Dengue vaccine for travelers/foreigners in Thailand: Should I get it?

Right now dengue vaccine has been registered and available in some hospitals in Thailand, including ours. Some travelers did ask us whether they should get dengue vaccine or not and what is our recommendation. 

In fact, to answer this question is not easy as it seems. 

For those who prefer a quick answer without any detail. Our answer is no. We DO NOT recommend the use of dengue vaccine in travelers visiting Thailand. For those who live/work in Thailand (the expat), we also do not recommend. Currently, we will give dengue vaccine only to local people who live here. If you are an expat, you have to live here in Thailand (or in the tropics) at least 9 years in order to get the vaccine. 

What is the reason behind? Why don’t we recommend to use in travelers? Why do you need to live here for 9 years before we will give the vaccine. We will try to answer and explain as simple as possible. However, some basic knowledge is required in order to understand. It is recommended to read these articles first if you haven’t already. 

 

Here are some important information about dengue infection and dengue vaccine:

1. Dengue virus that cause dengue infection has 4 different serotypes namely Dengue 1,2,3,4  (DEN1, DEN2, DEN3, DEN4). If you get infected with DEN1, you will have life-long immunity against DEN1. However, you may have a chance to get DEN2, 3, 4 later in your life.

2. Scientists believe when people get primary (1st time) infection with dengue virus, the disease is usually mild and self limited. However, if that patient get dengue infection again (secondary infection), there is an increase risk to develop more severe disease. However, it doesn’t mean that all patients with secondary dengue infection will be severe. In fact, the majority of the cases is still mild, but chance to develop severe disease is higher than primary infection. 

Ades mosquito that transmitted dengue virus

3. So ideal dengue vaccine should create life long immunity against all four serotypes of dengue virus. If we have that kind of vaccine, that’s fantastic. Unfortunately, we do not live in an ideal world.

4. The only available vaccine that we have today is call Dengvaxia®. It is a live attenuated dengue vaccine contains all four serotypes of dengue virus. In term of safety, it is excellent. There is no safety concern of this vaccine i.e. the side effect is usually mild, no serious side-effect ever reported from the vaccine.  However given dengue vaccine is a lived vaccine; it is not contraindicated to use in certain persons such as pregnant/breast feeding woman, immunocompromised person, people who use corticosteroid, who has cancer.

5. However, when talking about the efficacy, it is not excellent. The overall efficacy of vaccine against all serotypes of dengue virus was around 65%. That means even you get the vaccine you still have a chance to get dengue infection, it could actually reduce to risk approximately 65% When researchers looked into detail, they found that the efficacy against DEN3, DEN4 was very good when compared to dengue DEN1, DEN2

5. Before the vaccine is commercially available, it has been used in more than 30,000 healthy volunteers mostly were in children. Researchers found that younger children (age less than 9 years) responded poorly to the vaccine when compared to older children or adult. Moreover, during the study, researchers found a warning signal that might suggested that giving the vaccine to young children may not good. So this is why the FDA set the lower age limited for dengue vaccine to 9 years old. 

6. Research also showed that children who have been exposed to dengue virus actually responded better than those who never exposed to dengue virus before. It is likely that children at age less than 9 years may never been bitten by an infected mosquito (i.e. never exposed to virus). This group of children will get less benefit of the vaccine. So it is not recommended to use in this group.

7.  According to the #5, #6, we could adapt the research result to apply in traveler group. Let’s say, if Mr. A, a European traveler plan to visit Thailand for the first time. So he has never exposed to dengue virus in his life before. So it is not recommend to give him the vaccine since the benefit is less and there may be a safety concern as well. 

8. Currently, World Health Organization (WHO) recommends dengue vaccine in people age 9-45 years old who live in the dengue endemic area. There is no recommendation for travelers. For those who live in Thailand (Expat), we will consider to give the vaccine only to those who stay here at least 9 years. Since this group of expat might already been exposed to dengue virus (equivalent to local children age 9). If they just live here in Thailand for 1 year, we will not give (equivalent to children age 1).

9. In conclusion, let’s me repeat our recommendation again

We DO NOT recommend the use of dengue vaccine in travelers visiting Thailand. For those who live/work in Thailand (the expat), we also do not recommend. However if you are an expat lived in Thailand or other dengue risk area for at least 9 years, you may be eligible to get the vaccine.        

 

FAQ about dengue vaccine

1. What is the cost of dengue vaccine?

  • In our hospital, it is approx. 3,000 baht per dose.
  • You need to get three doses of vaccine on Day 0, 6th month and 12th month.

