With dengue cases on the rise in Singapore this year, threatening to break the record 22,000 infections in 2013, readers have asked why a dengue vaccine is not yet available here. Senior Health Correspondent Salma Khalik explains.

There is currently only one dengue vaccine that is commercially available in the world.

But it is not yet available here.

This vaccine by Sanofi Pasteur is not a good fit for the situation in Singapore as it offers best protection against the two strains that are not so commonly found here.

However, it has been shown to be effective in reducing the seriousness of the illness once someone is infected with dengue, regardless of the dengue strain (there are four strains of dengue virus). This vaccine is currently available only in a few countries, such as Brazil and the Philippines. The company needs to have the vaccine approved by the Health Sciences Authority before it can be brought in for use here.

At least two more vaccines, expected to hit the markets in the coming years, appear more appropriate to conditions here.

In clinical trials, none of the vaccines can guarantee no infection.

What they do is to reduce the risk of getting infected, and reduce the severity of illness when a person does get infected.

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