The Journal of Infectious Diseases MAJOR ARTICLE
Influenza Vaccine Effectiveness Against 2009 Pandemic Influenza A(H1N1) Virus Differed by Vaccine Type During 2013–2014 in the United States Manjusha Gaglani,1 Jessica Pruszynski,1 Kempapura Murthy,1 Lydia Clipper,1 Anne Robertson,1 Michael Reis,1 Jessie R. Chung,3,a Pedro A. Piedra,2 Vasanthi Avadhanula,2 Mary Patricia Nowalk,4 Richard K. Zimmerman,4 Michael L. Jackson,5 Lisa A. Jackson,5 Joshua G. Petrie,6 Suzanne E. Ohmit,6 Arnold S. Monto,6 Huong Q. McLean,7 Edward A. Belongia,7 Alicia M. Fry,3 and Brendan Flannery3 1 Baylor Scott & White Health, Texas A&M Health Science Center College of Medicine, Temple, and 2Baylor College of Medicine, Houston, Texas; 3Centers for Disease Control and Prevention, Atlanta, Georgia; 4University of Pittsburgh, Pennsylvania; 5Group Health Research Institute, Seattle, Washington; 6Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor; and 7 Marshfield Clinic Research Foundation, Wisconsin
(See the editorial commentary by Pavia on pages 1521–2.)
Background. The predominant strain during the 2013–2014 influenza season was 2009 pandemic influenza A(H1N1) virus (A[H1N1]pdm09). This vaccine-component has remained unchanged from 2009. Methods. The US Flu Vaccine Effectiveness Network enrolled subjects aged ≥6 months with medically attended acute respiratory illness (MAARI), including cough, with illness onset ≤7 days before enrollment. Influenza was confirmed by reversetranscription polymerase chain reaction (RT-PCR). We determined the effectiveness of trivalent or quadrivalent inactivated influenza vaccine (IIV) among subjects ages ≥6 months and the effectiveness of quadrivalent live attenuated influenza vaccine (LAIV4) among children aged 2–17 years, using a test-negative design. The effect of prior receipt of any A(H1N1)pdm09-containing vaccine since 2009 on the effectiveness of current-season vaccine was assessed. Results. We enrolled 5999 subjects; 5637 (94%) were analyzed; 18% had RT-PCR–confirmed A(H1N1)pdm09-related MAARI. Overall, the effectiveness of vaccine against A(H1N1)pdm09-related MAARI was 54% (95% confidence interval [CI], 46%–61%). Among fully vaccinated children aged 2–17 years, the effectiveness of LAIV4 was 17% (95% CI, −39% to 51%) and the effectiveness of IIV was 60% (95% CI, 36%–74%). Subjects aged ≥9 years showed significant residual protection of any prior A(H1N1)pdm09containing vaccine dose(s) received since 2009, as did children
Influenza Vaccine Effectiveness Against 2009 Pandemic Influenza A(H1N1) Virus Differed by Vaccine Type During 2013–2014 in the United States Manjusha Gaglani,1 Jessica Pruszynski,1 Kempapura Murthy,1 Lydia Clipper,1 Anne Robertson,1 Michael Reis,1 Jessie R. Chung,3,a Pedro A. Piedra,2 Vasanthi Avadhanula,2 Mary Patricia Nowalk,4 Richard K. Zimmerman,4 Michael L. Jackson,5 Lisa A. Jackson,5 Joshua G. Petrie,6 Suzanne E. Ohmit,6 Arnold S. Monto,6 Huong Q. McLean,7 Edward A. Belongia,7 Alicia M. Fry,3 and Brendan Flannery3 1 Baylor Scott & White Health, Texas A&M Health Science Center College of Medicine, Temple, and 2Baylor College of Medicine, Houston, Texas; 3Centers for Disease Control and Prevention, Atlanta, Georgia; 4University of Pittsburgh, Pennsylvania; 5Group Health Research Institute, Seattle, Washington; 6Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor; and 7 Marshfield Clinic Research Foundation, Wisconsin
(See the editorial commentary by Pavia on pages 1521–2.)
Background. The predominant strain during the 2013–2014 influenza season was 2009 pandemic influenza A(H1N1) virus (A[H1N1]pdm09). This vaccine-component has remained unchanged from 2009. Methods. The US Flu Vaccine Effectiveness Network enrolled subjects aged ≥6 months with medically attended acute respiratory illness (MAARI), including cough, with illness onset ≤7 days before enrollment. Influenza was confirmed by reversetranscription polymerase chain reaction (RT-PCR). We determined the effectiveness of trivalent or quadrivalent inactivated influenza vaccine (IIV) among subjects ages ≥6 months and the effectiveness of quadrivalent live attenuated influenza vaccine (LAIV4) among children aged 2–17 years, using a test-negative design. The effect of prior receipt of any A(H1N1)pdm09-containing vaccine since 2009 on the effectiveness of current-season vaccine was assessed. Results. We enrolled 5999 subjects; 5637 (94%) were analyzed; 18% had RT-PCR–confirmed A(H1N1)pdm09-related MAARI. Overall, the effectiveness of vaccine against A(H1N1)pdm09-related MAARI was 54% (95% confidence interval [CI], 46%–61%). Among fully vaccinated children aged 2–17 years, the effectiveness of LAIV4 was 17% (95% CI, −39% to 51%) and the effectiveness of IIV was 60% (95% CI, 36%–74%). Subjects aged ≥9 years showed significant residual protection of any prior A(H1N1)pdm09containing vaccine dose(s) received since 2009, as did children
