Dengue Fever Vaccinations

[jayboy]

I am confused about the value of dengue vaccinations for children living in Bangkok who have never experienced dengue and are otherwise healthy.I have read up on the background but apart from learning about the two vaccines on offer in Thailand the advice seems contradictory.

 

This ad from Bangkok Hospital seems typical

 

https://www.bangkokhospital.com/en/package/new-type-of-preventive-vaccine-for-dengue-fever

 

But it fails to mention any of the caveats mentioned by other respectable sources e.g

 

https://www.thaitravelclinic.com/blog/vaccineinfo/dengue-vaccine-for-foreigners-travelers-in-thailand-should-i-get-it-update-2023.html

 

Experience advice from parents would be very much appreciated.

[Swiss1960]

My 16y old daughter caught dengue and her blood count was do bad, even a bruising could have let to significant internal bleeding. She was in the hospital for 6 days... after that, we did vaccinate her as soon as possible 

[Photoguy21]

Another vaccine being tested on the public

[jayboy]

46 minutes ago, Swiss1960 said:

My 16y old daughter caught dengue and her blood count was do bad, even a bruising could have let to significant internal bleeding. She was in the hospital for 6 days... after that, we did vaccinate her as soon as possible 

 

Sorry to hear that and hope she has fully recovered.From my reading of the literature, your decision to vaccinate was absolutely correct because she had already experienced the unpleasant dengue condition.

[NanLaew]

My understanding is that if you have never had dengue, the vaccine may make the symptoms suffered during your first infection more severe than they would be normally. Or they may not.

 

I also understand that if you have had dengue previously, the vaccine will most likely make the symptoms more severe than what was experienced the first time. This is due to dengue having at least three known variants, and the vaccine's interaction with your own antibodies may not be beneficial if the dengue re-infection is by a different variant.

 

I had dengue once and based on the above, I don't recommend it for my family members or myself.

[Polar Bear]

There are 4 strains of Dengue. You cannot catch a specific strain more than once, but you can catch all 4 strains independently. As a rough guide, the risk of infection in adults averages about 1% per month (though the risk is higher in some months than others.) If you live here for 10 years, you'll probably have it at least once. 

For most (but not all) people, it's relatively mild the first time they get it, and it's rare for someone to get seriously ill from their first infection. It's more common for people to not even realise they have it the first time, but the risks increase with each subsequent infection. Overall, 10-24 year olds have the highest infection rate. All Dengue infections are potentially far more dangerous in kids, especially under-5's. In kids, the first infection is more likely to be serious, and that risk increases exponentially with each infection, but fatalities are still rare.

There are two vaccines. The older one, Dengvaxia, isn't great. It's not that effective at preventing infection, and it is only suitable for people who have already had one strain of Dengue. If it's given to someone who has never had Dengue, they are more likely to have a bad reaction to the vaccine, and their first real Dengue infection might be worse than it would have been otherwise. I won't go into all the details, you can easily find the information online if you want it, but it should not be given to someone who has never had Dengue. Once you have had an initial Dengue infection, it does NOT make subsequent (2nd, 3rd, 4th) infections worse. 

It still prevents hospitalisation and severe illness in about 80% of people. Despite the problems with it, it was still recommended for kids who had previously had a Dengue infection because the risk to them is so great.

The second vaccine is the newer one, Qdenga. It is more effective at preventing infections (about 80% initially), and if you are one of the unlucky 20% who still get infected, it's around 90% effective at preventing hospitalisation. Even as its ability to prevent infection starts to wane, its ability to prevent hospitalisation holds up for at least 5 years. So again, although everyone would like to see a vaccine that is more effective at preventing infection, it's still a huge difference in reducing the overall risk. Also, it is more effective at preventing DENV2 infections than the other strains. (It is based on the DENV2 strain.) DENV2 is considered to be the most dangerous strain if it is contracted in subsequent infections. 

You can receive Qdenga whether you have previously had Dengue or not, as it does not interact with prior infections. It's licenced for people aged 4-60 in Thailand. 

I'm not a parent, but if I had a child, I would get them vaccinated with Qdenga. Having said that, I've had Qdenga myself, and it is probably the most physically painful vaccine I've ever had. It hurt a lot when it was given and for a couple of days afterwards. For that reason, I probably wouldn't give it to a 4 year old because it would be hard for them to understand what's happening. I'd wait until they were maybe 7 or 8, and you could talk to them about it first. But I would definitely want them to be vaccinated before they were 9 or 10 and in the high infection rate age group.
 

