The winter 2018/19 influenza season in Hong Kong has been predominated by influenza A(H1N1)pdm09 as at January 2019. We enrolled 2,016 children in three public hospitals in Hong Kong between 2 September 2018 and 11 January 2019. Using the test-negative approach, we estimated high early season effectiveness of inactivated influenza vaccine against influenza A or B of 90% (95% confidence interval (CI): 80-95%) and 92% (95% CI: 82-96%) against influenza A(H1N1)pdm09.
Chiu SS, Kwan MY, Feng S, Chan EL, Chua H, Wong JS, Peiris JM, Cowling BJ. (2019). Early season estimate of influenza vaccination effectiveness against influenza hospitalisation in children, Hong Kong, winter influenza season 2018/19. Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin, 24(5)