Travel vaccinations

Global travel trends have meant a huge increase in the numbers of people travelling abroad and to increasingly remote countries. Over 900 million people travel abroad every year. For many of those travellers this will involve exposure to disease pathogens they do not normally encounter and a specific immunisation schedule will be advisable in order to cover them for diseases against which they will not have been vaccinated as routine in the UK.

Travel vaccinations are an essential part of holiday and travel planning. This is something that should not be left to the last minute, as not all vaccines are instantly effective, not all vaccines can be given together and some vaccination involves a course of two or more injections at specified intervals before the best possible levels of immunity are attained. It's also important to check that the UK schedule of vaccinations is up to date.

Healthcare professionals should work within their areas of competence.¹ If a patient asks their NHS GP about travel vaccinations with which the GP is not familiar, and which are not available on the NHS, the only action should be to direct them to a private travel clinic. Those professionals who do give advice on foreign travel need a working knowledge of the diseases concerned and an understanding of how they are acquired and how they may be best avoided.

Where to get up-to-date advice

The risks, recommendations and requirements regarding travel vaccinations change over time, both because of fluctuations in local conditions such as prevalence of insect vectors and local outbreaks of unusual disease and also because of changes in global disease patterns, new vaccine developments and emerging evidence. For this reason it is important to supplement knowledge with access to an up-to-date travel website and with reference to sites such as the National Travel Health Network and Centre (NaTHNaC) or the UK green book.²³

The Travel advice by country page offers country specific information on risks and vaccination requirements.

Mandatory vaccinations

There are very few mandatory immunisation requirements for travellers, although occasionally restrictions are put in place by specific countries because of disease outbreaks.

• Yellow fever vaccination is required for a number of countries where yellow fever is endemic or where there are mosquito vectors and primates with the potential to act as a reservoir for a new epidemic.

• Pilgrims undertaking Hajj and Umrah must have the meningococcal ACWY vaccine in order to obtain their visa for entry into Saudi Arabia. The vaccine must have been given no less than ten days prior to entry into the country and no more than five years ago for the conjugate vaccine. The polysaccharide vaccine must have been given in the last three years, but is not currently available in the UK.⁴

Immunisation planning³

An immunisation programme specific to a traveller's planned journey is essential. This needs to take into account:

• Purpose of trip: eg, holiday, sport, disaster relief work, aid work, research, expedition/adventure. This affects exposure to risk, with aid workings and disaster relief workers particularly exposed to difficult local conditions.

• Length of stay.

• Travel itinerary: place, nature of travel, degree of contact with the local population and/or animals, remoteness/off the beaten track, expected risk-taking behaviour.

• Previous immunisation and infections, previous adverse reactions.

• Contra-indications to specific vaccines or vaccine types (including the possibility of pregnancy in women of reproductive age).

• The patient's co-morbidities, if any, and any medication that they take, including whether they are immunosuppressed and therefore live vaccines are contraindicated.

• Diseases prevalent in the areas of travel and vaccinations available.

• Nature, prevalence and typical location of disease vectors.

• Other preventative options, including malaria prophylaxis.

Having ascertained what vaccinations are needed a schedule is developed covering:

• Mix of live, attenuated and toxoid vaccines needed.

• Recommended timing of vaccination courses. Some immunisations involve a course of injections at specified intervals and it can take up to six months to complete a course. Some immunisations cannot be given together.

Live vaccines may be given either at the same time as one another (and other vaccinations) or with at least four weeks removed from them. This is because there is evidence that, in the period after live vaccination, there is an attenuation of response to other vaccinations, so the concern is regarding vaccine effectiveness rather than danger.³

Other important precautions

Immunisation constitutes only a part of risk reduction against disease acquired when travelling. The protection offered by vaccination is not 100%. The chance of acquiring a disease, once immunised, should be seen as significantly reduced but not removed. Immunity and protection depend on other factors, including individual responses and exposure to pathogenic load. There are also many tropical diseases against which no safe and effective immunisation has been developed.

It is therefore essential that patients are advised on the importance of other protective measures. Equipping patients with appropriate and focused knowledge is an essential part of travel advice. See the separate Advising patients travelling to remote locations article, which also offers suggestions as to medication which patients might take with them on a 'just in case' basis.

Patients also need to be clearly advised on:

• The limitations of protection offered by vaccination.

• The risk and prevention of diseases for which vaccination is not available, including malaria, Zika virus, Ebola virus and HIV. This includes advice on avoiding exposure to insect vectors, on safe sexual practices, on the avoidance of tattoos or exposure to commercial barbers for shaving if needles/razors do not appear to be single use, and on good food hygiene.

• The urgent need to seek medical advice in particular situations even if vaccinated - eg, possible rabies exposure through a dog bite.

Finally, it is important to check that more 'regular' immunisations such as diphtheria, tetanus and acellular pertussis (DTaP) are current. Primary care health professionals should consider surgery and website notices reminding travellers of the need to allow several months prior to long-haul and exotic travel, in order to enable optimum planning.