2. What is the indication of dengue vaccine?

  • Person aged between 9-45 years who lived in dengue risk area
  • No contraindication of vaccine i.e. no allergy, not pregnant, not breast-feeding, not immunocompromised, has no cancer, etc
  • There is no recommendation to use in travelers 

3. What is the efficacy of dengue vaccine?

  • Efficacy to prevent dengue infection around 65%
  • Research also showed that among people who get vaccine and develop dengue infection had less chance to be a severe form and has less chance to be hospitalized. 

4. I want to get dengue vaccine, what should I do?

  • Since dengue vaccine is a new vaccine, It is recommended to read/explore reliable article regarding dengue vaccine.
  • In our hospital, all travelers must consult with our doctor in order to get the vaccine prescription
  • It is recommended to make an appointment before visiting us.

5. Should I get dengue vaccine?

  • If you live in Thailand or other dengue risk area less than 9 years, it is not recommended to get the vaccine.
  • If you stay here in Thailand more than 9 years AND will stay in dengue risk area permanently, you may consider the vaccine. It is recommended to discuss with the doctor to learn more about benefit-cost-risk to get the vaccine.
  • For example, we know that the efficacy of vaccine is 65%, Mr A may think that it is not good since the efficacy is not 90+%.  While Mr. B may think that 65% protection rate is good enough and dengue infection is potentially fatal, and he hates dengue, so he wants to get vaccine. Both perspectives are fine. 
  • No matter you should to get dengue vaccine or not, it is recommended to prevent yourself against mosquito bite. Whenever you have high fever or suspected dengue infection, you need to see a doctor. 

6. How long will dengue vaccine protect me?

  • There are not enough scientific information to answer this question. However we know that in the clinical study, researchers followed the volunteers up to 6 years and there is no booster recommendation. Some still have antibodies.
  • But at 10, 15 years post vaccination, will volunteer still be protected against dengue or not? Unfortunately, at this point, no one knows the real answer, we need to wait for more information/research.

7. Where can I find more information about dengue vaccine?

  • World Health Organization. Dengue vaccine: WHO position paper – July 2016.
  • World Health Organization. Questions and Answers on Dengue vaccine.
  • Hadinegoro SR, et al. Efficacy and Long-Term Safety of a Dengue Vaccine in Regions of Endemic Disease. N Engl J Med. 2015;373(13):1195-206.
  • Capeding MR, et al. Clinical efficacy and safety of a novel tetravalent dengue vaccine in healthy children in Asia: a phase 3, randomised, observer-masked, placebo-controlled trial. Lancet. 2014;384(9951):1358-65.
  • Villar L, et al. Efficacy of a tetravalent dengue vaccine in children in Latin America. N Engl J Med. 2015;372(2):113-23.

“I have been diagnosed with Dengue fever. What should I do? Should I worry?”

Having a confirmation of dengue infection, the doctor might allow you to return back home after a thorough evaluation of the routine blood test (CBC). You will be reassured and encouraged to stay well hydrated by adequately drinking plenty of fluids, advised to return back if feeling worse or on the next follow up which usually is within a day or two later. The follow up visit is to assess the general condition and to assess the dynamic changes of the different cell counts in the blood test usually seen in dengue infection.

Several symptoms such as nausea with persistent vomiting, severe abdominal pain or any bleeding might require hospitalization. The laboratory marker i.e. decreasing trend of blood cells are also the signs that doctor consider and suggest hospitalization.

If you need to admit in the hospital, don’t panic. Since the course of hospitalization is usually uneventful in most cases and usually last not more than 3-4 days. During your stay in the hospital, the nurse and doctor will take care you. Generally, you are recommended to rest, drink or eat as much as you want and to be cautious for any possible bleeding such as epistaxis, bleeding per gum, or in woman, bleeding per vagina. The doctor may give you some intravenous fluid to ensure that you get adequate hydration. Close monitoring such as repeated measure of your pulse, blood pressure or blood checked might be required in some case. Normally, you will have fever for 4-5 days then will enter to the period of recovery.

Signs of recovery generally begin with regaining of appetite, able to drink plenty of fluids and void as much. You will have no fever and feel much better. The recovery phase is frequently associated with a generalized rash over the body, and itchiness over parts of the body. It is not harmful and the rash will be gone within 1-2 days.

Normally, the doctor will discharge you from the hospital once you have no fever for 24 hours and lab test is much improving. All laboratory parameters will usually return to normal within a week or two. Doctor may recommend you for a follow up visit to be sure that everything is returned to normal.