[K2938]

58 minutes ago, Polar Bear said:

You can receive Qdenga whether you have previously had Dengue or not, as it does not interact with prior infections. It's licenced for people aged 4-60 in Thailand. 

There is actually not enough data to decide at this point of time if it is really advisable to get Qdenga if you have not had dengue previously.  For this reason, respected Western health authorities such the German ones do not generally recommend Qdenga for people who have not had dengue yet at this point of time.  Also, the application of Qdenga for the U.S. was withdrawn for lack of sufficient data (which applicants generally do to prevent a rejection).  So this all seems to support a cautious approach which also falls in line with Mahidol University as quoted by the OP ( https://www.thaitravelclinic.com/blog/vaccineinfo/dengue-vaccine-for-foreigners-travelers-in-thailand-should-i-get-it-update-2023.html ).  Mahidol was actually also involved in the original development of Qdenga so what they say should have a lot of weight.  This is not just some random "travel clinic".

P.S.:  I was actually planning to get Qdenga, but in view of all this I decided to better wait.

Edited January 14 by K2938

[jayboy]

37 minutes ago, Polar Bear said:

The second vaccine is the newer one, Qdenga. It is more effective at preventing infections (about 80% initially)

 

Thank you, very useful.We can dismiss the older vaccine for all practical purposes.

 

I'm not sure whether dengue is endemic in Bangkok and whether the public health authorities have a vaccination programme for children in school.Also -and it's probably a silly question - how is it possible to know that Qdenga is effective at preventing 80% infections?

 

I think you may be right in your conclusion , but it's by no means an cut and dry matter.I'd be v.interested to know what Sheryl thinks.

[K2938]

9 minutes ago, jayboy said:

Also -and it's probably a silly question - how is it possible to know that Qdenga is effective at preventing 80% infections?

The manufacturer did a study, but again if you look at the data closely things do not look as great as they might appear:  https://www.nature.com/articles/d41586-022-03546-2

 

 

[Polar Bear]

3 hours ago, K2938 said:

There is actually not enough data to decide at this point of time if it is really advisable to get Qdenga if you have not had dengue previously.  For this reason, respected Western health authorities such the German ones do not generally recommend Qdenga for people who have not had dengue yet at this point of time.  

The EU and UK, among others that have already approved it, would disagree. It is licenced throughout the EU for people who are seropositive or seronegative. The European Medicine Agency publish all of its documentation on the process if you are interested in it. 

I would not expect Germany or any other non-endemic country to recommend it. The risk profile for travel vaccines in Germany is wildly different to that of a child living in Bangkok. If someone from Germany started visiting Thailand and stayed for 1 month every year, they would probably contract their first Dengue infection within the first one hundred years. If a child lives in Bangkok between the ages of 10-24, they will be in the minority if they haven't had at least one infection, and many will already be on subsequent infections by the time they reach 25. 

Since the vaccine primarily protects against hospitalisations from subsequent infections, it would make no sense to recommend it to someone who is highly unlikely to catch it once, let alone twice. 

Of course, the catch with the advice in Germany is that if a tourist does contract it, many of them won't know they even had it, so they won't know it then becomes recommended if they are at risk of a subsequent infection. Unless they are routinely offering blood tests first, which seems unlikely. 

Brazil has just made it a core vaccine, starting this year, I believe. So that will massively increase the data available over the next few years. 
 

 

3 hours ago, K2938 said:

oint of time.  Also, the application of Qdenga for the U.S. was withdrawn for lack of sufficient data (which applicants generally do to prevent a rejection).  So this all seems to support a cautious approach which also falls in line with Mahidol University as quoted by the OP ( https://www.thaitravelclinic.com/blog/vaccineinfo/dengue-vaccine-for-foreigners-travelers-in-thailand-should-i-get-it-update-2023.html ).  Mahidol was actually also involved in the original development of Qdenga so what they say should have a lot of weight.  This is not just some random "travel clinic".

 

Yes, Takeda withdrew their application in the USA. The FDA made multiple requests for additional data, which is normal, and accepted everything Takeda provided. Until the last request, when they wanted data that wasn't available because it had never been collected. It would have meant starting an entirely new set of trials, and Takeda decided that wasn't viable at the time, so they withdrew their application. 

