Navigating a Smaller World: Lessons on Travel Vaccines from the COVID-19 Pandemic

Introduction

In the UK and Ireland, we commonly perceive nations with endemic infectious illnesses as distant regions. This viewpoint can lead us to assume that we are shielded from diseases by a physical obstruction. In the present day, however, we are able to reach these countries with more convenience, and the once-clear barrier between us and pathogens has diminished significantly.

This ‘shrinking world’ was vividly illustrated by the COVID-19 pandemic. In spite of worldwide attempts to control the illness—such as travel limitations, lockdown phases, and quarantines—the SARS-CoV-2 virus swiftly disseminated worldwide. With global travel levels now restored to pre-pandemic conditions, what insights can we gain regarding the management of infectious diseases?

The various travel vaccines that are widely accessible enable individuals to visit nations while safeguarding themselves and others from infectious ailments. Post-COVID, the significance of immunization against infectious diseases to enhance public health has become even more evident. Alarmingly, studies indicate that not every international traveler receives the recommended vaccinations^​1​. We are presented with a distinct opportunity to bolster awareness of travel-associated diseases and improve the acceptance of vaccinations. This will empower us to maintain safe, responsible mobility in our globalized community.

In this white paper, we seek to explore the inquiry: “How does international travel relate to travel vaccines?”. To this end, we will examine:

1. What are travel vaccines?
2. The economic advantages of tourism for nations with vaccine-preventable diseases
3. The connection between travel vaccines and international travel in the post-COVID era.

1. What are travel vaccines?

The NHS’s standard vaccination program safeguards the public against various diseases but does not encompass all the infectious illnesses present abroad^​2​. Given the increased frequency of international travel, we are consequently at a higher risk of encountering severe infections that are rare at home^​3​. The likelihood of falling ill while visiting low- and middle-income countries is estimated to range from 47% to 79%^​4,5​. This risk fluctuates based on the specific infectious disease, destination, duration of stay, as well as the overall sanitary conditions of travel and the traveler’s health status^​3,6​.

Naturally, it is not solely the traveler who can fall ill. The COVID-19 pandemic highlighted just how swiftly diseases can spread, even without travel. Therefore, it is crucial to foster awareness of the individual duty to mitigate the risk of contracting an infectious disease as it could proliferate and trigger disease outbreaks upon returning to one’s home country.

Travel vaccines are extremely effective at providing protection from illness and preventing the transmission of certain infectious diseases, including cholera, diphtheria, hepatitis A and B, rabies, tetanus, tuberculosis, typhoid, and yellow fever^​6​. Current travel guidance can be obtained from the World Health Organization^​6​, and, within the UK, from the NHS website^​2,7​. It is essential to customize the vaccination plan according to the traveller’s immunization history, health status, travel destination, and the duration remaining before travel^​6​.

Common vaccines for global travelers are displayed in Figure 1. Travel vaccines are recommended when visiting certain countries to protect against illnesses related to travel but might not be mandatory for entry into the country^​6​. In contrast, for other nations, it is necessary to present proof of vaccination (e.g., for yellow fever) before being permitted to enter or exit the country^​6​.

2. The financial advantages of tourism for nations with vaccine-preventable ailments

Nations grappling with endemic infectious diseases are frequently remote areas from the UK and were traditionally quite hard to reach. Nonetheless, long-distance air travel has transformed global travel. In 2018, there were approximately 1.4 billion international tourist arrivals worldwide^​4,8​. International tourists spent US$1.8 trillion globally in 2019^​9​. Evidently, this represents a significant uplift for developing nations, as tourism often plays a crucial role in their economic frameworks^​10​.

Several notable disease outbreaks have occurred in recent decades, including the 2003 SARS (severe acute respiratory syndrome) outbreak and the 2015 MERS (Middle East respiratory syndrome) outbreak. The tourism sector withstood both outbreaks without experiencing a long-term drop in global tourism^​11​. However, travel restrictions in 2020 due to COVID-19^​11​ significantly impacted the travel and tourism sector^​12​, which encountered a loss of nearly US$4.9 trillion (a 50.4% decline) and 62 million jobs (an 18.6% fall) since 2019 (Figure 2)^​9​.

