Longitudinal assessment of influenza vaccination coverage in Spain: The “Gripómetro” as a real-time monitoring tool

Delayed availability of vaccine coverage statistics can limit within-season situational awareness for seasonal influenza vaccination campaigns. This longitudinal ecological study evaluated influenza vaccination coverage (IVC) in Spain across five seasons (2018/19 to 2022/23) using the real-time monitoring tool Gripómetro, based on weekly landline telephone interviews conducted for six consecutive weeks starting 14 d after campaign launch. Adults aged 18-80 y from the Spanish population and healthcare workers (HCWs) from public primary care centers were surveyed using a semi-structured questionnaire. An overall IVC increase was observed during the COVID-19 pandemic, peaking in the 2020/21 season. Among individuals aged ≥65 y, coverage rose from 56% in 2018/19 to 68% in 2020/21 and remained stable thereafter, below the European stablished target 75%. In 2020/21, a coverage peak (49%) was observed among at-risk adults <65 y, followed by a decline. HCWs achieved 74% IVC during the pandemic, with a smaller decline in subsequent seasons. Despite increased coverage, ~80%-85% of respondents still perceived influenza as a mild illness. However, adherence improved over time, with more participants identifying as "Faithful" to vaccination and fewer as "Not convinced." The Gripómetro provided early, within-season coverage estimates that closely tracked official national data for older adults and can complement delayed administrative reporting. The findings highlight the positive influence of the pandemic on vaccination uptake, and the importance of sustained public health efforts to maintain influenza risk awareness and preserve high IVC.