Dengue Fever and Vaccination: Navigating Recommendations and Risks
More Programs and Publications Featuring Dr. Rodney Rohde
In this program:
Dengue fever has an available vaccine, but what should travelers and others know about dengue vaccination? Medical laboratory scientist Dr. Rodney Rohde discusses key factors in navigating dengue risks versus vaccine recommendations, concerns for children and immunocompromised individuals, dengue types, and proactive measures to protect against dengue.
Transcript
Interviewer:
According to the CDC, the vaccine for dengue is recommended for use in children 9 through 16 with laboratory confirmation of a previous dengue infection while living in areas where dengue is common. However, the vaccine is not approved for use in U.S. travelers who are visiting, but not living in an area where dengue is common. So why are there distinctions for who should and who shouldn't receive the vaccine?
Dr. Rodney Rohde:
So the reason behind that restriction around vaccines is really around safety concerns. So, the FDA actually does not approve the vaccine for children under 6, regardless of whether they've had a previous dengue infection or not. That's because children roughly under 9, when you think about the global prevalence of dengue, children under 9 are less likely to have had an infection and are at higher risk of severe dengue and hospitalization if they get it after being vaccinated, right? So what this is, is the vaccine is only for people who have already had dengue, and you actually want to have that confirmed by a blood test. So we don't experience this a lot in the United States, because we don't have this particular mosquito-borne virus. So we're watching it. It is exploding right now.
Deandre, in places like the America, South America, Latin America, Brazil, Argentina, people who haven't had dengue are actually at a higher risk of severe dengue if they get it after being vaccinated. Antibody-dependent enhancement, also known as ADE, is this kind of bizarre phenomenon that can occur in this situation. So what happens is that a second dengue infection can be more severe than the first due to this process called ADE. And ADE occurs when antibodies from a previous infection and in this case dengue infection, bind to a different serotype of the virus, that are unable to neutralize it.
And when that happens, it actually allows that different serotype to enter the immune cells and replicate kind of out of control. And that can increase spiral infection, almost causing a super infection. So you don't want to vaccinate everybody early, because they're going to build a response and then if they get an actual dengue infection, that particular serotype, if it's different than the one in the vaccine, can be really problematic. It can also happen naturally. So if a person has dengue at age 10 and it's type 1, but they get a second infection, say two years later, and it's type 3, then their body is, their immune system's not going to work the way you think it would work. So it's not a pan vaccine. In other words, it doesn't cover all four serotypes, and you can have this ADE response.
And so it's just kind of weird, because that second infection can trigger an immune response to the first serotype, and it's ineffective against the new one. And that allows the virus to have kind of this super amplification and that can lead to things like by the way, these sound scary, dengue hemorrhagic fever, and those can be life-threatening. Right now that's kind of what the World Health Organization and CDC is recommending. Hopefully they'll come up with a vaccine that can protect against all four serotypes, and you don't have that type of ADE response. Kind of a bizarre situation with that.
Interviewer:
It is. So are there concerns for having infection when you're beyond the age of 16 for adults? What is the risk for adults?
Dr. Rodney Rohde:
Yeah, so it's not quite as bad, but they still are recommending that you don't get it, unless you've actually had dengue. So, as strange as it sounds, that's kind of the opposite of what we typically think about for vaccination. But because it has this ADE kind of effect, that's kind of the recommendation.
Interviewer:
Okay. So if such restrictions are in place, are there people who otherwise should receive the vaccination that should consider not getting it, say because of comorbidities?
Dr. Rodney Rohde:
Yeah. So to my understanding the WHO and CDC do not recommend it for pregnant women. Women of childbearing potential should actually avoid pregnancy for about a month if they do get vaccinated later in life. So there are some real specific details around certain populations. People with immune deficiencies, CDC and WHO do not recommend the vaccine for people that have severe immunodeficiencies or immunosuppression. So things like HIV+ are individuals that might be on immunosuppressive drugs for, you know, they got a new kidney and they, and they're on a particular drug to kind of help the body accept that kidney. They're actually told not to receive this vaccine. So, again, with this particular question and this particular situation, individuals out there that are traveling you absolutely want to visit with your physician
It really should be a conversation you have with your physician or other experts that work in travel medicine. There's actually travel medicine experts, with CDC and then some health departments that you can kind of consult with. So people don't always think about these, Deandre, but we really should encourage the ongoing education and awareness around travel, medical information so that if you are traveling, this could even be within the United States to kind of understand if you're going into a certain region, are there more risk, are there more risk?
Interviewer:
So this topic, I'm sure is concerning to people that are traveling to areas where dengue fever is prevalent, but are there alternatives to the vaccine to protect travelers just to kind of maybe put their mind at ease?
Dr. Rodney Rohde:
Yeah. Such a great question. Such a good awareness piece to talk about. So whether you're traveling, definitely when you're traveling, out of the country and you're going abroad, you can continue to protect yourself and your family and loved ones specifically from dengue but also probably from malaria and yellow fever, West Nile, or other types of mosquito-borne viruses by preventing mosquito bites. And it sounds really simple but you want to kind of do that by wearing, you know, long sleeves, pants. This may not be fun if you're in a tropical area, but it's important. And using products that have DEET, D-E-E-T, which is a mosquito repellent, controlling mosquitoes. So if you're going to be somewhere for a while make sure you have a mosquito netting to sleep under. If you're in an open air tent, you can actually pack it yourself believe it or not.
Or if you're inside, make sure there's screens and things that help keep out mosquitoes and other biting insects. You can even buy certain products, even abroad that allow you to spray the perimeter of your yard or your abode where you're staying. And it can kind of control the types of mosquitoes that are in that area. And so if you're traveling specifically and you're worried about dengue, but right now it's in many countries globally, including the Americas, specifically South and Latin America, Africa, the Middle East Asia, and a lot of the Pacific Islands. So think tropics, that's typically what you're dealing with, that about half of the world's population, about 4 billion people live in areas that are always at risk of dengue, malaria, things like that.
So again, in America, we're very fortunate because at least for now, our geographic alignment on the equator and above and below the equator are a little less hospitable to certain things. But we are seeing an incursion of specific mosquito species-specific ticks, things called midges and gnats and biting flies and things like that. So, I don't know what's going to happen in the next 20 to 30 to 50 years in the U.S. but we may see a kind of an up prevalence in some of these types of diseases we often think are over there, right? We are seeing some of that happen in the U.S.
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