Currently, numerous individuals are reevaluating their perspective on global travel and are becoming increasingly conscious of significant travel-related diseases^​13,14​. Travel vaccinations may thus be pivotal in maintaining tourism and economic health in developing regions by enabling individuals to travel safely and responsibly to nations with endemic infectious ailments^​15,16​. Recent studies indicate that vaccination against COVID-19 heightened the likelihood of individuals undertaking holiday trips^​17​.

3. The connection between travel vaccines and international travel in the post-COVID era

What proportion of individuals travel without receiving travel vaccines?

Data indicates that a considerable number of travelers get their travel vaccinations and are thus effectively shielded from travel-associated illnesses during their journeys^{​18–24​}.

Numerous factors contributed to travelers displaying a positive disposition towards receiving travel vaccinations — these are encapsulated in the upper section of Figure 3. Studies reveal that a significant number of individuals recognize the advantages of travel vaccines in assisting them to maintain their health — across four investigations, 74–92% of travelers consented that travel vaccines offered crucial protection against travel illnesses^{​18,19,22,25​}. For others, traveling for work purposes or the necessity to secure verification of travel vaccinations frequently reminds them to obtain their travel vaccinations^​22,24​. During the COVID-19 pandemic, the requirement to present proof of vaccination against COVID‑19 while traveling highlighted the importance of travel vaccines. Research during the pandemic also indicated that individuals who were eager to travel morehad a greater aspiration to receive vaccinations against COVID-19^​16​.

Regardless of this, not every traveler — and at times only a small segment — obtains their necessary vaccinations for travel^{​18,19,22,25​}. Failing to receive travel vaccinations exposes individuals to the risk of severe illness and further transmission of diseases during their travels and upon their return home, thus potentially putting the most susceptible at greater risk of contracting the ailment and experiencing more serious complications. These findings prompt the inquiry: why do individuals travel without the necessary vaccinations and jeopardize their own well-being and that of others?

What are the reasons some travelers forgo appropriate vaccinations?

Numerous factors compel individuals to travel without obtaining vaccinations for travel– a summary of these can be found in the lower half of Figure 3. Concerns surrounding the safety of travel vaccines, lack of awareness regarding travel-related diseases, the belief that the risk of infection is minimal, expenses, fear of injections, and an overall unfavorable perception of vaccines are all contributing reasons^{​18–20,24,26–28​}.

Safety of vaccines has surfaced as a crucial concern for numerous travelers, even though travel vaccines have generally proven to be well tolerated. Engaging in discussions regarding the risks and benefits of vaccination could assist travelers in arriving at a well-informed decision^​24​. Even when vaccines are not mandatory for travel, conducting a travel health risk assessment is advisable for children and the elderly, pregnant individuals, and those with compromised immune systems or chronic conditions requiring medication^​29​. Travelers should be encouraged to prepare in advance and seek advice from their general practitioner or a private travel clinic 4–8 weeks prior to departure^​2,6​. This will provide adequate time to complete vaccination schedules and build immunity^​2,6​. Even when a trip is fast approaching, it remains possible to provide pre-travel guidance and potentially administer certain vaccinations^​6​.

Conclusion

In the present day, traveling has become increasingly common. This serves as a significant advantage for developing nations, as tourism is often crucial for their economic stability. Nevertheless, as the world becomes more interconnected, the threat of endemic infectious diseases spreading worldwide becomes increasingly evident. The COVID-19 pandemic has emphasized that the risk of disease transmission exists, and traveling could be a pivotal component in facilitating it.

In light of the COVID-19 outbreak, many persons are reassessing their views towards international travel. Travel vaccinations are extremely effective in shielding us from diseases that can be prevented through vaccination and are integral in enabling individuals to visit numerous regions with endemic infectious illnesses safely. Now, more than ever, appropriate vaccinations ought to be a standard consideration prior to traveling abroad. Despite the extensive availability and advantages of travel vaccines, numerous individuals still embark on their journeys without them, ultimately endangering their own health and contributing to the spread of diseases within the community, including their local area. There is an imperative need to enhance public and healthcare professionals’ awareness regarding travel-related diseases and vaccinations to promote the acceptance of travel vaccinations and ensure safe and responsible international travel.