populations in developing countries at most risk of contracting the mosquito-borne virus.

According to an article published by the United Nations IRIN news service, experts said that pending the results of ongoing clinical trials, dengue immunisation could begin as early as 2015.

Luiz Jacintho da Silva, director of the South Korea-based International Vaccine Institute, told IRIN that vaccine developer Sanofi Pasteur was making progress on the dengue vaccine.

“Unless someone pops up with something fantastic, they will be the sole producer for a few years,” Da Silva said.

“Capacity will be limited and we will not be able to reach everyone.”

Dr Steven Bjorge, director of Malaria, Vector-borne and Parasitic Diseases at the World Health Organisation in Cambodia, said yesterday that there were significant hurdles in producing the vaccine.

“There are four dengue viruses,” Bjorge said.

“[One] thing will be whether it is efficient to have just one vaccine or if it requires two or three to achieve full immunity,” he said.

Bjorge added that some people who have severe reactions to dengue have experienced an earlier infection from a different virus.

“The concern is whether or not vaccination itself will induce that adverse effect,” he said.

Ngan Chantha, director of the National Anti-Dengue programme at the Ministry of Health, said that the vaccine had been on trial in Thailand and Vietnam.

“So far, there is no drug to cure the disease and no vaccine but we can prevent dengue through encouraging ... parents to take responsibility for themselves and to take care of their children by cleaning the environment around their house [to prevent mosquitos from breeding],” he said.

Dr Bjorge said that a dengue vaccine was unlikely to be cheap but many would be anxious for immunisation.

“Right now we’re left with vector control, cleaning up breeding sites that mosquitos are using around the house,” he said. “These things require regular maintenance and it’s proven to be difficult.”

“If the vaccine is in a range of 80 to 90 percent effective ... donors will be willing to carry some of the [financial] burden.”

Ngan Chantha said from January 1 to April 13 there had been 339 recorded cases of dengue fever in Cambodia resulting in four deaths, compared with 482 cases resulting in three deaths over the same period last year.