Vaccine-preventable Disease in Older Australian Adults

Abstract

Background: There are limited measures of adult vaccination coverage and factors associated with adult vaccination in Australia. Methods: A systematic review and meta-analysis on influenza and pneumococcal vaccination coverage in Australian adults from 1990-2015 were conducted. Self-reported vaccination data from the 45 and Up Study, a large ongoing prospective cohort study of adults in New South Wales (Australia’s most populous state), were compared to data from the national health insurance scheme, the Medicare Benefits Schedule (MBS) and were subsequently used to investigate vaccination coverage and factors associated with vaccine receipt. A log-binomial model was used to estimate prevalence ratios, adjusted for age and other factors. Results: The systematic review identified 22 studies reporting adult influenza and/or pneumococcal vaccination coverage in Australia. Following introduction of funding, in adults aged > 65 years the summary estimates for influenza and pneumococcal vaccine coverage were 74.8% (95% CI 73.4–76.2%) and 56.0% (95% CI 53.2-58.8) respectively. Limited data for Aboriginal and Torres Strait Islander Australians was available. Linkage of the cohort data with MBS data showed overall agreement on reported influenza vaccination was 70%. Analyses of cohort participants found 67.1% (8576/12779) of those aged > 65 years had an influenza vaccination within the last year whilst 23.5% (16202/68964) reported ever receiving an adult pertussis vaccine. Factors consistently associated with receiving either vaccine were female sex (aPR influenza aPR 1.04 [95%CI 1.02-1.06], pertussis aPR 1.80 [95%CI 1.73-1.86]), non-English speaking country of birth (aPR influenza 0.88[0.83-0.94], pertussis 0.56[0.51-0.63]) and smokers (aPR influenza 0.91[0.84-0.99], pertussis 0.67[0.61-0.75). Receipt of influenza vaccine was more likely in overweight or obese individuals and those with a chronic illness but this was not the case for pertussis vaccine. Conclusion: There are limited data on Australian adult vaccination coverage. Coverage levels found for influenza and pertussis vaccines are sub-optimal and there are sub-groups who could be targeted for vaccination campaigns to improve vaccination.