Dengue vaccine has 90% effectiveness against type 2 virus – Expert

• As of July 6, a total of 62422 Dengue patients identified with 39 confirmed deaths

By Sheain Fernandopulle  

Consultant Paediatrician and Founder Clinical Head of the Centre for Clinical Management of Dengue & Dengue Haemorrhagic Fever in Negombo, Dr. Lakkumar Fernando, said an internationally approved dengue vaccine could significantly reduce the burden of the disease as it has more than 90% effectiveness against dengue virus serotype 2 (DENV-2).  

Speaking to the Daily Mirror, Dr. Fernando said he could only comment after clearing any conflict of interest, as he was one of the researchers involved in the development of the vaccine.  

His remarks came after Health Minister Dr. Nalinda Jayatissa announced that the Government is considering introducing an internationally approved dengue vaccine, which is already being used in around 41 countries, while also adopting the scientifically proven Wolbachia mosquito control method.  

“We cannot eradicate dengue with a vaccine. The vaccine is not a complete solution, but it is definitely a way to reduce the burden of dengue in a major way,” Dr. Fernando said. 

He said the TAK-003 (Qdenga) vaccine has demonstrated more than 90% effectiveness against the dengue virus serotype 2 (DENV-2), which is believed to account for around 80% of cases in the current dengue outbreak in Sri Lanka.  

“Sri Lanka has reported all four dengue virus serotypes causing disease, with DENV-2 being the predominant strain. Since the vaccine is highly effective against this strain and also provides protection against the other serotypes, it can significantly reduce the intensity of outbreaks, lower the number of cases and ease pressure on hospitals,” he said.  

Dr. Fernando warned that when hospitals are overwhelmed with dengue patients, not only do dengue-related deaths increase, but patients suffering from other illnesses are also affected.  

He said vaccine costs could vary between the travel vaccine market and the endemic market, adding that the vaccine could provide good protection for tourists visiting Sri Lanka during the current DENV-2-dominated outbreak.  

Although the vaccine is administered in two doses three months apart, he said a single dose would provide sufficient short-term protection to travellers. He also expressed confidence that the Government could negotiate with manufacturers to obtain the vaccine at an affordable price.  

“The first step is to register the vaccine in Sri Lanka and make it available through the private sector. However, I do not think it should be included in the National Immunisation Programme at this stage,” he added.  

Dr. Fernando noted that the vaccine is not new, as its clinical development began nearly two decades ago and extensive studies have established its safety and effectiveness.  

“In its Phase III trial, 20,100 children aged 4–16 years from eight dengue-endemic countries in Asia and Latin America received the vaccine in a 2:1 ratio in a double-blind, placebo-controlled trial,” he explained.  

Sri Lanka participated in a Phase III clinical trial of Takeda’s TAK-003 vaccine during the country’s worst dengue outbreak in 2017, when 186,101 cases and 440 deaths were reported. The trial, involving 2,100 children and adolescents in Colombo and Gampaha, found that the vaccine reduced virologically confirmed dengue cases by 94.7% and dengue-related hospitalisations by 95.7%.  

A follow-up study conducted around 4.5 years later found that the vaccine continued to provide 84.4% protection against dengue infections and 87.9% protection against dengue-related hospitalisations.  

Researchers also found that a vaccination campaign covering around 65% of the target population could reduce dengue cases by about 69% and hospitalisations by around 73%.  

The TAK-003 (Qdenga) vaccine has been approved in more than 40 countries, including Indonesia, Thailand, Brazil and Argentina. However, Sri Lanka has yet to introduce a dengue vaccine into its National Immunisation Programme.