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Effectiveness of H1N1/09 monovalent and trivalent influenza vaccines against hospitalization with laboratory-confirmed H1N1/09 influenza in Australia: A test-negative case control study

Cheng, Allen C., Kotsimbos, Tom, Kelly, Heath A., Irving, Louis B., Bowler, Simon D., Brown, Simon G.A., Holmes, Mark, Jenkins, Christine R., Thompson, Philip, Simpson, Graham, Wood-Baker, Richard, Senanayake, Sanjaya N., Brady, Stephen J., Paterson, David L., Wark, Peter A., Upham, John W., Korman, Tony M., Dwyer, Dominic E., Waterer, Grant W., Kelly, Paul M.
Vaccine 2011 v.29 no.43 pp. 7320-7325
case-control studies, comorbidity, hospitals, influenza, patients, pregnancy, vaccination, vaccines, winter, Australia
We aimed to estimate the effectiveness of H1N1/09 containing influenza vaccines against hospitalization from influenza in Australia. We performed a test-negative case control study in patients hospitalized in 15 sentinel Australian hospitals between March and November 2010, comparing influenza vaccination (H1N1/09 monovalent or 2010 seasonal trivalent) in hospitalized patients with PCR-confirmed influenza compared to PCR-negative controls. Between March and November 2010, 1169 hospitalized patients were tested for suspected influenza, of which influenza vaccine status was ascertained in 165/238 patients with H1N1/09 influenza, 40/64 with seasonal influenza and 558/867 test negative controls; 24% of H1N1/09 cases, 43% of seasonal influenza cases and 54% of controls were vaccinated. VE against hospitalisation with H1N1/09 influenza after adjusting for age, medical comorbidities and pregnancy status was estimated at 49% (95% CI: 13%, 70%). Influenza vaccination was associated with a reduction in hospitalisation caused by H1N1/09 influenza in the 2010 southern hemisphere winter season.