Special cases

Aid workers

All travelling involves some risk but some travellers are particularly in harm's way. Aid workers and those going into disaster zones are particularly vulnerable to travel-acquired disease. This is because they face close contact with stressed and possibly sick local populations and may themselves be living in difficult or dangerous environments, with breakdown of local systems (such as sanitation) and reduced or absent access to safe water supplies. Such patients should be fully briefed by their aid organisation, if they are travelling with one. Some volunteers are not and it is essential to offer them full and realistic advice on disease prevention. One additional vaccine which might be considered in these groups is varicella for non-immune adults likely to be working with displaced families.

Other more unusual vaccinations which might be recommended in special cases include smallpox and anthrax. The former would only be required if bioterrorism is suspected and, if this were the case, advice would be issued. The latter might be advised in those travelling to help with livestock in areas where the disease is present.³ Anthrax is more common in countries without widespread veterinary or human public health programmes - mainly less-developed countries.

Travellers to remote locations

The separate Advising patients travelling to remote locations article covers the kind of advice that needs to be offered to these travellers. They are often by nature a group who will accept higher risk but it is still essential to offer advice on minimising this risk.³

Travellers visiting family

These patients form a special group in that they may be returning to a country where they were born or grew up and where the family members whom they are visiting have a degree of immunity to local disease. This is particularly true of patients visiting malarial zones, who may assume that because nobody in their malarial zone-dwelling family has had malaria recently then the risk is low.

Such patients may not even attend the surgery before travel and often don't accept that they may need immunisations or malaria prophylaxis in order to visit what they regard as their homeland. Good website advice and posters in the waiting room are an important part of reminding patients that as UK residents any natural immunity they once possessed is long ago lost.

Children

The principles of travel immunisation in children are as for adults: vaccination should be given where the benefits outweigh the risks. Where travel is to unusual, remote and difficult locations then carers should be carefully pressed on the risk/benefit balance for very young children embarking on such trips, particularly children who are too young to be fully immunised.

Many, if not most, travel vaccines are available in paediatric preparations and the contra-indications are generally the same as for adults. Remember too that most children will be only part of the way through the full UK routine immunisation schedule. If risks of specific diseases appear raised by travel then bringing forward planned vaccinations may be sensible.

Children are vulnerable to malaria and should be protected if travelling to malarial zones. Some antimalarials are contra-indicated in children, particularly tetracyclines; also, some come only in tablet form which may mean grinding tablets for very young children. Compliance can be difficult to achieve, as the taste can be extremely unpleasant and if children vomit after taking it, it can be very difficult for parents to know what to do next. See the separate Malaria prophylaxis article.

Older travellers

The immunisation advice for older travellers follows the same principles as those for anyone else. The presence of chronic health conditions may influence the advisability of exotic travel and also affects the vulnerability of the patient to infection. Consider whether patients are on medications which might affect their immunity and therefore their suitability for live vaccines. Impaired renal function is significant for malaria prophylaxis.

The full range of immunisations is available to older travellers, although the usual contra-indications for live vaccines apply. Zoster vaccination and pneumococcal vaccination should also be considered, if they have not already been given.

Pregnant women

Travel in pregnancy carries a slightly increased risk of a number of serious conditions, including thromboembolic disease. Travel in late pregnancy carries the obvious concern that early labour may mean delivery in an unplanned place and early pregnancy travel is compounded by the risk of miscarriage. There is no reason to suppose that the risks of either early labour or miscarriage are increased by travel alone.

However, if the pregnancy appears medically uncomplicated and the airline is willing to fly the patient (most airlines restrict, discourage or even ban flying later than 28 weeks of pregnancy) then there is no reason why pregnant women cannot travel safely.

Pregnant women are nevertheless advised, if possible, to choose holiday destinations for which no vaccination is required. Ideally no vaccines would be given in pregnancy, although inactivated vaccines are believed to be safe.

• No evidence exists of risk to the fetus of inactivated virus or bacterial toxins or toxoids and advice is generally that the benefits of vaccination with these vaccines outweigh the risks where the risk of exposure to the disease is significant.

• There is a concern that live and attenuated bacterial and viral vaccines could directly harm the fetus through in utero infection. This is a theoretical concern and no cases have ever been reported; inadvertent administration of a live vaccine during pregnancy is not an indication for an otherwise unwanted abortion. Live vaccines include BCG, measles, mumps and rubella (MMR - all three components), varicella, yellow fever, rotavirus and oral polio and typhoid vaccines. These should also not be given in the first six months of life to infants born to pregnancy women who were on immunosuppressive biological therapy during pregnancy.

The guidance around travel vaccines in pregnancy is summarised in Chapter 6 of The Green Book:³⁵

Pregnant women are advised against travelling to malarial regions: some antimalarials are not recommended in pregnancy and if pregnant women do develop malaria they are at increased risk of serious disease with complications.⁶

If a pregnant woman has no alternative but to visit a malarial region, the following principles of prophylaxis should be considered:⁶

• Chloroquine is safe in all trimesters.

• Mefloquine can be used in all trimesters for travellers to high-risk areas, otherwise caution is advised in the first trimester.

