First published in ITIJ 116, September 2010
Travel vaccine programmes are recommended by most state health services around the world, but why are these so important and do travel insurers have to pick up the tab if travellers fail to heed travel medical advice? Robert Steffen gets to the point
Travel trends have changed in recent times, as travel insurers are well aware; with vacationers favouring adventure holidays over traditional beach destinations at an increasing rate. Such adventure holidays, or trips off the beaten track, pose a greater risk to travellers’ health, which is why vaccines appropriate to the country or countries being visited are more important than ever. Unfortunately, however, many travellers – especially business travellers – ignore the vaccination recommendations put forward by both state health services and private travel clinics.
But once a recommendation is issued by a health authority, do travellers have to pay the price (in more ways than one) of ignoring such advice, or is it travel insurers who have to pick up the pieces when travellers become sick when abroad? What checks do International Private Medical Insurance (IPMI) providers make before issuing a policy to someone relocating to an area with a known preventable-disease risk? And why is it so important for travellers to receive the correct inoculations?
This won't hurt a bit
Travel vaccines contribute heavily to keeping travellers healthy during and after a journey abroad. Obviously, not every available vaccine is recommended for every traveller; recommended vaccines are based on environmental factors relative to the destination, as well as such issues as duration of stay. But the reason for travel and travel style must also be considered. For example, those visiting friends and relatives have been shown to be at greater risk of infection. Thus, evidence-based decisions must determine the recommendation of a vaccination.
Some countries require visitors to be protected against certain diseases before they are allowed to enter. For example, many countries require visitors to have had a yellow fever vaccination, particularly if they have travelled to the country from another that has infected areas. Such countries will require proof of inoculation in the form of an International Certificate of Vaccination, which is a document approved by the World Health Organization (WHO) to verify that proper procedures were followed in administrating vaccinations for foreign travel. These documents are designed to fit into a passport and are issued by doctors’ surgeries and health clinics.
Yellow fever is a virus that is passed to humans by bites from infected mosquitoes. It is endemic in tropical Africa and South America, where a few cases, often fatal, have been reported in unvaccinated travellers. In view of concerns about rare but serious side effects from the yellow fever vaccine, it should only be used when clearly indicated, and should not be given, for example, to those who have had a severe reaction in the past to eggs. Based on the WHO’s International Health Regulations, only travel clinics or medical centres with special authorisation are licensed to give this vaccine.
Some countries require visitors to be protected against certain diseases before they are allowed to enter
Additionally, the Kingdom of Saudi Arabia requires proof of vaccination against meningococcal disease for all pilgrims to Mecca (Hajj, Umrah).
A doctor or nurse consultation prior to travel is a good opportunity to ascertain that routine immunisations have been performed, especially as it is often necessary to update immunity against diphtheria and tetanus, and some younger travellers may have missed immunisations against measles. In fact, a lack of immunity due to non-compliance with recommendations that children and younger adults ought to have received two doses of the measles vaccine resulted in a measles epidemic in Switzerland, which saw more than 4,000 cases of the contagious viral illness. Ten per cent of those affected needed to be hospitalised, eight infections resulted in encephalitis, and at least one patient has permanent sequelae (disorders that are a result of the original illness). Viral analysis has further determined that the epidemic was imported from Southeast Asia, and some anthroposophic school classes exported it to other German-speaking countries. This outbreak meant Switzerland accounted for 42 per cent of all cases of measles in Europe in the third quarter of 2007, and led to a warning being issued to all travellers planning to attend the country’s hosting of football’s EURO 2008. Furthermore, in Canada, a Japanese group of tourists was recently quarantined before their return flight home because of a measles outbreak.
Travel health consultations would also flag up those younger travellers who need catch-up doses of vaccines such as hepatitis A and/or B, or human papilloma virus. Furthermore, according to most national immunisation programmes, senior travellers – who make up 15 per cent of the travelling population – ought to be protected against influenza during the winter season at their respective destination. In fact, influenza is the most commonly occurring vaccine-preventable disease; with an incidence rate of one per cent per month. In the tropics, infection occurs all year.
