In a new fight against Dengue Fever, Brazil has become the first country to roll out a national immunisation program for dengue. More than 5 million doses of the vaccine will be offered to children aged 10-14 years. This comes at the same time Brazil has experienced a major surge in dengue cases.

Over 350,000 cases have been reported in the first 5 weeks of 2024 - more than 4 times the expected number of cases.

Dengue fever cases have increased globally over the past 12 months. Environmental changes due to climate change will see an increase in favourable habitats for the dengue mosquito.

What is dengue fever?

Dengue is a viral disease transmitted to humans by the bite of an aedes mosquito. It is often referred to as “break-bone fever” when there is considerable discomfort in the bones and joints. Dengue can be classified into four types (1,2,3,4). Long-term immunity is possible against any of the serotypes, but this doesn’t protect against the others. In fact, a more serious illness may result.

Where is dengue fever found?

Dengue is found in over 100 countries globally. Unlike the malaria mosquito, the dengue one prefers urban environments. It is a junk yard breeder, preferring to breed in small vessels such as pot plant saucers, empty cans and coconut shells. The mosquito loves rubbish and unfortunately many urban environments are full of rubbish and mosquito friendly.

How is dengue prevented?

You can reduce your risk of dengue by reducing the number of mosquito bites. Everyone will get mosquito bites when travelling but some people are bitten much more than others. These people must pay particular attention to reducing their number of bites.

How long have vaccines been available for dengue?

Dengue vaccines have been around for a few years only. Most countries are just finding their way on how to use these vaccines appropriately. There is always a concern that vaccination might make a future exposure worse.

Two vaccines are currently being discussed. Only one is available in Australia and its use is restricted.

1. Dengvaxia

Dengvaxia first gained regulatory approval in 2015 (3 dose vaccine, spaced 6 months apart). Regulatory approval has been given in a number of countries for its use in dengue endemic countries but restricting its use to the age group 9 to 45 years. It was offered off-licence in Australia in 2019 and has been used in a very limited way ever since. At present is it not available in New Zealand.

The World Health Organisation (WHO) issued a conditional recommendation in 2016 for Dengvaxia use in highly endemic areas, defined by a seroprevalence of 70% and above.

Analysis of the vaccine in 2017 showed there was an increased risk for vaccinated individuals to have an increased risk of developing severe dengue in their first natural dengue infection after vaccination.

In the event of travel to a dengue-endemic or outbreak region, it is advisable to seek medical advice regarding the suitability of the dengue vaccination, this is determined on a case-by-case basis (for individuals who have had the dengue in the past).

2. Qdenga

Qdenga is a live attenuated vaccine. This vaccine is being rolled out in Brazil. It was developed by the Japanese company, Takeda.

It is given in a 2-dose schedule with a 3-month interval. Protection is present from 14 days. The length of protection is yet to be defined but likely more than 4 years.

It is not currently available in Australia (January 2024) but regulatory approval is being sought.

It is available in Europe, UK, Indonesia, Brazil, Argentina and Thailand. It is not available in the USA.

According to WHO’s expert committee on vaccines:

• The vaccine might be considered in settings with a high dengue burden and high transmission to maximise the public health impact.
• It should be introduced to children aged 6 to 16 years.