| Sakina Mohamed |
KUALA LUMPUR (Bernama) – A Malaysian dengue expert is urging the Health Ministry to conduct field testing on the upcoming dengue vaccine amid concerns over its efficacy against certain dengue strains.
Emeritus Professor Datuk Dr Lam Sai Kit, Universiti Malaya’s High Impact Research Consultant, said testing the vaccine in a community setting was different from effi-cacy trials.
“Many new vaccines have undergone such demonstrations or pilot projects to show how the they work in an actual field or community setting, including the people’s acceptance of the vaccine,” said Dr Lam, who has been researching the tropical disease for over 40 years.
Dr Lam, who is also the Immediate Past Chairman of the Asia Pacific Dengue Vaccine to Vaccination Steering Committee said the vaccine should only be made available to the public if its success rate was at 80 per cent and above.
The vaccine manufacturer Sanofi Pas-teur last month announced the outcome of the final stage of clinical studies, and consequently the release of the world’s first dengue vaccine. It is now in the process of production and will be made available in the second half of next year.
The French drug maker said the out-come from the final study on dengue vaccine showed 60.8 per cent overall effi-cacy against the disease. The study was conducted on over 31,000 participants across 10 endemic countries in Latin Ame-rica and Asia, including Malaysia.
The first clinical trials were carried out on 10,275 healthy children aged 2-14 years old in Malaysia, Indonesia, the Philippines, Thailand and Vietnam.
The 25-month surveillance showed an overall efficacy of 56.5 per cent.
However, the data showed good serotype specific protection, with better protection shown against DEN3 and 4 (75 per cent), less protection against DEN1 (50 per cent) and least to DEN2 (35 per cent). It is 88 per cent effective against dengue hemorrhagic fever.
The final clinical trial was conducted on 20,875 children aged 9-16 years old across five countries in Latin America – Brazil, Columbia, Honduras, Mexico and Puerto Rico.
The Latin American trial results indica-ted a 50.3 per cent efficacy against DEN1, 42.3 per cent against DEN2, 74 per cent against DEN3 and 77.7 per cent against DEN4.
However, Health Minister Datuk Seri Dr S Subramaniam had expressed scepticism when reviewing the results of the Asian trial in July as it only showed 35 per cent efficacy against DEN2. The serotype was the most prevalent in Malaysia.
Dr Lam said the percentage of efficacy was not a true reflection of the vaccine’s benefits.
“It is not so much the overall efficacy but the fact that the vaccine can reduce hospi-talisation by 67 per cent and prevented severe dengue by 88.5 per cent which make these results remarkable.
“The results of the Latin American study are consistent with those seen in the Asian trials. In the study, the overall efficacy rate was 60.8 per cent with an 80.3 per cent reduction in risk of hospitalisation and 95.5 per cent reduction of severe dengue. There were also no serious adverse events in both trials,” he said.
A study by the University of Malaya Me-dical Centre in collaboration with Brandeis University in 2012 showed that the eco-nomic burden of dengue in Malaysia was valued at RM360 million per year.
This does not include the cost of vector control, which can be considerable. From January through September 2014, the num-ber of dengue cases reported was 74,335, with 143 deaths.
Dr Lam said if the government’s objective was to reduce hospitalisation and lower the severity of the disease, the demonstration or pilot project should target older children and young adults.
According to the Health Ministry, most dengue deaths occurred among those aged 25-30 in the country.
“The response to the vaccine in older children and young adults should be better since the dengue vaccine works best in those who have pre-existing antibodies to dengue,” said Dr Lam.
He urged the Health Ministry to consider using the vaccine on a pilot study involving a community where dengue was highly endemic.
On the concern Dr Subramaniam had on the lower protection offered to serotype DEN 2 in the clinical trials, Dr Lam said it might not be an issue. Quoting a dengue expert who has served on numerous WHO committees and study groups, Prof Dr Duane Gubler, he said if the objective of the use of the vaccine was to prevent severe dengue then the vaccine is adequate.
“A vaccine which has a public health impact is good enough. We should not wait for a perfect vaccine,” Dr Gubler said.
Echoing the view of Dr Gubler, Dr Lam said the WHO has set the target to reduce the risk of dengue mortality by 50 per cent and reduce morbidity by 25 per cent by 2020.
“I believe the present vaccine has ful-filled the WHO target. We cannot afford to wait since this vaccine will be a welcome addition in our fight against dengue in the country.”