Coverage and missed opportunities for routine vaccination in adult travellers: a single-centre observational study

Reducing missed opportunities for vaccination (MOV) - healthcare encounters in which recommended vaccinations are not given - is a WHO priority. In high-income countries like Australia, adult coverage for routine vaccines remains suboptimal. Specialist travel clinics frequently see medically complex travellers at increased risk of diseases like influenza, pneumococcal disease and shingles, yet may be underutilised for routine vaccination. This study aimed to assess routine vaccine coverage, on-site vaccination and MOV among adult travellers.

Single-centre retrospective observational study of adults attending a hospital-based specialist travel clinic between 1 January and 31 December 2024. Electronic medical records were used to extract demographics, clinical characteristics, vaccination history and serology. Vaccination coverage at initial review was assessed for influenza, pneumococcal, zoster, COVID-19 and MMR vaccines. On-site vaccination and MOV were assessed for influenza, pneumococcal and zoster vaccines only. Descriptive analysis and multivariable logistic regression explored predictors of MOV.

Among 252 patients (mean age 47, 131/252 [52%] female), 43.2% (109/252) were immunocompromised and 33.3% (84/252) were seen via telehealth. At initial clinic review, the proportion up-to-date with recommended vaccination was 63.5% (160/252) for influenza, 54.6% (59/108) for pneumococcal, 27.5% (41/149) for zoster, 34.9% (88/252) for COVID-19, and 66.2% (133/201) for MMR. MOV occurred in 52.9% (119/225) of patients. Immunocompromised patients had increased odds of MOV ([aOR] 2.59; 95% CI 1.39-4.81; p = 0.003).

Routine vaccination coverage among adult travellers was suboptimal, with frequent MOV, particularly among immunocompromised travellers. Specialist travel clinics represent an underutilised opportunity to strengthen routine vaccination in targeted populations.