A shrinking world: What the COVID-19 pandemic taught us about travel vaccines in a globalised society

Introduction

In the UK and Ireland, we often think of countries with endemic infectious diseases as far-away locations. This perception can lead us to believe that we are protected from diseases by a physical barrier. Nowadays, however, we can access these countries with greater ease, and the apparent barrier between us and diseases has become even more insignificant. 

This ’shrinking world’ was starkly demonstrated by the COVID-19 pandemic. Despite global efforts to contain the disease—travel restrictions, periods of lockdown, and isolation—the SARS-CoV-2 virus rapidly spread across the globe. With the world now returned to pre-pandemic levels of tourism, what lessons can we learn about infectious disease management?

The many travel vaccines which are readily available allow people to access countries whilst protecting themselves and others against infectious diseases. Post-COVID, the importance of vaccination against infectious diseases to improve the population general health has become even clearer. Alarmingly, research shows that not everyone who travels internationally receives the advised vaccinations^​1​. We face a unique opportunity to increase awareness of travel-related diseases and improve the uptake of vaccinations. This will allow us to continue safe, responsible movement throughout our globalised society. 

In this white paper, we aim to address the question: “What is the relationship between international travel and travel vaccines?”. To do this, we will consider:

1. What are travel vaccines?
2. The economic benefits of tourism to countries with vaccine-preventable disease
3. The relationship between travel vaccines and international travel in the post-COVID world.

1. What are travel vaccines?

The NHS’s routine vaccination schedule protects the population against several diseases but does not cover all the infectious diseases found overseas^​2​. Nowadays, we travel internationally much more, and so we are more likely to encounter serious infections that are not common at home^​3​. The risk of becoming ill when travelling to low- and middle-income countries is estimated to be between 47% and 79%^​4,5​. This risk varies depending on the infectious disease, destination and length of stay, as well as the general hygiene of travel conditions and traveller’s general health^​3,6​. 

Of course, it is not only the traveller who may become ill. The COVID-19 pandemic showed just how easily diseases can spread, even without travelling. It is, therefore, important to raise awareness of the individual responsibility to reduce the risk of catching an infectious disease as it may spread further and cause disease outbreaks when returning to the home country. 

Travel vaccines are highly effective at protecting from illness and stopping the spread of some infectious diseases, including cholera, diphtheria, hepatitis A and B, rabies, tetanus, tuberculosis, typhoid and yellow fever^​6​. Up-to-date travel advice may be sought from the World Health Organization^​6​, and, in the UK, from the NHS website^​2,7​. It is important to personalise the plan based on traveller’s vaccination history and general health, travel destination and the time remaining before departure^​6​. 

Common vaccines for international travellers are shown in Figure 1. Travel vaccines are advised when travelling to some countries to protect us from travel-related illnesses but may not be a requirement for entry into the country^​6​. For other countries, it is required to show proof of travel vaccination (e.g., for yellow fever) before being even allowed to enter or exit the country^​6​.

2. The economic benefits of tourism to countries with vaccine-preventable disease

Countries with endemic infectious diseases are often far-away locations from the UK and used to be largely inaccessible. However, long-haul air travel has revolutionised international travel. In 2018, there were around 1.4 billion international arrivals by tourists globally^​4,8​. International travellers and tourists spent US$1.8 trillion worldwide in 2019^​9​. Clearly, this is a major boost to developing countries, as tourism is often very important for their economies^​10​. 

There have been several notable disease outbreaks in recent decades, including the 2003 severe acute respiratory syndrome (SARS) outbreak and the 2015 Middle East respiratory syndrome (MERS) outbreak. The tourism sector survived both outbreaks without a long-term decline in global tourism^​11​. However, travel restrictions in 2020 due to COVID-19^​11​ heavily affected the travel and tourism industry^​12​, which suffered a loss of almost US$4.9 trillion (a 50.4% decline) and 62 million jobs (a 18.6% decline) from 2019 (Figure 2)^​9​. 

Nowadays, many people are rethinking their approach to international travel and are more aware of serious travel-related infections^​13,14​. Travel vaccines may, therefore, play a crucial role in sustaining tourism and economic welfare in developing countries by allowing people to travel safely and responsibly to countries with endemic infectious diseases^​15,16​. Recent research showed that vaccination against COVID-19 increased the probability of people taking a holiday trip^​17​.

3. The relationship between travel vaccines and international travel in the post-COVID world

How many people travel without travel vaccines?

Data show that many travellers receive their travel vaccinations and are safely protected from travel-related illness during their journey^{​18–24​}.

There are many reasons why travellers showed a positive attitude towards receiving travel vaccinations — these are summarised in the top half of Figure 3. Research shows that many people agree on the benefits of travel vaccines in helping them to stay healthy — across four studies, 74–92% of travellers agreed that travel vaccines provided essential protection from travel illness^{​18,19,22,25​}. For other people, travelling with work, or the need to obtain proof of travel vaccinations, often reminds them to receive their travel vaccinations^​22,24​. During the COVID-19 pandemic, the need to provide proof of COVID‑19 vaccination when travelling put a focus on travel vaccines. Research during the pandemic also showed that people who wanted to travel more had a higher intention to get vaccinated against COVID-19^​16​.

Despite this, not all travellers — and sometimes only a minority — receive their travel vaccinations^{​18,19,22,25​}. Not receiving travel vaccines leaves people at risk of serious illness and further spread of diseases during their journey and when they return home, thus potentially exposing the most vulnerable to the risk of contracting the disease and developing more severe complications. These results raise the question: why do people travel without appropriate vaccination and risk their own health and the health of others?

Why do some people travel without appropriate vaccination?

There are many reasons why people choose to travel without travel vaccinations– these are summarised in the bottom half of Figure 3. These reasons include concerns about the safety of travel vaccines, a lack of knowledge about travel-related diseases, a perception that there is a low risk of infection, cost, fear of needles, and an overall negative attitude towards vaccines^{​18–20,24,26–28​}.

Vaccine safety has highlighted an important concern for many travellers, despite travel vaccines having been shown to be generally well tolerated. A conversation on the risk/benefits of vaccination would support travellers to make an informed decision^​24​. Even when vaccines aren’t required for travel, a travel health risk assessment is still recommended for children and older people, pregnant women, and for those who have a weakened immune system or long-term conditions that need medications^​29​. Travellers should be advised to plan ahead and consult their GP or a private travel clinic 4–8 weeks before departure^​2,6​. This will allow sufficient time to complete the vaccination schedules and develop immunity^​2,6​. Even in cases when the trip is imminent, it is not too late to provide pre-travel advice and possibly administer some vaccinations^​6​. 

Summary

Nowadays, travel is more commonplace than ever. For developing countries, this comes as a major boost, as tourism is often vital for their economies. However, as the world becomes a smaller place, the risk of endemic infectious diseases spreading globally is ever more apparent. As COVID-19 showed, this risk of disease spread is present and travel may be a crucial element to facilitate it.

Following the COVID-19 pandemic, many people are rethinking their approach to international travel. Travel vaccines are highly effective at protecting us against vaccine-preventable diseases and play a key role in allowing people to safely access many countries with endemic infectious disease. Now, more than ever, appropriate vaccination should be a routine consideration when travelling abroad. Despite the wide availability and benefits of travel vaccines, many individuals travel without them, ultimately risking their own health, as well as disease spread in the community, including their local community. There is an urgent need to increase awareness amongst the public and healthcare professionals of travel-related diseases and vaccinations to increase the uptake of travel vaccinations and help maintain safe, responsible international travel.