Influence of Prior Influenza Vaccination on Current Influenza Vaccine Effectiveness in Children Aged 1 to 5 Years

Kazuhiro Matsumoto; Wakaba Fukushima; Saeko Morikawa; Masashi Fujioka; Tohru Matsushita; Megumi Kubota; Yoshina Yagi; Yoshio Takasaki; Shizuo Shindo; Yuji Yamashita; Takato Yokoyama; Yumi Kiyomatsu; Satoshi Hiroi; Keiko Nakata; Akiko Maeda; Kyoko Kondo; Kazuya Ito; Tetsuo Kase; Satoko Ohfuji; Yoshio Hirota

doi:10.3390/vaccines9121447

Influence of Prior Influenza Vaccination on Current Influenza Vaccine Effectiveness in Children Aged 1 to 5 Years

Vaccines (Basel). 2021 Dec 7;9(12):1447. doi: 10.3390/vaccines9121447.

Authors

Kazuhiro Matsumoto¹, Wakaba Fukushima^{1

2}, Saeko Morikawa³, Masashi Fujioka⁴, Tohru Matsushita⁵, Megumi Kubota⁶, Yoshina Yagi⁷, Yoshio Takasaki⁸, Shizuo Shindo⁹, Yuji Yamashita¹⁰, Takato Yokoyama¹¹, Yumi Kiyomatsu¹², Satoshi Hiroi³, Keiko Nakata³, Akiko Maeda¹, Kyoko Kondo¹³, Kazuya Ito^{1

2

14

15}, Tetsuo Kase^{1

2}, Satoko Ohfuji^{1

2}, Yoshio Hirota¹⁵

Affiliations

¹ Department of Public Health, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
² Research Center for Infectious Disease Sciences, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
³ Department of Virology, Osaka Institute of Public Health, Osaka 537-0025, Japan.
⁴ Fujioka Pediatric Clinic, Tondabayashi 584-0074, Japan.
⁵ Matsushita Kids' Clinic, Kadoma 571-0030, Japan.
⁶ Kubota Children's Clinic, Osaka 544-0033, Japan.
⁷ Yagi Pediatric Clinic, Yao 581-0871, Japan.
⁸ Takasaki Pediatric Clinic, Fukuoka 819-0052, Japan.
⁹ Shindo Children's Clinic, Fukuoka 814-0121, Japan.
¹⁰ Yamashita Pediatric Clinic, Itoshima 819-1112, Japan.
¹¹ Yokoyama Children's Clinic, Kasuga 816-0801, Japan.
¹² Kiyomatsu Pediatric Clinic, Fukuoka 814-0021, Japan.
¹³ Management Bureau, Osaka City University Hospital, Osaka 545-8586, Japan.
¹⁴ Healthcare Management, College of Healthcare Management, Miyama 835-0018, Japan.
¹⁵ Clinical Epidemiology Research Center, SOUSEIKAI, Fukuoka 813-0017, Japan.

Abstract

Background: Although annual influenza vaccination is an important strategy used to prevent influenza-related morbidity and mortality, some studies have reported the negative influence of prior vaccination on vaccine effectiveness (VE) for current seasons. Currently, the influence of prior vaccination is not conclusive, especially in children.

Methods: We evaluated the association between current-season VE and prior season vaccination using a test-negative design in children aged 1-5 years presenting at nine outpatient clinics in Japan during the 2016/17 and 2017/18 influenza seasons. Children with influenza-like illness were enrolled prospectively and tested for influenza using real-time RT-PCR. Their recent vaccination history was categorized into six groups according to current vaccination doses (0/1/2) and prior vaccination status (unvaccinated = 0 doses/vaccinated = 1 dose or 2 doses): (1) 0 doses in the current season and unvaccinated in prior seasons (reference group); (2) 0 doses in the current season and vaccinated in a prior season; (3) 1 dose in the current season and unvaccinated in a prior season; (4) 1 dose in the current season and vaccinated in a prior season; (5) 2 doses in the current season and unvaccinated in a prior season, and (6) 2 doses in the current season and vaccinated in a prior season.

Results: A total of 799 cases and 1196 controls were analyzed. The median age of the subjects was 3 years, and the proportion of males was 54%. Overall, the vaccination rates (any vaccination in the current season) in the cases and controls were 36% and 53%, respectively. The VEs of the groups were: (2) 29% (95% confidence interval: -25% to 59%); (3) 53% (6% to 76%); (4) 70% (45% to 83%); (5) 56% (32% to 72%), and (6) 61% (42% to 73%). The one- and two-dose VEs of the current season were significant regardless of prior vaccination status. The results did not differ when stratified by influenza subtype/lineage.

Conclusion: Prior vaccination did not attenuate the current-season VE in children aged 1 to 5 years, supporting the annual vaccination strategy.

Keywords: influenza; repeated vaccination; test-negative design.