Influenza vaccination coverage rates in the UK: a comparison of two monitoring methods during the 2002-2003 and 2003-2004 seasons

OBJECTIVES: To assess the feasibility of measuring influenza vaccination coverage during 2002-2003 and 2003-2004 seasons using a telephone survey; to compare these findings with routine vaccine uptake monitoring based on data provided by general practitioners. STUDY DESIGN: Telephone-based survey. METHODS: We interviewed a random sample of non-institutionalized individuals representative of the population aged 16 years and over. Four target groups were determined for analysis: (1) people aged 65 years and over; (2) healthcare workers; (3) people under 65 years with chronic illnesses, which placed them at risk for influenza; and (4) a group composed of all three previous groups combined. RESULTS: The overall sample consisted of 4054 people (about 2000 per season). Population influenza vaccine coverage in the UK increased from 22.3% in 2002-2003 to 24.2% in 2003-2004. Vaccine uptake was strongly age dependent, even in people aged 65 years and over (the ages at which all people are routinely targeted). In both seasons, the estimates of vaccine uptake in people aged 65 years and over were remarkably consistent with those obtained through routine monitoring. Vaccine uptake in healthcare workers was markedly suboptimal. CONCLUSIONS: In the UK, a telephone-based system of monitoring influenza vaccine uptake seems robust enough to generate data that are comparable with routine vaccine monitoring undertaken using data provided by general practitioners. Although such a system cannot easily contribute towards monitoring of vaccination at local and regional levels, it offers a validated method of estimating vaccine uptake that is independent of healthcare workers' time. This may be especially important for a pandemic vaccination programme, especially in countries in which healthcare resources are scarce, or where the configuration of healthcare services is less conducive to internal monitoring than is the case in the UK