Impact of influenza vaccination programmes among the elderly population on primary care, Portugal, Spain and the Netherlands: 2015/16 to 2017/18 influenza seasons

Abstract

Background:To increase the acceptability of influenza vaccine, it is important to quantify the overall benefits of the vaccination programme. Aim: To assess the impact of influenza vaccination in Portugal, Spain and the Netherlands, we estimated the number of medically attended influenza-confirmed cases (MAICC) in primary care averted in the seasons 2015/16 to 2017/18 among those ≥ 65 years. Methods: We used an ecological approach to estimate vaccination impact. We compared the number of observed MAICC (n) to the estimated number that would have occurred without the vaccination programme (N). To estimate N, we used: (i) MAICC estimated from influenza surveillance systems, (ii) vaccine coverage, (iii) pooled (sub)typespecific influenza vaccine effectiveness estimates for seasons 2015/16 to 2017/18, weighted by the proportion of virus circulation in each season and country. We estimated the number of MAICC averted (NAE) and the prevented fraction (PF) by the vaccination programme. Results: The annual average of NAE in the population ≥ 65 years was 33, 58 and 204 MAICC per 100,000 in Portugal, Spain and the Netherlands, respectively. On average, influenza vaccination prevented 10.7%, 10.9% and 14.2% of potential influenza MAICC each season in these countries. The lowest PF was in 2016/17 (4.9-6.1%) with an NAE ranging from 24 to 69 per 100,000. Conclusions: Our results suggest that influenza vaccination programmes reduced a substantial number of MAICC. Together with studies on hospitalisations and deaths averted by influenza vaccination programmes, this will contribute to the evaluation of the impact of vaccination strategies and strengthen public health communication.

Estimating averted COVID-19 cases, hospitalisations, intensive care unit admissions and deaths by COVID-19 vaccination, Italy, January−September 2021

“…We focused on data covering the population aged 12 years and older, for the period between 11 January (week 2) and 30 September (week 38) 2021. The weekly number of COVID-19 cases, hospitalisations, ICU admissions and deaths averted by the vaccination campaign was estimated using a method widely used in the study of the impact of the vaccination during the influenza season [ 11 , 12 ] and recently applied to calculate vaccine-prevented COVID-19 deaths [ 13 ]. Details can be found in the Supplementary Material 2 .…”

Absence of association between 2019‐20 influenza vaccination and COVID‐19: Results of the European I‐MOVE‐COVID‐19 primary care project, March‐August 2020

“…In the 2020‐21 winter season with the ongoing COVID‐19 pandemic, it is crucial to reduce the burden on hospitals, as much as possible. Influenza vaccination, despite its sometime moderate vaccine effectiveness, is an important factor in reducing hospitalisations 5 and is specifically important for the 2020‐21 season with SARS‐CoV‐2 circulation.…”

Understanding the Influence of Individual and Systemic Factors on Vaccination Take-Up in European Citizens Aged 55 or Older

“…Further country characteristics like general trust in authorities [ 12 ], national vaccination campaigns [ 5 , 13 ] or doctors’ quality [ 14 ] might play a large role in determining vaccination behavior and are captured by the inclusion of country dummies. In addition, we are interested whether more general aspects like the organization of the health care system influences vaccination uptake.…”

“…Vaccinations are recommended by the European Centre for Disease Prevention and Control (ECDC) and various national and international medical societies, even when the vaccination strategies vary by a certain degree in different countries of the European Union (EU) [ 3 ]. The benefits of vaccination for the public health have been demonstrated repeatedly in numerous high-quality studies [ 4 , 5 ]. In the scientific community and in the public sphere vaccines are generally viewed as both effective and safe.…”