As the world watches the horrifying spread of the Ebola virus across West Africa, there is some good news from Southeast Asia in regards to another potentially fatal disease -- dengue fever.

 

On July 11, French drugmaker Sanofi announced in The Lancet, a medical journal, that its dengue vaccine had passed phase III clinical trials in Southeast Asia, one of the last stages of tests for a drug before it can be put on the market. 

 

Until now, there has been no way to prevent the mosquito-borne disease. Southeast Asia is home to most of the world's 100 million to 200 million dengue infections reported each year. This year has been particularly bad in Malaysia, where 110 people have died and over 56,810 cases have been recorded as of Aug. 2, two-and-a-half times the number from this time last year. In Singapore, a "high-risk dengue cluster" was identified on the campus of National University of Singapore this month.

 

Symptoms of the disease include high fever, headache, pain behind the eyes and joint and muscular pain. If left untreated, the fatality rate for severe dengue fever is as high as 20%, according to the World Health Organization.

 

Hesitant relief

Officials involved in the fight against the disease are not celebrating just yet. They now face a dilemma over whether the benefits of the first dengue vaccine, which went through trials in Indonesia, Malaysia, Philippines, Thailand and Vietnam, outweigh the risks. The vaccine, which could be marketed as early as the middle of next year, has not worked on all of the 6,851 children who received it during the trial, with 117 of those vaccinated still developing dengue fever. This was around half the infection rate of a control group that was given a placebo, but not enough to convince some health officials in Asia.

 

The vaccine, called the CYD dengue vaccine, also showed unequal protection against the four dengue virus strains, with stronger protection shown against the DEN-3 and DEN-4 strains, moderate protection against DEN-1 and weaker protection against DEN-2. This has raised concern among scientists that the vaccine could affect a recipient's immune system, making it more at risk to the strains that are less protected. This, they fear, could lead to more cases of fatal dengue hemorrhagic fever. 

 

Still, dengue researchers say these fears may have overshadowed other important findings -- a 67.2% reduction in cases that need hospital treatment and an 88.5% reduction of dengue hemorrhagic fever after three doses of the vaccine.

 

Dr. S. Subramaniam, Malaysia's health minister, this month said the lower protection against the DEN-2 strain was "not satisfactory," but did not rule out using the treatment after further study of the trial data. Dr. Vivian Balakrishnan, Singapore's environment and water resources minister, told his country's parliament that the vaccine was "not good enough," citing the lower effectiveness of the vaccine against the DEN-1 and DEN-2, which are the most common strains in Singapore. Health authorities in the Philippines and Thailand have been more positive about introducing the CYD vaccine, but are still uncommitted to adopting it on a large scale.

 

The best for now

While the world awaits the results of the CYD vaccine's complementary phase III trial in Latin America, supporters of the vaccine are trying to convince health officials in Asia that it should be seen as a means to reduce dengue deaths instead of preventing dengue altogether.

 

According to Dr. Lam Sai Kit, a virologist at the University of Malaya who has been involved in dengue research for over 40 years, the data from the trial so far has been a "good enough" reason to consider introducing the vaccine in affected countries, as it could reduce health care costs and prevent immense suffering and deaths. A 2012 study by the University Malaya Medical Center and Brandeis University in the U.S. estimated the economic burden of dengue in Malaysia to be $102 million per year, exclusive of dengue control and indirect socioeconomic costs.

 

Some researchers are also telling policymakers that they cannot afford to wait for drugmakers to come up with a better treatment. Rival vaccines being developed by Brazil's Butantan Institute, Japan's Takeda Pharmaceutical, Merck in the U.S. and the National Institutes of Health are still years away from phase III trials. Professor Annelies Wilder-Smith, an infectious disease researcher at Singapore's Nanyang Technological University, said the vaccine was still the only likely option available in the absence of an effective program to control the Aedes mosquito, the carrier of the dengue virus.

 

There is always the question of cost, however. At the moment, Sanofi has not released the price for the vaccine. Nevertheless, the company has promised to price it "responsibly." Governments may also be able to get funding from organizations such as the Bill & Melinda Gates Foundation, which funds the Pediatric Dengue Vaccine Initiative.

 

LIM WEY WEN,

Contributing writer, asia.nikkei