What should I do if I have fever, am I having malaria or dengue?

Everyone enjoys traveling; falling ill while traveling is unpleasant and can be worrying not to know what is happening or what to do next, especially being away from home.

It is not uncommon to wake up with a fever, a bit of nausea after being bitten by a few mosquitoes a week or two ago. You recall having been informed about malaria, dengue and other tropical diseases transmitted by mosquito on your visit to the travel clinic. Now it seems that you have fever, what should you do?

First of all, don’t panic. Let’s discuss about malaria first. In Thailand malaria transmission is limited to certain area around the borders of the country. However, if you develop a fever after having been trekking in the forest, exploring waterfalls, it would be necessary to know if it the fever is caused by malaria. You should go to see a doctor without delay. Malaria is treatable with effective anti-malarial medications. Cure and complete recovery are expected after successful treatment.

Waterfall near Thai_Myanmar border where malaria exist

Dengue on the other hand, is an urban disease. You can get dengue even you stay in big city such as Bangkok or Chiangmai. Most travelers with dengue infection will develop a fever with some uneasiness or discomfort, which many might mistake as flu. This is because the majority of individuals infected with dengue virus might have very mild non-specific symptoms which is difficult to distinguish from other diseases. For those who develop mild to moderate symptoms could have persistent high fever, associated with a headache which hurts over the eyes and forehead or flushing of the face including the neck.

There is almost always a loss of appetite, tends to taste weird and when the anorexia worsen, vomiting ensue. Severity of aches over the body and joints may vary from person to person but rarely someone experiences debilitating or excruciating bone pain. The feared sign of dengue infection is the bleeding manifestation. Mostly it would occur well after the 3rd day of illness, bleeding from the gums is more common and infrequently nose bleeds. Very few percent of people with dengue infection will turn into a severe form i.e. dengue shock which require intensive medical treatment.

Early diagnosis and proper treatment of dengue is a key. Here at the our Travel clinic, our doctors are experts in Tropical Medicine who are vigilant in diagnosing based on the history, clinical findings on physical examination and use of diagnostic kits such as the dengue antigen detection test kit or the dengue NS1 antigen (NS1Ag) test kit. This test is done using small amount of blood and the result is available in less than an hour. The advantage for the test kit is that it can be used early in the course of illness. It is also accurate and could confirm dengue infection.

What should I do if I am bitten by a dog?

Bitten or scratched by a dog, cat or monkey is a common problem seen in our travel clinic. Most important concern in this scenario is a rabies risk. Since it is a serious and untreatable disease. Once someone develop symptoms of rabies, it will always fatal.  So we have to do everything we can to prevent rabies virus when they have been bitten/scratched by a mammal. Here are some useful information and advice

1. Once you exposure to any mammal (dog, cat, monkey, etc), the first step is to clean your wound immediately with antiseptic or just soap and water. This is an important step that could minimize the risk of getting rabies. Do not forget to do this.

2. You can get rabies only when you ‘expose’ to an infected mammal. The keyword ‘expose’ is important and should not be confused. The World Health Organization (WHO) has classified the possible rabies exposure in three categories as followed;

Category Type of contact Post-exposure treatment
I Touching or feeding animals, licks on intact skin No vaccine is needed if history is reliable
II Nibbling of uncovered skin, minor scratches or abrasions without bleeding Immediate rabies vaccination
III Single or multiple transdermal bites or scratches, licks on broken skin; contamination of mucous membrane with saliva from licks, contacts with bats. Immediate vaccination and administration of rabies immunoglobulin

3. You’ll see, in most cases, if you’re bitten you are likely to have a category III exposure which require rabies vaccine and immunoglobulin. Rabies immunoglobulin, in simple word, is just a rabies antibody that could neutralize the virus at the wound. So the concept is, if someone has transdermal bite (bite that break to the deep layer of the skin); it is possible that rabies virus could find its way to the nervous system. So we immediately need something to neutralize it. We cannot just give a rabies vaccine and wait for the protection since it could take more than a week before a series of vaccine will become effective. And unfortunately, the incubation period of rabies could be as short as 7 days. No one would take that risk.

4. If you has been scratched by an animal, the wound is not deep and there is no bleeding. We could categorize as category II exposure. In this case, you just need a series of rabies vaccine i.e. 5 shots on Day 0,3,7,14,28.

5. However it is not always easy to categorize the exposure in the real life. Someone might get bit; the wound is small but there is some minimal bleeding or bruise. Should we categorize into category II or III. Sometimes it is difficult to say. However, giving that rabies is 100% fatal, so in the grey zone case, most doctors prefer to give ‘over’ treatment to ‘under’ treatment. We also agree, we prefer to err on the side of caution.

