Influenza Vaccination Coverage and Determinants of New Vaccinations During the COVID-19 Pandemic in Spain (ENE-COVID): Nationwide Population-Based Study

Abstract

Background: Influenza vaccination coverage is commonly suboptimal. However, the COVID-19 pandemic and consequent high exposure to health information may have changed population attitudes toward this vaccination.

Objective: The aim of this study is to describe influenza vaccine uptake in Spain during the first influenza season following the start of the COVID-19 pandemic compared to the previous one and identify characteristics associated with vaccination among those previously unvaccinated.

Methods: This was a population-based study of 28,987 adults included in influenza vaccination target groups (≥65 years old, with risk conditions, living with someone with risk conditions, health care workers, security or emergency workers) who were participants in the nationwide Seroepidemiological Survey of SARS-CoV-2 Infection in Spain (ENE-COVID) study. Information on vaccination and sociodemographic, health, and COVID-19-related factors was collected by interview. Coverage change from 2019 to 2020 and standardized prevalences of vaccination in 2020 among the population unvaccinated in 2019 were estimated using logistic model-based methods.

Results: Coverage rose from 31.4% (95% CI 30.5%-32.2%) to 46.8% (95% CI 45.8%-47.8%). People ≥65 years old showed the highest uptake in both periods (58.3%, 95% CI 56.8%-59.8% and 74.8%, 95% CI 73.5%-76.1%), while health care workers had the greatest increase (22%, 95% CI 17.8%-26.2%). Among people unvaccinated in 2019, factors associated with vaccination in 2020 were age, female sex, higher education, Spanish nationality, multimorbidity, being a former smoker, obesity, contact with COVID-19 cases, living with older adults, living in provinces with low COVID-19 incidence, wearing a face mask during family meetings, and using surgical/FFP2 masks.

Conclusions: This study provides nationwide representative estimates of influenza vaccination coverage, which clearly increased between 2019 and 2020 in the 5 target groups. However, coverage goals were attained only in the ≥65 year old group, highlighting the importance of reinforcing influenza vaccination. Our detailed results on determinants of vaccination provide some clues to tailor vaccination strategies.

Keywords: COVID-19 pandemic; ENE-COVID; Spain; adult; epidemiology; health information; infection prevention; influenza; influenza prevention; influenza vaccination; influenza vaccine; population-based study; public health; sociodemographic; vaccination; vaccination coverage; vaccination determinants.