Low effectiveness of seasonal influenza vaccine in preventing laboratory-confirmed influenza in primary care in the United Kingdom: 2014/15 mid–season results

Abstract

In 2014/15 the United Kingdom experienced circulation of influenza A(H3N2) with impact in the elderly. Midseason vaccine effectiveness (VE) shows an adjusted VE of 3.4% (95% CI: −44.8 to 35.5) against primary care consultation with laboratory-confirmed influenza and −2.3% (95% CI: −56.2 to 33.0) for A(H3N2). The low VE reflects mismatch between circulating viruses and the 2014/15 northern hemisphere A(H3N2) vaccine strain. Early use of antivirals for prophylaxis and treatment of vulnerable populations remains important.