• Doxycycline is generally avoided in pregnancy, but if all other options are unsuitable and the course will be completed before 15 weeks gestation, it can be considered.

• Atovaquone plus proguanil is usually avoided in pregnancy (due to a lack of data rather than due to evidence of harm) but can be used if no other options are appropriate. Women using this medication who are pregnant or trying to conceive should take 5 mg folic acid daily.

Zika virus is a flaviviral infection transmitted by the bite of the Aedes mosquito. There is currently no vaccine or treatment. Since 2007 it has caused several outbreaks in the Pacific, and a 2015 outbreak in South America has led the WHO to declare a Public Health Emergency of International Concern. The condition resembles dengue fever and is usually mild or asymptomatic; however, it appears to carry a significant risk of birth defects when contracted in pregnancy. The WHO has issued temporary recommendations that pregnant women postpone non-essential travel to areas where there is active transmission. Public Health England's health protection website offers current guidance on which countries have current active Zika virus transmission.⁷ See the separate Zika virus article.

Hajj and Umrah

Every year millions of Muslims travel to Mecca to perform Al Hajj. This is the largest annual pilgrimage in the world and it is obligatory for all Muslims to perform Hajj at least once in their lifetime if they can afford to do so. Hajj occurs from the 10th to 15th day of the 12th month in the Islamic calendar. This calendar is eleven days shorter than the Gregorian calendar, so Hajj moves through the year. The exact dates cannot be determined in advance as they are based on the visibility of the hilal (waxing crescent moon following a new moon) and are based on sightings in Saudi Arabia.

Umrah is a pilgrimage to Mecca, which can be undertaken at any time of year. It is not compulsory but is recommended for all Muslims, at least once in their lifetime.

The Saudi Arabian Ministry of Health publishes health advice on its website for travellers to the Kingdom of Saudi Arabia (KSA) for the purposes of Hajj and Umrah.⁸

Meningococcal ACWY vaccine is mandatory for all travellers entering KSA for Hajj. Seasonal influenza vaccine is recommended. Even if UK travellers are making the journey in the UK summer they will encounter others from areas in the world where influenza is currently prevalent. Pneumococcal vaccine is recommended in at-risk groups, including the over-65s and those with chronic heart or lung conditions, although these groups are in fact currently advised by KSA not to make the journey. Other requirements such as yellow fever vaccination and polio vaccination are placed on travellers coming from certain countries, of which the UK is not one.

Malaria prevention

The separate Malaria prophylaxis article discusses prophylaxis against malaria. People who live permanently in malarial zones have partial protection but they lose this swiftly when they move away. Many patients make the assumption that when travelling back to their country of origin no prophylaxis is needed. Their understanding needs to be checked at the time of travel immunisation planning.

Diseases for which no vaccine is yet available

There are many tropical diseases for which no vaccination is yet available. These include:

• Insect (arthropod)-borne viruses such as Zika, which are becoming increasingly common, with outbreaks in Southern Europe as well as more obviously 'tropical' destinations such as Southeast Asia.

• Rare but devastating viral haemorrhagic fevers such as Ebola virus and Marburg virus, both of which are spread by rats but which are highly contagious in terms of person-to-person transmission.

• Infections carried by water-dwelling organisms such as bilharzia and flukes.

• Parasitic diseases such as leishmaniasis, onchocerciasis, trypanosomiasis and hydatid disease.

• There is also as yet no vaccine against HIV.

• Most of these conditions can be avoided by travellers taking reasonable precautions around:

  • Hygiene.

  • Food and drink.

  • Swimming in water known to be infested with parasitic organisms.

  • Exposure to biting insects.

  • Unprotected sexual encounters.

Payment

The NHS does not usually cover travellers for most vaccinations relating to exotic travel, although typhoid and hepatitis A are exceptions. Payment is usually required for other travel vaccinations and for courses of anti-malarial tablets. The costs can mount up, particularly where several vaccinations and anti-malarial medication are required; however, patients need to be encouraged to regard this as an essential part of their holiday cost and not an optional extra.

Yellow fever vaccination can only be offered by licensed centres where staff have undergone the appropriate training.⁹

Compulsory vaccinations

There are a few countries and situations for which there are compulsory vaccinations such as meningococcal ACWY vaccination for Hajj and yellow fever vaccination for some African countries. Some countries require yellow fever vaccination only when travelling from a country where yellow fever is present but others require it for all travellers. Vaccine certification is only generally required by countries who have a population of Aedes aegypti mosquitoes, to avoid spread of yellow fever from the traveller into the local mosquito population.

Many countries which harbour yellow fever have made significant efforts to eradicate the disease through widespread vaccination. Yellow fever cannot circulate in the insect population in areas where the human population is immune as, like malaria, it cannot complete its whole reproductive cycle in the mosquito.

Further reading

There are many excellent websites offering detailed advice for travellers by country and region. They also offer sensible clear advice on risk avoidance. ²¹⁰¹¹

Dr Mary Lowth is an author or the original author of this leaflet.