Shigeru Suga1, Naruhiko Ishiwada2, Yuko Sasaki3, Hideki Akeda4, Junichiro Nishi5, Kenji Okada6, Mikiya Fujieda7, Megumi Oda8, Kazutoyo Asada1, Takashi Nakano9, Akihiko Saitoh10, Mitsuaki Hosoya11, Takehiro Togashi12, Mayumi Matsuoka3, Kouji Kimura3, Keigo Shibayama3. 1. Infectious Disease Center and Department of Clinical Research, National Hospital Organization Mie Hospital, Mie, Japan. 2. Department of Infectious Diseases, Medical Mycology Research Center, Chiba University, Chiba, Japan. Electronic address: ishiwada@faculty.chiba-u.jp. 3. Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan. 4. Okinawa Prefectural Nanbu Medical Center & Children's Medical Center, Okinawa, Japan. 5. Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan. 6. Fukuoka Nursing College, Fukuoka, Japan. 7. Department of Pediatrics, Kochi Medical School, Kochi University, Kochi, Japan. 8. Okayama University Graduate School of Health Sciences, Okayama, Japan. 9. Department of Pediatrics, Kawasaki Medical School, Okayama, Japan. 10. Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. 11. Department of Pediatrics, Fukushima Medical University School of Medicine, Fukushima, Japan. 12. Hokkaido Anti-Tuberculosis Association, Hokkaido, Japan.
Abstract
BACKGROUND: Haemophilus influenzae type b (Hib) vaccine was introduced as a voluntary vaccine in December 2008 and was included in the national routine immunization program in April 2013 in Japan. Currently, no nationwide data are available to evaluate the effectiveness of Hib vaccine in Japan. METHODS: To evaluate the effectiveness of Hib vaccine in Japan, nationwide active population-based surveillance of culture-proven invasive infections caused by H. influenzae in children was performed in 2008-2017 in 10 prefectures in Japan (covering approximately 23% of the total Japanese population). Clinical data were recorded on a standardized case report form. Capsular type and antimicrobial susceptibility of the H. influenzae isolates were examined. The incidence rate ratio (IRR) and its confidence interval (CI) were calculated to compare data from 5 years before and that from after the introduction of the national routine Hib vaccine immunization program. RESULTS: During the 10-year study period, 566 invasive H. influenzae disease cases including 336 meningitis cases were identified. The average number of invasive H. influenzae disease cases among children <5 years of age during 2013-2017 decreased by 93% (IRR: 0.07, 95%CI 0.05-0.10, p < 0.001) compared with those occurring during 2008-2012. Hib strains have not been isolated from invasive H. influenzae disease cases since 2014; however, non-typeable H. influenzae and H. influenzae type f isolates have been noted as causes of invasive H. influenzae diseases among children <5 years in the post-Hib vaccine era. CONCLUSIONS: After the governmental subsidization of the Hib vaccine, invasive Hib disease cases decreased dramatically in the study population, as per our surveillance. Continuous surveillance is necessary to monitor the effectiveness of Hib vaccine and for detecting any emerging invasive capsular types.
BACKGROUND:Haemophilus influenzae type b (Hib) vaccine was introduced as a voluntary vaccine in December 2008 and was included in the national routine immunization program in April 2013 in Japan. Currently, no nationwide data are available to evaluate the effectiveness of Hib vaccine in Japan. METHODS: To evaluate the effectiveness of Hib vaccine in Japan, nationwide active population-based surveillance of culture-proven invasive infections caused by H. influenzae in children was performed in 2008-2017 in 10 prefectures in Japan (covering approximately 23% of the total Japanese population). Clinical data were recorded on a standardized case report form. Capsular type and antimicrobial susceptibility of the H. influenzae isolates were examined. The incidence rate ratio (IRR) and its confidence interval (CI) were calculated to compare data from 5 years before and that from after the introduction of the national routine Hib vaccine immunization program. RESULTS: During the 10-year study period, 566 invasive H. influenzae disease cases including 336 meningitis cases were identified. The average number of invasive H. influenzae disease cases among children <5 years of age during 2013-2017 decreased by 93% (IRR: 0.07, 95%CI 0.05-0.10, p < 0.001) compared with those occurring during 2008-2012. Hib strains have not been isolated from invasive H. influenzae disease cases since 2014; however, non-typeable H. influenzae and H. influenzae type f isolates have been noted as causes of invasive H. influenzae diseases among children <5 years in the post-Hib vaccine era. CONCLUSIONS: After the governmental subsidization of the Hib vaccine, invasive Hib disease cases decreased dramatically in the study population, as per our surveillance. Continuous surveillance is necessary to monitor the effectiveness of Hib vaccine and for detecting any emerging invasive capsular types.
Authors: N Takeuchi; S Naito; M Ohkusu; K Abe; K Shizuno; Y Takahashi; Y Omata; T Nakazawa; K Takeshita; H Hishiki; T Hoshino; Y Sato; N Ishiwada Journal: Epidemiol Infect Date: 2020-04-17 Impact factor: 2.451