# P-1665. Factors associated with seasonal Influenza and COVID-19 booster vaccination in a multicentre Irish healthcare worker cohort

## TL;DR

This study examines factors influencing vaccine uptake among healthcare workers in Ireland, finding that older age, higher education, and prior vaccination history are linked to higher rates of seasonal influenza and COVID-19 booster vaccines.

## Contribution

The study identifies specific demographic and behavioral factors associated with vaccine uptake among healthcare workers in Ireland using a longitudinal cohort.

## Key findings

- Only 37% of healthcare workers received the influenza vaccine and 22% received a COVID-19 booster.
- Older age, higher education, and shorter time since last vaccination were associated with increased vaccine uptake.
- Male healthcare workers were more likely to receive the COVID-19 booster than females.

## Abstract

The use of vaccination against both SARS-CoV-2 and Influenza is an important tool in preventing healthcare workers (HCW) ill-health and nosocomial patient infection. However, vaccine uptake is highly variable. We utilise a longitudinal HCW study to describe uptake of seasonal Influenza and COVID-19 booster vaccines, as well as factors associated with receipt of vaccine.Figure 1:Vaccine uptakeBreakdown of Influenza and COVID-19 vaccine uptakeTable 1:Characteristics associated with receipt of any seasonal vaccineBetween-group differences assessed using Chi-squared or Wilcoxon ranksum test, as appropriate.

Vaccine uptake

Breakdown of Influenza and COVID-19 vaccine uptake

Characteristics associated with receipt of any seasonal vaccine

Between-group differences assessed using Chi-squared or Wilcoxon ranksum test, as appropriate.

All participants in the Prevalence of COVID-19 in Irish HCWs (PRECISE) study, a longitudinal study across two hospital sites in Ireland (St James’s Hospital, Dublin & University Hospital Galway), were included. Participants reported seasonal vaccines received from September 2024 – February 2025, prior vaccine history, and demographic, medical and occupation details. Vaccination history was confirmed using the national immunisation system. Univariate analysis assessed variables associated with both Influenza and COVID-19 vaccine uptake, with multivariable logistic regression including significant univariate variables and relevant variables identified a priori.Table 2:Characteristics associated with COVID-19 booster and seasonal Influenza vaccineBetween-group differences assessed using Chi-squared or Wilcoxon ranksum test, as appropriate.Table 3:Multivariable regression of factors associated with COVID-19 booster and seasonal Influenza vaccineMultivariable models including significant univariate features and variables selected a priori. Time since last vaccine was z-scored prior to analysis.

Characteristics associated with COVID-19 booster and seasonal Influenza vaccine

Between-group differences assessed using Chi-squared or Wilcoxon ranksum test, as appropriate.

Multivariable regression of factors associated with COVID-19 booster and seasonal Influenza vaccine

Multivariable models including significant univariate features and variables selected a priori. Time since last vaccine was z-scored prior to analysis.

There were n=893 participants. Of these, n=549 (61%) did not receive any vaccine, n=189 (21%) received both COVID-19 and Influenza vaccine, n=145 (16%) received Influenza alone and n=10 (1%) received COVID-19 alone (Figure 1). Older age, level of educational attainment, and a shorter interval since most recent vaccination were associated with increased uptake of any vaccine. These variables were associated with both Influenza and COVID-19 vaccine. Additionally, male HCWs were more likely to receive the COVID-booster than females, while there were no sex differences with Influenza vaccine uptake (Table 2). These variables remained significant following multivariable logistic regression (Table 3).

The overall uptake of vaccination amongst HCWs is low, with 37% receiving Influenza vaccine and fewer than 1 in 4 (22%) receiving a COVID-19 booster. Older age, education status and prior engagement with vaccine programmes influenced vaccine uptake. COVID-19 vaccination was significantly lower in female HCWs. These factors should inform future vaccination information campaigns to improve vaccine coverage.

All Authors: No reported disclosures