- by Alison Booth

What are the benefits of dengue vaccination?

Image of an Aedes mosquito covered by a text reading 'What are the benefits of dengue vaccination?'

Life is full of decisions. But no decision is ever black or white. Each has an upside and a downside. Every health decision – medical treatment, surgery and preventative measure – has its benefits and its risk. We spoke with Professor Tikki Pang (Pangestu), Visiting Professor at the Lee Kuan Yew School of Public Policy in the National University of Singapore, about weighing up the cost and benefits of dengue vaccination.

Dengue vaccination is around 66% effective at protecting against the disease when used in appropriate populations, according to Professor Pang. While you may think this is low, the public health and economic benefits these levels of protection deliver can be considerable.

Professor Pang uses Malaysia, which has about 100,000 dengue cases each year, as an example: “The cost savings from protecting 66,000 people can be very, very significant. Fewer people need to be cared for in hospital.”

The benefit also extends to specific industries. “A country suffering from an epidemic of dengue will see a drop in the number of tourists visiting,” says Professor Pang. “The vaccine can alleviate that loss of income.”

The real benefits of dengue vaccination

The vaccine also benefits individuals, giving “an enhanced sense of security and safety,” according to the Professor. He adds: “The protection means you don’t need to take any time off work, which is particularly important for people who don’t have paid medical leave.”

Professor Pang speaks from experience. “When I had dengue, it knocked me out for about two weeks. I couldn’t function,” he says.

And if someone is not infected, their immediate family will also be less at risk of getting sick. The actual benefit of dengue vaccination is, therefore, in reality, much greater than its 66% efficiency would suggest.

Read more about uncovering the hidden economic cost of dengue

“Dengue vaccination cuts the total number of people likely to get infected,” says Professor Pang. “Researchers have modeled the tremendous impact vaccination has on reducing the overall number of cases.”

A sensitive balance

Professor Pang was keen to highlight that while “no new drug is completely free of risks”, the dengue vaccine had been studied on 30,000 people in 10 countries. This research, he said, found the dengue vaccine only caused minor side-effects such as a rash, slight fever or some pain at the injection site, adding “There are no very serious risks such as bleeding or going into shock.”

When it comes to deciding whether to adopt the dengue vaccine, countries must analyze the benefits and weigh them against the costs. “It can be a sensitive subject because it’s balancing the risk to the individual against the benefit of protecting the whole population,” says Professor Pang. “Research has shown the dengue vaccine is very cost effective in terms of how much it will cost and how much benefit it will bring populations receiving it”.

He is referring to the wealth of research on the topic. “Modelling studies have shown dengue vaccination to be both effective in reducing the number of people who get sick and cutting healthcare costs,” says Professor Pang.

Opposing views

The government in the Philippines suspended its dengue vaccine program following the dengue vaccine scare in the country. This followed concerns related to vaccinating people who had never before been infected with any dengue virus. Professor Pang believes the decision to scrap dengue immunization is “really unwarranted”.

“Only a very small percentage of the population – around 1% of children not previously exposed to dengue – got a little bit of the severe form of the disease,” says Professor Pang, who believes there were no deaths as a result of the vaccine. “It was nothing serious and well managed. All the children recovered well.”

The media did not agree with headlines stating that children had died because of the dengue vaccine. The Professor believes these headlines were “utter nonsense”. He is convinced the reported deaths had nothing to do with the vaccine; rather the children had other serious diseases that were not known when they received their vaccinations.

In fact, he is frustrated with the media for “sensationalizing the issue” but, at the same time, acknowledges the situation is quite complicated with lots of domestic political factors at play.

Brazil, meanwhile, is continuing with its vaccine program. With one million cases of dengue a year, even just 60% vaccine effectiveness means 600,000 people are protected. “Brazil has very good risk communication and a very responsible media,” says Professor Pang.

‘Point of care’ tests

Recent World Health Organization recommendations suggest using the vaccine “when a point of care test becomes available” and “in areas where there is a very high level of dengue”.

The Professor is concerned that point of care testing may not be feasible in some countries because it is impractical, more specifically time-consuming and very expensive.

His ideal scenario would be to have a very easy-to-use, fast, cost-efficient and reliable point of care test that uses a finger prick, costs one US dollar and where results are within an hour or 30 minutes.

“We are far from that situation,” says Professor Pang. He explains that before even giving the vaccine, you have to withdraw blood from children, which is not trivial. The wait for the test results could then be as much as a week. After that, the children would need to come back for three more injections.

Endemic dengue

Professor Pang says the recommendation for using the vaccine in areas where dengue levels are high “makes perfect sense”. He comments that the WHO recommendation has always been to consider the dengue vaccine in areas where the percentage of people who have already had dengue is greater than 70%.

“In Philippines, Indonesia, Thailand, and Malaysia, 90% of the population would have been exposed to dengue by the age of 15,” says Professor Pang. “At the age of nine, it’s probably closer to 70 or 80%.”

Singapore, notes Professor Pang, is an exception. With the virus not circulating at such high levels, he agrees the dengue vaccine is not justified but believes it may still be useful for travelers going from Singapore to Indonesia or the Philippines, for instance – particularly if they have young children.

Improving communication

Professor Pang suggested some potential actions he believes would help. The first is improving risk communication, awareness, and education around the current vaccine. “You need to communicate the issue of risk very clearly, to explain it’s much riskier for your kid to get dengue than the vaccine.”

The second is managing the expectations of countries waiting for newer dengue fever vaccine pipeline products. Professor Pang believes it will be at least another two or three years before another vaccine is ready. “The studies are still ongoing,” he says. “They have to analyze their data, publish their results in an independently reviewed journal and then they have to submit their dengue vaccine for regulatory approval.”

He also feels these potential dengue vaccines are actually quite similar to the currently available vaccine: “There’s nothing particularly different or revolutionary about these two new vaccines.”

To conclude, Professor Pang shared his advice for governments – many of whom he sees as “sitting on the fence” when it comes to using the vaccine for public health issues. He suggests they should follow the example of Brazil: “The Brazilians adopted the dengue vaccine because they understood the magnitude of the public health problem”.

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