Letters

Tuesday, 19 January 2016

Dengue vaccine – why wait?

YOUR front page report on the increased incidence of dengue fever cases is timely, “1 patient every 3 minutes” (The Star, Jan 12). Although it highlighted the overwhelming increase in cases and deaths, it also talked about preventive steps to reduce the vector, the Aedes aegypti mosquito.

As we all know, vector control as is practised in many Asian countries over the last few decades has not reduced the disease burden nor the mosquito population.

With success in the initial phases, there is no sustainable reduction in the vector population and it cannot be claimed to have been a success. The stress on community involvement and buy-in has fallen on deaf ears, despite punitive action.

Proper case management has resulted in low death rates from dengue infection. Monitoring and surveillance has led to better reporting of the disease, more widespread public knowledge and early treatment-seeking behaviour. Although these have led to earlier institution of treatment and better survival, they have not reduced the number of cases.

The much-anticipated dengue vaccine that took 20 years and US$1.5bil to develop is now available. Having been tested on more than 40,000 subjects in 15 countries, Malaysia included, it has only been licensed in three countries in December 2015 – Mexico, the Philippines and Brazil.

This is the first vaccine developed with the intention of using in the developed world for an endemic disease instead of a first world vaccine being passed down to us with US Food and Drug Administration (FDA) and European Medicines Agency (EMA) approvals, and WHO pre-qualification.

Despite all this, we are hesitating to license the vaccine. The Health Minister has mentioned the low vaccine efficacy and age groups involved.

In summary, the vaccine works better for individuals aged nine to 45 years, and on those who had been primed to the disease, i.e. those who had a previous infection or exposure. Out of the four dengue virus serotypes, the vaccine has shown low efficacy against serotype 2. It has significantly reduced the incidence of severe dengue infection and hospital admissions. Safety issues have been alluded to in the published studies.

After waiting for so long, many paediatricians and other doctors who have been following the development of the dengue vaccine are eager to use it. Hopefully, Malaysia will be the fourth country in the world and second in Asia to license the vaccine.

As with any other vaccine introduction in the country, the private sector will be using it first. With this particular vaccine, the tracking of adverse events has to be more stringent over the next few years to detect other complications that may have been missed in the efficacy trials. Real world effectiveness of any vaccine follows post-licensure surveillance of disease, hospital admissions and adverse events.

We should not be deluded into abandoning vector control just because we have the vaccine. The control of breeding of the Aedes aegypti mosquito has to continue as it is also the vector for chikungunya, yellow fever, and the Zika virus that has been linked to babies born with brain defects in Brazil.

We do not have to wait for the perfect vaccine with more than 90% efficacy before we protect our population from dengue. We should be using the vaccine with the above caveats on continued vector control and other strategies.

DATUK DR ZULKIFLI ISMAIL

President

Asia Pacific Pediatric Association

Tags / Keywords: Letters , Health , Dengue Vaccine

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