The vaccines you need to know about before you travel

(CNN) — Few things can ruin a vacation faster than illness.

But while a mild stomach bug will probably affect most travelers at some point, there are far more dangerous diseases – including potentially lethal ones – adventurers should know how to protect themselves against.

Global concern is mounting over the spread of mpox, a viral illness formerly known as monkeypox, that initially killed 1 in 10 people who contracted it, but now kills up to 3.3%.

In August, Sweden became the first country outside the African continent to confirm a case of the newer and more severe mpox strain, clade Ib, which has now also spread to Asia, with a confirmed case in Thailand and suspected cases in Pakistan and the Philippines.

International concern

The World Health Organization (WHO) has declared the ongoing mpox outbreak across more than a dozen central African nations a “public health emergency of international concern,” the highest level of alarm under international health law.

The US Centers for Disease Control and Prevention (CDC) recommends vaccination with two doses of the Jynneos mpox vaccine for people in the US at high risk of catching the virus.

In terms of bite prevention, travelers are urged to use insect repellent and wear permethrin-treated long-sleeved shirts and long pants when outdoors – the same advice as for other mosquito-borne diseases such as malaria or dengue fever.

Both have also been in the news lately, this time for more positive reasons.

Until recently, there wasn’t a widely available dengue vaccine for travelers. But in the past couple of years, a vaccine called Qdenga has been rolled out in the UK, the European Union and some countries outside Europe, while Dengvaxia is offered in the United States.

But according to Dr. Nicky Longley, consultant in infectious diseases and travel medicine at The Hospital for Tropical Diseases (HTD) at University College London Hospitals, dengue vaccination is not quite the silver bullet travelers had hoped for.

“The Qdenga vaccine reduces the risk of getting severely ill and dying if you catch dengue a second time, but if you haven’t had dengue before, it offers almost no protection,” she says, “and there is a theoretical risk that it might increase your risk of severe infection.”

Longley advises people who haven’t previously contracted the virus to hold off on the vaccine while trials are still ongoing, and instead take the above-mentioned precautions against mosquito bites – as should everyone, regardless of vaccination status.

One traveler who welcomes the arrival of the new Qdenga vaccine is UK-based travel writer Chris Dwyer.

After catching dengue while on vacation in Malaysia in 2014, he developed joint pain, weak limbs, a fever and a temperature that got progressively worse.

Dwyer had to be hospitalized and put on a drip while doctors monitored his liver and white blood cell count.

He eventually recovered, but the experience was clearly harrowing, and Dwyer knows that having previously been infected with dengue, he would be at even greater risk if he were to catch it a second time.

“I am seriously considering getting jabbed with Qdenga now, as I’m frequently in Asia and know how dangerous it would be to get sick again,” Dwyer says.

Meanwhile, headlines proclaiming that malaria could be eradicated within a decade are generating excitement after the development of an affordable vaccine against the devastating disease that kills 600,000 people, the vast majority being African children under the age of 5, every year.

Malaria is a disease spread when the female anopheline mosquito feeds on a person with malaria and then feeds on another.

Risk of infection

Babies in South Sudan and the Ivory Coast were given the first doses of the vaccine last month, with more African countries said to be authorizing it.

It’s good news for the world’s second-most populous continent, but the chances that it could also result in a malaria vaccine for global travelers within a similar time frame are “almost zero,” says Longley.

“It’s just not a suitable vaccine for travelers, because you need constant boosters and exposure, and it doesn’t offer full protection.”

What it does do, she explains, is reduce the risk of death in children, and once a whole population is vaccinated against malaria, the disease will eventually be eradicated.

But we are still a long way away from a malaria-free world, and anyone visiting affected regions (it can occur in the US, although cases are relatively rare) should be aware of how to do so safely and responsibly.

Equally keen to spread that message is Anniina Sandberg, the Finnish founder of boutique travel agency Visit Natives, who has been exploring remote regions of Africa for at least two decades.

As a professional traveler, she knows exactly which antimalarial drug works best for her and always packs mosquito nets when traveling to the African savanna, not just for her own safety but also because they make lifesaving gifts for local communities.

However, Sandberg herself once came close to death after getting ill on a trip many years ago and wants to share her experience as a cautionary tale.

