Monitoring influenza vaccination coverage among older adults: a rural cohort study, Rio Grande, 2017-2022

To estimate influenza vaccination coverage in older adults from the municipality of Rio Grande rural cohort, Rio Grande do Sul state, Brazil, using baseline data from 2017 and follow-up data from 2018-2019 and 2020-2022, and to identify factors associated with vaccination uptake during these periods.

This was a cohort study, based on part of the EpiRural Rio Grande project, conducted at three points in time: baseline in 2017 and follow-up in 2018-2019 and 2020-2022. A total of 651 participants aged 60 years or older were included in all waves. Vaccination information was self-reported. Vaccination coverage proportions (%) were estimated at each follow-up point. Analysis of factors associated with vaccination used hierarchical ordinal logistic regression to estimate odds ratios (OR) with 95% confidence intervals (95%CI).

Influenza vaccination coverage increased from 71.5% at baseline to 85.7% in 2020-2022. In the adjusted analysis, the highest odds of vaccination was associated with not working (OR 1.93; 95%CI 1.24; 2.99), not smoking (OR 2.44; 95%CI 1.45; 4.12), being a former smoker (OR 2.71; 95% CI 1.61; 4.59), diagnosis of pulmonary emphysema (OR 1.85; 95%CI 1.04; 3.28), using long-term medication (OR 1.62; 95%CI 1.06; 2.40), and seeking care at a primary health care center in the last year (OR 2.55; 95%CI 1.82; 3.63).

Influenza vaccination coverage increased over time, although below the national target, and was higher among participants linked to health services and with chronic conditions.