BackgroundClinically vulnerable groups are at greater risk of serious illness when seasonal flu and increased COVID-19 infection rates coincide. Public Health Wales ran a national Winter Respiratory Vaccines Communications Campaign in 2022-23, jointly targeting flu and COVID-19 vaccination uptake, tailoring messages towards low uptake groups, and eligible groups with underlying health conditions. We evaluated whether the campaign increased vaccination uptake in the clinically vulnerable using a natural experiments approach. MethodsThe study used a total population of patients registered with NHS Wales during Sept 1 to Dec 31, 2022, who were eligible for both flu and COVID19 vaccination. Anonymised data from the National Vaccination Registry in the SAIL databank was analysed using a controlled interrupted time series (CITS) to investigate the impact of the campaign on vaccine uptake. Due to the availability of data before the beginning of the campaign, COVID-19 daily rates of vaccination were used. The campaign intervention group contained respiratory clinically vulnerable patients aged 16–49 years (n=49 749) and the control group was patients not clinically vulnerable but eligible because of age ≥50 years. The preintervention time series was 1 to 26 September 2022 and post campaign data was examined in the initial weeks after campaign introduction. Modelling will take account of COVID-19 infections, vaccination invitation letters and consider demographics. FindingsDescriptive trends in vaccination uptake show age is a dominating factor over clinical risk for people taking up the vaccine offer, particularly as age rises towards 65+ years. Early findings from the CITS suggest an increase in vaccination uptake from the campaign. InterpretationWe outline the practical application of using novel methods to evaluate the impact of a national communications campaign on vaccine uptake. Confidently attributing the effect of the campaign is challenging due to the complex vaccination delivery landscape, with results requiring careful interpretation. FundingNone.
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