It was a surprising turn of events because the CDC had been involved in the vaccine development and in designing the trials. The USA agencies approved the trials and data collection before it started, and they undertook inspections during the trials, which they all passed. Then, once the data collection was complete, they suddenly decided they wanted something else they hadn't asked for previously, and you can't collect data retrospectively. 

It'll be interesting to see whether Takeda bothers to run new trials for the USA eventually or just skips that market.

 

3 hours ago, K2938 said:

P.S.:  I was actually planning to get Qdenga, but in view of all this I decided to better wait.

It isn't generally recommended for tourists or expats, or anyone intending to spend less than 10 years in a Dengue-endemic country. If you weren't raised in a Dengue-endemic country and have no reason to think you've had it before, the risk is very small, especially as infection levels tend to reduce with age. If you know, or strongly suspect, that you have had it before, the risk profile is very different.

 

If you are already 60+ when you start spending a significant amount of time in Thailand, you are already too old for the vaccine anyway, as it's only licenced up to 60 here. 

But none of this is relevant to Jayboy's question about a child living in Bangkok.

 

[connda]

I've had Dengue and I've researched the vaccines.  And I try to keep current with Dengue vaccine development.

From the CDC.  Read and heed:
https://www.cdc.gov/vaccines/vpd/dengue/public/index.html

Bottom line:  If you haven't have Dengue before the vaccine, you may be setting yourself up for Antibody Dependent Enhancement (ADE) that can be fatal.  That is the problem with Dengue as well as Dengue vaccination research and development. 
https://pubmed.ncbi.nlm.nih.gov/33194810/

[Polar Bear]

4 hours ago, jayboy said:

I'm not sure whether dengue is endemic in Bangkok and whether the public health authorities have a vaccination programme for children in school.

Dengue is endemic in Thailand and one of the top 5 countries for it globally. There are currently 10 provinces classed as high-risk by the Thai gov, and Bangkok is one of them. They are listed here 
https://reliefweb.int/report/thailand/dengue-fever-cases-could-reach-3-year-peak-health-ministry

It's cyclical with an epidemic roughly every three or four years. 2023 was an epidemic year. 

As far as I know, Dengvaxia was never a routine vaccination for kids in Thailand. It would have been complicated to administer, as they would need the blood test to show prior infection first. 

Qdenga is on the Ministry of Public Health's vaccine priority list for kids, at the second rank level, so a future prospect but not currently happening. But I don't have a source for that, as I saw it in a presentation.

 

4 hours ago, jayboy said:

Also -and it's probably a silly question - how is it possible to know that Qdenga is effective at preventing 80% infections?

You compare the number of infections in the vaccinated group with the number of infections in the placebo group over the same period of time.

(I shouldn't have joked about the 'unlucky 20%' earlier. It misrepresents what vaccine efficacy means.)

[connda]

5 hours ago, Polar Bear said:

I won't go into all the details, you can easily find the information online if you want it

https://pubmed.ncbi.nlm.nih.gov/33194810/

 

[Polar Bear]

3 minutes ago, connda said:

I've had Dengue and I've researched the vaccines.  And I try to keep current with Dengue vaccine development.

From the CDC.  Read and heed:
https://www.cdc.gov/vaccines/vpd/dengue/public/index.html

Bottom line:  If you haven't have Dengue before the vaccine, you may be setting yourself up for Antibody Dependent Enhancement (ADE) that can be fatal.  That is the problem with Dengue as well as Dengue vaccination research and development. 
https://pubmed.ncbi.nlm.nih.gov/33194810/

This is well documented with the older vaccine Dengvaxia, which both of these sources refer to. 

It has not been seen (yet?) with Qdenga, and there have been numerous studies on it since the problems with Dengvaxia.

https://www.ema.europa.eu/en/documents/rmp-summary/qdenga-epar-risk-management-plan_en.pdf
 

The totality of data on virologically confirmed dengue (VCD), hospitalized VCD, and severe forms of dengue, along with the clinical characteristics of these cases, as assessed in Trials DEN-301, DEN313, and DEN-204, did not reveal an identified risk of increased disease severity or disease enhancement attributable to vaccination in the post-vaccination follow-up period. 

https://www.sciencedirect.com/science/article/pii/S1477893923000583

No indication of disease enhancement has been seen in the TIDES study up until 4,5 years after the second vaccine dose. 

