Recruitment through travel health advertising: eNewsletters and social media Recruitment will begin through social media and email newsletters to subscribing members. Travel medicine associations with members who subscribe to receive travel health information will post the recruitment script in eNewsletters and on social media websites as part of their normal advertising procedures. When travellers observe the recruitment script in the newsletter or on a social media website, they can click on the link located within it, which will bring them to the study website. If they pass the eligibility criteria, individuals are invited to proceed to complete the recruitment process as described below.