Identifying people at risk for influenza with low vaccine uptake based on deprivation status: a systematic review

Background: Influenza vaccination is an important public health intervention for controlling disease burden, but coverage rates are still low also in risk groups. In order to identify non-vaccinating subgroups, deprivation and socio-economic indices, i.e. measures used to synthetically describe people's socio-economic status while taking into account several dimensions, may be used. We aimed to synthetize evidence from studies investigating association between deprivation/socio-economic indices and influenza vaccination coverage in population at risk- persons -65 years of age, individuals with comorbidities, pregnant women and health-care workers. Methods: We searched PubMed, ISI WoS, CINAHL and Scopus to identify observational studies published up to October 10th 2017 in English or Italian. Studies reporting quantitative estimates of the association between deprivation/socioeconomic indices and influenza vaccination coverage in populations at risk were included. Results: A total of 1474 articles were identified and 12 were eventually included in the final review. Studies were mostly cross-sectional, performed in European countries, from 2004 to 2017. Seven studies focussed on deprivation and five on socioeconomic indices. Studies on deprivation indices and vaccination coverage showed that people from the most deprived areas had lower coverage. Regarding socio-economic condition, results were contrasting, even though it may also be concluded that people from lower groups have lower vaccination coverage. Conclusions: Our work supports the possibility to identify people likely to have lower influenza vaccination coverage based on deprivation/ socio-economic indices. Efforts should be performed in order to further strengthen robustness, transferability and suitability of these indices in addressing public health problems.