Immunogenicity of single-dose Vero cell-derived Japanese encephalitis vaccine in Japanese adults.
In Japan, intensive immunization against Japanese encephalitis (JE) was performed from 1967 to 1976, and regular JE immunization was performed thereafter. However, for Japanese adults facing JE risk, dates of vaccination with new inactivated Vero cell-derived JE vaccine are unavailable. This study investigated how a single dose of Vero cell-derived JE vaccine affects Japanese adults. Neutralizing antibodies were measured pre- and post-JE vaccination in 79 participants (age 40.7 ± 9.4 years), enrolled between October 2009 and March 2011, whose JE-vaccination data were gathered from vaccination records and history taking. Before vaccination, the participants' seroprotection rate (SPR) was 51.9%, whereas SPR after vaccination was 93.7%. The seroconversion rate (SCR), which measures seronegative cases that turn seropositive after vaccination, was 86.8%. The geometric mean titer (GMT) was 14.7 before vaccination and 70.1 after vaccination. Age was a significant difference between seroprotected (42.8 years) and non-seroprotected (38.7 years) groups before vaccination. Then the difference of age, SCR, pre-vaccination GMT, post-vaccination GMT and sex ratio were also significant in participants aged 25-39 years and ≥40 years, who represent generations born when Japan's JE-vaccination policy changed. SCR was 100% in participants aged 25-39 years with a vaccination recorded 55.6% in participants aged 25-39 without a vaccination record, and 96.0% in participants aged ≥40 years. Thus, more participants aged 25-39 years were seroprotected before vaccination, but SCR was higher in those aged ≥40 years. Most Japanese adults can be protected after one-dose vaccination, but this may be insufficient for people aged 25-39 years without recorded JE vaccination.
Disease Control and Prevention Center, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. Electronic address: nozomitake@gmail.com.
Nozomi
N
Takeshita
Department of Virology 1, National Institute of Infectious Diseases, Tokyo, Japan. Electronic address: ck@nih.go.jp.
Chang-Kweng
CK
Lim
Department of Infection Control and Prevention, Tokyo Medical University, Japan. Electronic address: mizunomd@hotmail.com.
Yasutaka
Y
Mizuno
Department of Clinical Research and Informatics, International Clinical Research Center, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. Electronic address: tshimbo@hosp.ncgm.go.jp.
Takuro
T
Shimbo
Department of Virology 1, National Institute of Infectious Diseases, Tokyo, Japan. Electronic address: ak@nih.go.jp.
Akira
A
Kotaki
Disease Control and Prevention Center, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. Electronic address: infinite_u@hotmail.com.
Mugen
M
Ujiie
Disease Control and Prevention Center, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. Electronic address: kayokohayakawa@gmail.com.
Kayoko
K
Hayakawa
Disease Control and Prevention Center, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. Electronic address: ykato@hosp.ncgm.go.jp.
Yasuyuki
Y
Kato
Disease Control and Prevention Center, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan. Electronic address: skanagaw@hosp.ncgm.go.jp.
Shuzo
S
Kanagawa
Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan. Electronic address: kaku-m77@med.tohoku.ac.jp.
Mitsuo
M
Kaku
Department of Virology 1, National Institute of Infectious Diseases, Tokyo, Japan. Electronic address: takasaki@nih.go.jp.
Tomohiko
T
Takasaki
D000328:Adult; D000818:Animals; D002522:Chlorocebus aethiops; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D022321:Japanese Encephalitis Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D014709:Vero Cells
D022321:Japanese Encephalitis Vaccines
Japanese; Japanese encephalitis; Travel vaccine; Vero cells