Clinical Trials for Sanofi Dengue Vaccine

Mr Christopher de Souza asked the Minister for Health (a) whether there are clinical trial runs for the Sanofi dengue vaccine being conducted in Singapore; (b) whether an approved dengue vaccine can be used to help reduce the number of people who suffer from dengue fever in Singapore; and (c) whether the Ministry has plans to eventually make a dengue vaccine available under the National Childhood Immunisation Programme (NCIP), just like the polio vaccine.

The Parliamentary Secretary to the Minister for Health (Assoc Prof Dr Muhammad Faishal Ibrahim) (for the Minister for Health): Mdm Speaker, a Phase II clinical trial for the Sanofi dengue vaccine has been conducted among 1,200 patients in Singapore. It aims to assess the immune response and safety of the vaccine in healthy persons aged two to 45 years old. The study started in 2009 and follow-up of persons in the study is still on-going at our public hospitals.

A dengue vaccine could potentially help reduce the number of cases of dengue in Singapore. However, it is too early to definitively assess the effects of the Sanofi dengue vaccine. As with all new vaccines, it must first be scientifically assessed by the Health Sciences Authority (HSA) for its safety, quality and efficacy to meet internationally benchmarked standards, before the vaccine is approved for use in Singapore. In granting marketing approval, HSA will take into account whether the data provided from the clinical trial studies demonstrates that the benefits of the vaccine outweigh the risks of potential

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side effects, if any.

Results from two large scale Phase III studies, conducted in Asia and South America, were reported recently. Both studies focused on effectiveness of the vaccine in children, whereas in Singapore, most dengue cases occur in adults. The results were similar and showed lower efficacy against dengue virus serotypes 1 and 2, which are the commonest types circulating in Singapore. There had previously been reports that while past infection with one serotype confers immunity and protection against that serotype, it could lead to more serious disease if infection with a different serotype occurs.

More study is needed to ascertain whether similarly, incomplete protection from vaccination could potentially result in the risk of more severe infection from serotypes which the vaccine protects poorly against. To reduce the number of dengue cases, other measures such as reducing the number of mosquito breeding sites and using mosquito repellents continue to play an important part.

An Expert Committee on Immunisation (ECI) advises MOH on matters related to vaccination. The ECI considers factors such as the local burden of disease, vaccine safety, efficacy and cost-effectiveness when recommending whether a particular vaccine, such as the dengue vaccine when it becomes available, should be included into the National Childhood Immunisation Schedule.