6. There is a common scenario that traveler has category III exposure, but rabies immunoglobulin is not available on the first visit. On that case, you still need to get the vaccine and should find the place where you can get the immunoglobulin without delay.

7. If you have already completed rabies pre-exposure series i.e. 3 shots, it is not necessary to receive immunoglobulin. You just need two shots of rabies vaccine on day 0 and day 3 once you exposure to animal.

8. If you’re not sure, whether you should go to see a doctor or not; or whether the scratch is severe or not. DO NOT try to consider it by yourself. You need a qualified medical doctor to assess for you. Visiting a doctor is an urgent issue after possible exposure to rabies virus.

9. In the standard recommendation, we do not use the ‘behaviour’ or the ‘looking’ of the dog/cat to consider the necessary of the rabies post-exposure treatment. Since even healthy-looking dog/cat could transmits rabies. So we will consider all exposure to animal is a rabies risk. We could be sure that there is no rabies risk when that dog/cat survive more than 10 days after exposure. However, the rabies post-exposure treatment must begin immediately on the day of exposure.

10. Once you get bitten/scratched, you should seek for medical care as soon as possible. No one knows the safe time-frame that you can delay, i.e. we have always been asked whether it is ok to delay the treatment for 12 hours/24 hours/48 hours, etc. Unfortunately, no one know the answer. Generally speaking you should do it as soon as possible.

Place where you can get rabies vaccine

Most hospitals in Thailand can provide rabies vaccine. However rabies immunoglobulin is available only in big/referral hospital only. If you’re in Bangkok, you may get rabies vaccine and immunoglobulin in our hospital.

Thai Travel Clinic (www.thaitravelclinic.com)
Hospital for Tropical Diseases
Faculty of Tropical Medicine, Mahidol University
420/6 Rajvithi Rd, Rajthewi
Bangkok 10400, Thailand

Remark:

* Rabies post-exposure treatment is costly especially when rabies immunoglobulin (RIG) is required. In our clinic, the cost of rabies vaccine is around 400 baht per shot and the rabies immunoglobulin (ERIG) is approx 2500-5000 baht (depend on the body weight).

* Pre-exposure prophylaxis is recommended and should be considered in some travelers. Please refer to this article: Rabies vaccine in Southeast Asia. Is it necessary?

Why we don’t set any vaccine bundle-package or promotion in our clinic?

Some travelers might wonder that why we do not set a vaccine-bundle package or any promotion in our clinic. Although it may be a good marketing idea for any clinics, we simply don’t do it.  Why? Here are some reasons/explanation:

1. We believe that the reasonable pre-travel vaccines for all travelers are not the same even they travel to the same destination. Risk of acquiring infectious diseases are different between person to person. So we need a proper risk-assessment in order to give a sound recommendation.

For example, a businessman who plan to visit Bangkok for only a week come to see me and ask for a vaccine, we may recommend none. In contrast to a backpacker who plan to traveling in Thailand for 2 months, in this case, we may recommend rabies vaccine, JE vaccine, HepA/B and tetanus vaccine. So we could not just develop a ‘vaccine-list’ that would fit for all.

2. Let’s say, if we could create a table like this for travelers to India, what do you think?

Recommended vaccine for India  Cost
Vaccine A 300 Baht
Vaccine B 700 Baht
Vaccine C 1,200 Baht
Package (A+B+C) 2,000 Baht (Save 200)

This table is easy to understand and will make some travelers feel great. Since if they choose to get all three vaccines they even get some discounts. But we will not do it.

Why??  We train our doctors to do their best risk assessment for each individuals and give sound and straightforward recommendation. Such as we have Mr. X in our clinic and his itinerary do not cause any risk from disease C, so we will recommend only vaccine A+B, not include C. On the other hand, if we see Mr Y and he will go to some remote area where disease D is common, so we will recommend vaccine A+B+C and also vaccine D.  You’ll see if we have a package like that, it may impact the doctors and travelers’ decision.

3. Although package and promotion is commonly used in many clinics/hospitals as a marketing tool, we  do think that marketing should not play any role in medicine. Otherwise it may distort the ethics and professionalism. So in order to maintain our ‘integrity’ we do not use any marketing tools in our clinic. You will never see somethings like: Buy 2 vaccines and get 20% discount, or Get these three vaccines for only 2,000 baht (save 200 baht). We will never do that.