Dengue, everything you need to know about the vaccine

Dengue, everything you need to know about the vaccine

Brazil is experiencing a public health emergency: probable cases of Dengue fever continue to increase and are now close to 2 million – a figure that is four times higher than that reported in the same period of 2023. No alarm, however, for our country : the institutions, as stated by the director of prevention of the Ministry of Health Francesco Vaia and confirmed by a ministerial circular, are initiating prevention protocols to prevent the mosquito vector of the virus that causes the disease from taking root in our territory and are experimenting with tests to identify the virus on a voluntary basis at airports. But what to do if you are planning a trip to Brazil or another country where the disease is endemic? Is it necessary to get vaccinated? Here’s everything you need to know.

What is Dengue Fever Vaccine?

Dengue fever is a particular infectious disease. It is an arbovirosis, i.e. it is caused by a virus (DENV) transmitted through the bite of an animal vector, in the case of Dengue the mosquito Aedes aegypti. Since 2023, we have also had a protective vaccine available in Italy (Qdenga). It is a tetravalent live attenuated virus vaccine, i.e. capable of conferring immunity against the four viral serotypes responsible for the disease. “It is administered in two doses three months apart and, according to the latest available data, completion of the vaccination cycle guarantees long-lasting protection, 4-5 years – he specifies Emanuele Nicastridirector of the High Intensity Treatment Infectious Diseases Unit of the Spallanzani National Institute of Infectious Diseases in Rome – In those who have already had Dengue, among other things, the effectiveness of vaccination is greater than in completely seronegative people, in which the antibody response is lower, especially for serotypes 3 and 4 of the virus.”

Who is vaccination indicated for?

For people who live in Italy and do not plan to travel to countries where Dengue is endemic, that is, roughly all those who are in the band between the two tropics, there is no indication for vaccination. In fact, in our country, on average, a few hundred cases of Dengue are reported per year, almost all of which are imported, i.e. people who show symptoms of the disease upon returning from a trip to tropical areas.

For those traveling to endemic countries, however, some distinctions must be made. “The indication for vaccination against Dengue is strong for those who have already contracted the disease in the past” – explains Nicastri. The first infection, in fact, is asymptomatic or paucisymptomatic in 75-80% of cases, which means that most of the time people do not realize they have had it, while in 20-25% of cases flu-like symptoms may appear, such as fever, headache, muscle and osteoarticular pain and sometimes exanthematous lesions. “When you contract the Dengue virus for the first time you are protected for life from that particular serotype that caused the infection. But if you contract the virus a second time, therefore a different viral serotype, the disease can be more serious: vasculitis develops, i.e. an inflammation of the small arteries which causes a loss of liquids in the interstitial space and consequent effusions of different parts of the body and organ damage. This is why it is important to get vaccinated.” Vaccination, therefore, is also recommended for those who originate from endemic areas and plan to return to their native country, because it is likely that, even if they do not remember it, they have already contracted Dengue in the past. “Furthermore – underlines the expert – the vaccine is also recommended for those who have to travel to areas where the disease is endemic for a long period and who will therefore be exposed to the risk of repeated infections”.

For those who, however, have never been to tropical areas before and will stay there for a short time, there is no strong indication for vaccination. However, people coming from areas where the disease is endemic are recommended to promptly go to the emergency room or traveler’s disease centers if flu-like symptoms appear in the first few days after returning. “The investigations are necessary because in the case of Dengue, the local health authorities must activate disinfestation services to reduce the probability of secondary indigenous cases – specifies Nicastri – Native outbreaks, in fact, have an enormous impact in areas such as the control of blood donations, organs and tissues, which in that case must also be tested for Dengue before being used”.

Who can’t get the vaccine?

Beyond the possible common adverse effects (pain and redness at the injection site, fever, headache, muscle pain, weakness), since the vaccine available for Dengue is a live attenuated virus, its administration is not recommended in pregnant and breastfeeding people and those who are immunocompromised.

When to get the vaccine?

The vaccination cycle involves the administration of two doses three months apart from each other, with the second dose guaranteeing maximum coverage and its duration over time (4-5 years). However, it has been shown that even just one dose of vaccine, administered at least two weeks before departure, provides satisfactory protection, especially for those who have already contracted Dengue in the past. “It is therefore possible to take the first dose of the vaccine before departure and complete the cycle upon return” – confirms Nicastri.

How much does the vaccine cost?

Rates may vary, but indicatively the cost of a dose of Dengue vaccine, which also includes administration, is between 90 and 100 euros in public facilities, while in private it can reach 170 euros.

Where to get the vaccine?

The Dengue fever vaccine has been approved in Italy since 2023. To find out if it is available under a subsidized regime with the National Health Service, it is necessary to contact a Travel Medicine center, present more or less in every local health authority. It can also be found in some private clinics and can be purchased in pharmacies at full price (it can then be administered by a suitably trained healthcare professional, such as a family doctor), but “the ideal would be that people heading towards exotic destinations like those tropical people, book a visit to a specialized clinic well in advance and evaluate, together with your doctor, the possibility of getting vaccinated not only for Dengue, but also for other infectious diseases that you could contract during your stay abroad, for example yellow fever or malaria – advises Nicastri – Counseling is also very useful for evaluating any other risks related to travel, receiving advice and indications on the precautions to follow and on further prophylactic drugs. It should also be underlined that vaccinations carried out at local health authority vaccination centers are recorded in the vaccination registry, which does not always happen in other contexts”.

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