Background: The 2009 pandemic influenza A(H1N1) (A[H1N1]pdm09) vaccine component has remained unchanged from 2009. We estimate the effectiveness of current and prior inactivated influenza A(H1N1)pdm09 vaccination from influenza seasons 2010-2011 to 2015-2016. Methods: Patients attended with influenza-like illness were tested for influenza. Four periods with continued A(H1N1)pdm09 circulation were included in a test-negative design. Results: We enrolled 1278 cases and 2343 controls. As compared to individuals never vaccinated against influenza A(H1N1)pdm09, the highest effectiveness (66%; 95% confidence interval, 49%-78%) was observed in those vaccinated in the current season who had received 1-2 prior doses. The effectiveness was not statistically lower in individuals vaccinated in the current season only (52%) or in those without current vaccination and >2 prior doses (47%). However, the protection was lower in individuals vaccinated in the current season after >2 prior doses (38%; P = .009) or those currently unvaccinated with 1-2 prior doses (10%; P < .001). Current-season vaccination improved the effect in individuals with 1-2 prior doses and did not modify significantly the risk of influenza in individuals with >2 prior doses. Conclusion: Current vaccination or several prior doses were needed for high protection. Despite the decreasing effect of repeated vaccination, current-season vaccination was not inferior to no current-season vaccination.
Background: The 2009 pandemic influenza A(H1N1) (A[H1N1]pdm09) vaccine component has remained unchanged from 2009. We estimate the effectiveness of current and prior inactivated influenza A(H1N1)pdm09 vaccination from influenza seasons 2010-2011 to 2015-2016. Methods:Patients attended with influenza-like illness were tested for influenza. Four periods with continued A(H1N1)pdm09 circulation were included in a test-negative design. Results: We enrolled 1278 cases and 2343 controls. As compared to individuals never vaccinated against influenza A(H1N1)pdm09, the highest effectiveness (66%; 95% confidence interval, 49%-78%) was observed in those vaccinated in the current season who had received 1-2 prior doses. The effectiveness was not statistically lower in individuals vaccinated in the current season only (52%) or in those without current vaccination and >2 prior doses (47%). However, the protection was lower in individuals vaccinated in the current season after >2 prior doses (38%; P = .009) or those currently unvaccinated with 1-2 prior doses (10%; P < .001). Current-season vaccination improved the effect in individuals with 1-2 prior doses and did not modify significantly the risk of influenza in individuals with >2 prior doses. Conclusion: Current vaccination or several prior doses were needed for high protection. Despite the decreasing effect of repeated vaccination, current-season vaccination was not inferior to no current-season vaccination.
Authors: Kate Russell; Jessie R Chung; Arnold S Monto; Emily T Martin; Edward A Belongia; Huong Q McLean; Manjusha Gaglani; Kempapura Murthy; Richard K Zimmerman; Mary Patricia Nowalk; Michael L Jackson; Lisa A Jackson; Brendan Flannery Journal: Vaccine Date: 2018-02-28 Impact factor: 3.641
Authors: Huiying Chua; Shuo Feng; Joseph A Lewnard; Sheena G Sullivan; Christopher C Blyth; Marc Lipsitch; Benjamin J Cowling Journal: Epidemiology Date: 2020-01 Impact factor: 4.822
Authors: Mrinmoy Sanyal; Tyson H Holmes; Holden T Maecker; Randy A Albrecht; Cornelia L Dekker; Xiao-Song He; Harry B Greenberg Journal: J Infect Dis Date: 2019-04-19 Impact factor: 5.226
Authors: Huong Q McLean; Herve Caspard; Marie R Griffin; Manjusha Gaglani; Timothy R Peters; Katherine A Poehling; Christopher S Ambrose; Edward A Belongia Journal: JAMA Netw Open Date: 2018-10-05