Ahead of a year-long field trip among the Maasai in Tanzania when she was still a student, Sandberg was prescribed an antimalarial drug in combination with antibiotics. However, after a few months, the daily medication “began to seem unnecessary.”

“I noticed that the local population would regularly get malaria and recover from it, so I naively began to think of it as just a bout of flu,” she says.

“Of course, it’s a lot more dangerous than that, and as soon as I stopped taking the tablets, I got very sick, with a high fever, aches and pains.”

Even though she visited a hospital and was given malaria medication, Sandberg’s condition rapidly deteriorated with additional severe stomach flu.

After she was rushed back to the hospital, it transpired that she didn’t just have malaria but also typhoid fever, a bacterial infection common in parts of the world with poor sanitation and limited access to clean water.

Typhoid vaccines are widely available, with booster doses recommended every few years.

Sandberg’s ordeal didn’t put her off intrepid adventures.

“You can be super cautious, but you can never eliminate every health risk when traveling, in any destination,” says Sandberg, who also had a rabies scare a few years ago.

While visiting the Tanzanian Datoga tribe, whose traditional way of life revolves around herding sheep on the savanna, she spotted an animal in the herd that was clearly very unwell.

“I couldn’t know for sure if it had rabies or something else, but it was definitely very sick, and I did my best to avoid it,” she says.

Taking precautions

However, a few days later, Sandberg suddenly realized that the sheep was right behind her and had just licked her foot, where she had a broken blister.

“I got very anxious,” she says. “I knew I had to seek medical help as soon as possible.”

As she was miles from a hospital, Sandberg had to wait until her return to Helsinki, Finland, a few days later before she could be given a course of post-exposure rabies shots.

This is vital when there is a risk of infection, even if you have been vaccinated against rabies; initial vaccination just buys you more time.

“If you haven’t had the vaccine before, we normally say you should start treatment within a week, but obviously the sooner the better,” advises the HTD’s Longley.

The length of time it would take to develop rabies, she clarifies, depends on the location of the infected wound. It could take weeks or even months for the virus to enter the nervous system and reach the spinal cord and the brain. Once it does, there is no hope of survival.

With successful post-exposure treatment being a race against time, there have been cases of people choosing to seek treatment locally rather than flying home, only to find out later that it wasn’t actually the rabies vaccine they were given.

In a foreign environment, Longley warns, “you can’t necessarily know if the vaccine you’re getting is verified or not, or if it has been stored at the right temperature.”

Rabies vaccination is “super important,” she says, “because rabies is relatively widespread.”

Contrary to popular perception, the virus isn’t just a threat mainly in Asia. It’s present in more than 150 countries across every continent except Antarctica.

“There are bits of Europe, bits of the Americas – places you wouldn’t necessarily think of – where it is also a big risk,” says Longley.

Tick-borne encephalitis (TBE), a human viral infectious disease that affects the central nervous system and circulates in various parts of the world, some far from tropical, is another virus whose risk people often underestimate.

“There are parts of central Europe for which we would definitely recommend vaccinating against TBE, especially if you’re going hiking or camping,” says Longley.

“TBE is not rabies at all, but like with rabies, if you have TBE, there isn’t a specific treatment for it, and although the majority of people will recover, some people are severely unwell with it and can become disabled, and there are some deaths with it.

“If you are someone who is going to potentially be exposed to lots of ticks regularly, it’s well worth investing in the vaccine.”

The cost of vaccines – for TBE and generally – can vary significantly between clinics.

It’s worth shopping around for affordable vaccines, says Longley, but more important still is ensuring that the health advice you seek out ahead of a trip is the best possible.

“Actually, the advice is often more important than the vaccine you think you want,” adds Longley.

Which vaccines do you need?

Childhood vaccination is one of the most effective public health strategies to control and prevent disease.

In the United States, several vaccines are included in the standard recommendations for children at specific ages between birth and 10 years, including hepatitis A, measles, Covid, mumps and rubella. More, like tetanus and diphtheria, are added for adolescent. The CDC has a full list, but its also advisable to ask your doctor.

Adults are advised to keep a record of their immunizations and when they need to be boosted. When planning a trip, it is a good idea to consult the CDC’s destination pages for travel health information, to ensure that you have all the recommended and required vaccines for your destination, and know how else to protect yourself from the risk of disease.

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