The second most frequently observed disease amongst non-immune travellers to developing countries is hepatitis A, which is most commonly transmitted via contaminated food or drinking water, and has an average incidence rate of 30 per 100,000 per month. Luxury hotels are more likely to pass on the virus, as staff handle food more frequently, thus increasing the risk of infection. Hepatitis A is usually asymptomatic in children, who may thus inadvertently cause outbreaks, particularly if they attend a kindergarten or similar institution; so routinely vaccinating children would be a sensible option. Furthermore, the disease of the liver is fatal for one in 50 of all those over the age of 40 who contracts the disease.
Many immunisations are recommended for special-risk groups only, though there is a growing tendency in many countries to immunise at least all young travellers to developing countries against hepatitis B. Around 14 per cent of all travellers expose themselves – either voluntarily or involuntarily – to the virus, which is predominantly sexually contracted (five per cent of holidaymakers will have casual sex on holiday), but can also be picked up through poorly cleaned medical equipment (such as syringes), or exposure to very poor hygeine. For expatriates, hepatitis B is mainly a problem for those living close to the local population. The monthly incidence rate of hepatitis B is 25 per 100,000 for symptomatic infections and between 80 and 420 per 100,000 for all infections.
there is a growing tendency in many countries to immunise at least all young travellers to developing countries against hepatitis B
Other vaccine-preventable diseases include typhoid fever, which is diagnosed with an incidence rate of 30 per 100,000 per month among travellers to the Indian subcontinent; North (except Tunisia), Central and West Africa; and Peru. Elsewhere, this rate is tenfold lower. The rate of cholera is only approximately 0.3 per 100,000, although infections without symptoms or a clinical picture indistinguishable from travellers’ diarrhoea may be more frequent.
Furthermore, travellers are at a low risk of several vaccine-preventable neurological infections that can be devastating. Every year, many of the two to four per cent of travellers who experience an animal bite are at risk of rabies. Rabies is particularly a risk for those who are in close contact with locals over a prolonged time, such as missionaries and, potentially, expatriates; those travelling overland by bike; those working with animals; and those who explore caves. Children often have a shorter incubation period, and they often fail to report the bite; but they are comparatively frequent victims of rabies. Rabies still has a 100 per cent case fatality rate, unless post-exposure prophylaxis has been initiated before symptoms develop.
Meningococcal meningitis, another vaccine-preventable neurological disease, is rare even in travellers staying in countries where the infection is highly endemic, such as in the sub-Saharan African Meningitis Belt, where almost annual epidemics are reported mainly between December and June. A few dozen cases of Japanese encephalitis have been diagnosed in travellers within the last 25 years, yet the incidence rate for both this and meningococcal meningitis infections among civilians is only around one per million. Those affected, however, have a substantial risk of death or of survival with sequelae. There is a new vaccine available for Japanese encephalitis, but if all 17 million visitors to Asian endemic areas were to be immunised against the disease, it would cost around €2.9 billion. This, naturally, raises the question of who should be immunised.
Although between 2000 and 2004, just 1.4 per cent of French people abroad had died of infection-related causes (compared to 28.1 per cent who had perished in traffic accidents), vaccinations for those people who will potentially put themselves at risk when travelling are an essential pain in the arm. Correct priorities are, however, paramount when deciding which vaccines are essential for future travellers: According to most expert groups, many travel immunisations are reserved for ‘at-risk groups’. Above all, one should not vaccinate against rare risks while leaving the traveller unprotected against far more frequent diseases of similar severity.
if all 17 million visitors to Asian endemic areas were to be immunised against [Japanese encephalitis], it would cost around €2.9 billion
To conduct the necessary risk assessment, travel health professionals ought to know the planned travel itinerary of their client, such as destination, duration of stay, exposure to the local population, and proposed standard of food and beverage intake. Additionally, they should take into account future travel plans to determine a cumulative exposure at an early stage. The travel insurance industry should sit down with underwriters and medical professionals to draw new conclusions as to who should be immunised against infections such as rabies, and formulate a way to encourage people to take appropriate health measures, such as vaccinations, before being accepted for insurance.