Numerous surveys identify that travellers considerably underestimate the risks associated with travel to developing countries and a subsequent lack of preparation to avoid infectious disease risks [16–22]. This is especially true for younger travellers, who are disproportionately represented in studies assessing infectious symptoms post-travel [23–31]. For example, the incidence of post-travel illness in Swedish travellers who had attended a travel clinic for pre-travel health advice was greatest in those aged 10-24 years (65%) compared to those aged 25-49 years (49%) and those aged 50 years or more (33%) . Younger travellers are at greater risk of infectious diseases which have been attributed to a higher susceptibility, particularly to vaccine-preventable diseases and greater exposure due to increased risk taking behaviours and travel to high-risk destinations [9, 32]. Our study found a low risk perception across all of the health threats, for both domestic and international students, which support the previous findings of USA study abroad students . Students in our study perceived a low personal likelihood of health threats occurring both in Australia and while travelling. The lowest likelihood and worry scores were for the individual infectious diseases included in the survey; dengue, hepatitis A, hepatitis B and measles, despite the fact that they are commonly reported in travellers . Despite more than a third of students reporting that a hepatitis A or dengue infection would 'extremely affect' their health, the majority of students were barely worried. In a Finnish study of risk taking behaviours during travel, willingness to take health risks were associated with younger age , which may partially explain our results. Consistent low risk perceptions were also illustrated in a Canadian study on the beliefs and attitudes of students towards measles immunisations. In that study, 67% of students with no immunity to measles perceived little or no risk of acquiring measles and no need to be immunised for the disease .
In addition to low risk perception, was the low pre-travel preventative health preparation undertaken by our young, globally mobile student population. Uptake of pre-travel health advice was low overall with 68% of respondents reporting they had not sought any advice from a health professional prior to their last international trip. Our international students were far less likely to seek pre-travel advice from a health professional compared to their domestic counterparts. In the few studies that are available on student travellers, it is apparent that a large proportion of students do not seek health advice prior to travel [14, 36]. For example, Abdullah et al reported that only 25% of Hong Kong students had sought pre-travel health advice, with 41% seeking information from 'non-expert' sources . While it is likely that the level of pre-travel assessment and preparation will differ for students by destination (i.e. high vs low risk countries) and prior travel experience; travel consultation may still be required. For example, many young adult Australians are at risk of measles infection. In the past few years there have been several large and ongoing outbreaks of measles in a number of countries in Europe as well as in New Zealand and also several large outbreaks of mumps in the USA in educational institutions . Given that many students are not aware of their immunisation status and many will travel during their university years (including multi-country trips to both high and low risk destinations), pre-travel consultation for this age group may increase awareness of destination-specific risks and provide protection for a lifetime of travel.
We also identified that there were variances amongst our participants in regards to the level of knowledge about travel-related diseases and their personal vaccination histories. Only one in two students were able to correctly identify the availability of the hepatitis A vaccine and more than one in five incorrectly reported that a vaccine for dengue existed. In addition, more than one in ten indicated that they did not know whether they had been previously vaccinated against measles, hepatitis A, hepatitis B and influenza. These deficits in knowledge are consistent with past studies of the general travelling population in which travellers are either unaware of their own immunisation status or have significant misimpressions of their vaccine history .
Gaps in knowledge of personal susceptibility and vaccination status may result in many travellers, including student travellers, choosing to forgo pre-travel vaccination assessments despite lack of existing immunity .
The reported uptake of vaccines was slightly higher amongst our participants than the rates reported by two previous studies. The first study by Hartjes et al. of USA study abroad students found that 42% had received at least one travel vaccine despite students studying in low income countries highly endemic for many vaccine-preventable diseases . Lower uptake rates were reported in a Canadian study of tertiary education students, with 34.4% reporting a history of hepatitis A vaccination, despite 60% reporting prior travel and 81% reporting intention to travel to hepatitis A endemic countries . Few travellers, including young adults, are able to accurately recall prior vaccination and information on vaccination coverage for university age Australians is not easily attainable. Australia has a vaccine registry but it is restricted to vaccines received prior to 7 years of age and to Australian's born during or since 1996. Australian children are registered on the Australian Childhood Immunisation Registrar (ACIR) upon registration with Medicare (99% of Australians) and can be added to the register by their health provider (including migrants) at anytime up to 7 years of age . However, no register exists for older age groups in Australia and while there has been debate around the inclusion of a "whole-of-life" immunisation register,  no definitive actions have been undertaken. From 2013 onwards, Australian-born students or migrants (arriving prior to age 7) entering University in Australia will have been registered on the ACIR and vaccines received up to 7 years of age will be available to registered providers. In future cohorts of commencing university students, access to national vaccine registers may assist providers of travel health advice in determining missed childhood vaccinations and identifying at-risk young adults prior to travel. Other options for determining the vaccination status of international students is required.
Currently, there are no existing requirements at universities in Australia regarding proof of immunisation and status may only be reviewed if the student presents for a consultation. Education institutions may be the last opportunity to capture young adults in vaccination programs and universities clinics may provide the ideal opportunistic environment to improve vaccine coverage and thereby reduce travel risks. However, only 9 international and 15 domestic students indicated that they had attended the University Health Clinic, highlighting an under-utilised domain for travel health provision. Alternatively, education campaigns targeting young adults could also utilise the university networks and information gateways, such as distributing information brochures at the time of enrolment, during orientation week or through university-wide emails and newsletters. Other mediums favoured by young adults such as popular internet sites should also be considered as a possible means of information provision to this susceptible cohort and in increasing uptake of pre-travel preventative health advice. UNSW has embraced technology with campus information being delivered via Twitter and YouTube, while urgent SMS messaging, Facebook, Yammer and other similar sites could also be utilised. Given that the bulk of University community is under 25 years old it is an entirely appropriate to use this new technology.
Despite the university-wide broadcast of the survey and the obtained sample size being sufficiently large to draw statistical conclusions on the total UNSW population, the generalizability of our study is limited by the low response rate obtained. Our survey relied on a convenience sample, and as such may not be representative of the entire student population due to self-selection bias. However, information provided to students on the nature of the study prior to participation did not describe travel health or immunisation, but rather risk perceptions and practices towards infectious diseases in general and therefore may have reduced the opportunity for self-selecting by the students who have an interest in travel health or vaccination. Cross-sectional surveys, by their nature, are subject to recall bias. In this study, we asked students to describe their last episode of travel (undertaken in the previous year). Retrospective self-report of travel behaviours may have resulted in recall bias, contributing to the higher reported uptake rates.