Influenza vaccination, inverse care and homelessness: cross-sectional survey of eligibility and uptake during the 2011/12 season in London.

Background: Influenza vaccination eligibility and uptake among homeless adults has not been previously assessed in the UK. This cross-sectional survey aimed to measure the proportion of homeless people visited by an NHS outreach service (Find and Treat) who were eligible for and had received vaccination during 2011/12.

Methods: A cross-sectional survey was carried out in 27 separate homeless hostels, day centres and drug services in London between July and August in 2012. Eligibility for the survey was by virtue of being in attendance at one of 27 venues visited by Find and Treat. No specific exclusion criteria were used.

Results: 455 clients took part in the survey out of 592 approached (76.9%). A total of 190 homeless people (41.8%; 95% CI: 34.5,50.5) were eligible for influenza vaccination. In those aged 16-64, eligibility due to clinical risk factors was 38.9% (95% CI: 31.5,48.2). Uptake of vaccination in homeless 16-64 year olds with a clinical risk factor during the 2011/12 influenza season was 23.7% (95% CI: 19.8,28.3) compared to national levels of 53.2% (excluding pregnant women). In those aged over 65, uptake was 42.9% (95% CI: 16.7,100.0) compared with 74.0% nationally.

Conclusions: This study demonstrates that the homeless population have high levels of chronic health problems predisposing them to severe complications of influenza, but vaccine uptake levels that are less than half those seen among eligible GP patient groups in England. It provides a clear example of the health inequalities and inverse care law that impact this population. The results of this study provide strong justification for intensifying efforts to ensure homeless people have access to influenza vaccination.