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

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Euro Surveill. 2019 Nov;24(45). doi: 10.2807/1560-7917.ES.2019.24.45.1900268. Impact of influenza vaccination programmes among the elderly population on primary care, Portugal, Spain and the Netherlands: 2015/16 to 2017/18 influenza seasons.

Machado A^1,2,3, Mazagatos C^4,2, Dijkstra F^5,2, Kislaya I^1,3, Gherasim A⁴, McDonald SA⁵, Kissling E⁶, Valenciano M⁶, Meijer A⁵, Hooiveld M⁷, Nunes B^1,3, Larrauri A⁴.
Author information

1 NOVA National School of Public Health, Public Health Research Centre, Universidade NOVA de Lisboa, Lisbon, Portugal. 2 These authors contributed equally. 3 National Institute for Health Doutor Ricardo Jorge, Epidemiology department, Lisbon, Portugal. 4 National Centre of Epidemiology, Carlos III Health Institute, CIBER of Epidemiology and Public Health (CIBERESP), Madrid, Spain. 5 National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands. 6 Epidemiology department, Epiconcept, Paris, France. 7 Nivel, Netherlands Institute for Health Services Research, Utrecht, the Netherlands.

Abstract

BackgroundTo increase the acceptability of influenza vaccine, it is important to quantify the overall benefits of the vaccination programme.AimTo 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.MethodsWe 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)type-specific 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.ResultsThe 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.ConclusionsOur 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.


KEYWORDS:

averted cases; impact; influenza; influenza vaccine

PMID: 31718740 DOI: 10.2807/1560-7917.ES.2019.24.45.1900268