 

 

[K2938]

2 minutes ago, Polar Bear said:

It has not been seen (yet?) with Qdenga, and there have been numerous studies on it since the problems with Dengvaxia.

https://www.ema.europa.eu/en/documents/rmp-summary/qdenga-epar-risk-management-plan_en.pdf
 

The totality of data on virologically confirmed dengue (VCD), hospitalized VCD, and severe forms of dengue, along with the clinical characteristics of these cases, as assessed in Trials DEN-301, DEN313, and DEN-204, did not reveal an identified risk of increased disease severity or disease enhancement attributable to vaccination in the post-vaccination follow-up period. 

https://www.sciencedirect.com/science/article/pii/S1477893923000583

No indication of disease enhancement has been seen in the TIDES study up until 4,5 years after the second vaccine dose. 

The links cited by connda indeed concern Dengvaxia, but a sufficient number of eminent scientists having reviewed the Qdenga data has concluded that there is really insufficient data to decide if Qdenga does not cause the same problem for dengue-naïve people that one should be careful IF one has never had dengue yet.  This is for example discussed in the Nature article I quoted above, this is also the concern of the Germans, this is the concern of Mahidol and I have also seen an article of some renowned Swedish scientists (from Karolinska if I remember correctly) pointing out the same.  Now of course there are also other opinions, but I personally prefer to be on the careful side as a dengue-naïve person.  Moreover, the first time you get dengue the likelihood of it killing you is very very small, so the risk is quite small, and the vaccine is more effective if you already had dengue as well.   

[Polar Bear]

9 minutes ago, K2938 said:

The links cited by connda indeed concern Dengvaxia, but a sufficient number of eminent scientists having reviewed the Qdenga data has concluded that there is really insufficient data to decide if Qdenga does not cause the same problem for dengue-naïve people that one should be careful IF one has never had dengue yet.  This is for example discussed in the Nature article I quoted above, this is also the concern of the Germans, this is the concern of Mahidol and I have also seen an article of some renowned Swedish scientists (from Karolinska if I remember correctly) pointing out the same.  Now of course there are also other opinions, but I personally prefer to be on the careful side as a dengue-naïve person.  Moreover, the first time you get dengue the likelihood of it killing you is very very small, so the risk is quite small, and the vaccine is more effective if you already had dengue as well.   

 

A 'sufficient number of eminent scientists'? How many is 'sufficient'? I prefer to just go by the data, and as The Nature article you cite says, 'no cases of ADE have been reported in clinical trials of Qdenga'.

One of the sources I linked earlier was the documentation of approval by the Swedish Society for Infectious Diseases Physicians. If there were other Swedish scientists who disagreed, I guess there wasn't a sufficient number of them to sway the decision. 

But regardless, with Brazil and potentially Indonesia starting mass vaccination programs, we'll have a lot more data soon.

In the meantime, everyone is free to make their own decision on it. If you prefer to take a more cautious approach, that's entirely your choice. I certainly have no argument with you about it. 

[connda]

1 hour ago, Polar Bear said:

 

A 'sufficient number of eminent scientists'? How many is 'sufficient'? I prefer to just go by the data, and as The Nature article you cite says, 'no cases of ADE have been reported in clinical trials of Qdenga'.

One of the sources I linked earlier was the documentation of approval by the Swedish Society for Infectious Diseases Physicians. If there were other Swedish scientists who disagreed, I guess there wasn't a sufficient number of them to sway the decision. 

But regardless, with Brazil and potentially Indonesia starting mass vaccination programs, we'll have a lot more data soon.

In the meantime, everyone is free to make their own decision on it. If you prefer to take a more cautious approach, that's entirely your choice. I certainly have no argument with you about it. 

Just read the medical literature and keep in reviewing it over time.  Over time a solid vaccine that has been fully tested (long-term included).  In the future I'm sure this will be addressed and a effective vaccine create.  But it's going to take time.

Right now?  You options are limited and you really need to understand the issue with the vaccines (and ADE) and make a choice based on informed consent. 
I can't imagine the horror of giving a Dengue vaccine to a child who had never had Dengue, and end up ending that child's life.

Be informed.  Don't take it lightly.

[PPMMUU]

The case of Dengvaxia is another great example that the scientific method and scientific community do work as they are supposed to. Once a vaccine shows any real hint of not being really good, scientists know, and we know. Nothing is hidden.