Another week, another milestone. Momentum is building for the widespread use of the first-ever dengue vaccine.

Last week saw the launch of a dengue vaccine program in Paraná State in Brazil, while private clinics in El Salvador began offing vaccination to clients.

This week public health officials are poring over the World Health Organisation’s first ever position paper on a dengue vaccine.

With a vaccination program well under way the Philippines, several Asia countries considering adding the vaccine to their schedules and Mexico inching towards rolling out a dengue program, the second half of 2016 is shaping up to be a momentous chapter in the fight against the disease.

3.2 million severe cases

The paper supports the recommendation by the WHO’s immunization expert group (SAGE) published in April and sets out clear recommendations for governments around the world.

The WHO says dengue is responsible for around 3.2 million cases of severe illness and 9,000 deaths, mostly in lower-middle income countries. This translates into a loss of 1.1 million disability adjusted life years.

The need for action is plain.

“Countries should consider the introduction of the dengue vaccine only in geographic settings (national or subnational) where epidemiological data indicate a high burden of disease,” the paper states.

The vaccine should be introduced along with a strong communication campaign and as part of an integrated approach to dengue control that includes vector control and disease surveillance.

“Dengue vaccine introduction should be a part of a comprehensive dengue control strategy, including well-executed and sustained vector control, evidence-based best practices for clinical care for all patients with dengue illness, and strong dengue surveillance,” according to the WHO.

Choosing target age groups

It sets out advice on how to select which age groups to target with vaccination, taking into account a combination of seroprevalence, disease surveillance data, and local factors.

“Some countries may experience the highest incidence of dengue illness among adults and may consider vaccinating populations up to 45 years of age in routine programs,” the WHO says.

This broadly chimes with the strategy adopted by Paraná where people aged 15 to 27 will be targeted in 28 municipalities, while the target group ranges from 9 to 44 years in two additional areas with the highest incidence.

“The selection of the municipalities was based on the disease epidemiology in Paraná,” Michele Caputo Neto, Paraná Health Secretary, told Break Dengue. “The municipalities that suffered three epidemics or more in the last five periods, between 2010 and 2015 were taken into consideration.” Hospitalization for serious dengue was also a factor, according to health officials in the Brazilian state.

Clearing logistical hurdles

The WHO position paper answers a range of practical questions health officials may have had regarding how to run an immunization program.

For example, it states that should a vaccine dose be delayed for any reason, the vaccine course should be resumed rather than restarted, maintaining a six-month interval between subsequent doses.

The challenge of fitting the new vaccine into existing vaccine schedules is also tackled with a particular emphasis on the practicalities of giving the dengue vaccine at the same time as other immunizations.

“Because the risk of immunological interference due to co-administration of live with non-live vaccines is considered small, co-administration is permissible with these and other non-live attenuated vaccines,” according to the WHO paper. “Co-administration may be desirable to reduce programmatic costs associated with school-based vaccination programs.”

In short, the dengue jab can be incorporated into existing vaccine programs without any major problem. Indeed, where school-based vaccination systems are already in place, it may save money to add the dengue vaccine to the schedule.

Now, what?

The WHO position paper is a major landmark in the dengue vaccine story. With health officials in Asia and Latin America currently exploring when and how to introduce the vaccine, this may be the tipping point for improving public health and the dengue vaccine’s widespread adoption.

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