Accepted for/Published in: JMIR Public Health and Surveillance
Date Submitted: Sep 23, 2023
Date Accepted: Feb 5, 2024
:Investigating Non-specific Effects of the Japanese Encephalitis Vaccine on Lower Respiratory Tract Infections in Children Aged 25-35 Months.
ABSTRACT
Background:
Live attenuated vaccines may be used to prevent non-targeted diseases such as lower respiratory tract infections (LRTI) due to their non-specific effects (NSE).
Objective:
We aimed to analyze the NSE of the Japanese encephalitis vaccine on pediatric LRTI during 25-35 months of age.
Methods:
A retrospective cohort study was conducted by using a population-based electronic health record database in Zhejiang, China. Enrolled participants were children born during January 1, 2017, to December 31, 2017, and who were inoculated with the live attenuated Japanese encephalitis vaccine (JE-L) or inactivated Japanese encephalitis vaccine (JE-I) as the most recent vaccine at 24 months of age. The study was carried out between January 1, 2019, to December 31, 2019. All in- and out-hospital visits for LRTI among children aged 25-35 months were recorded. Andersen-Gill model was used to assess the NSE of JE-L on children against LRTI and compared with those of JE-I as their most recent vaccine.
Results:
A total of 810 children born in 2017 were enrolled, of whom 585 received JE-L (JE-L cohort) and 225 received JE-I (JE-I cohort) as their last vaccine. The JE-L cohort showed reduced risk of LRTI (aHR=0.537, 95%CI: 0.416-0.693), including pneumonia (aHR=0.501, 95%CI: 0.393-0.638) and acute bronchitis (aHR=0.525, 95%CI: 0.396-0.698) during 25-35 months of age. The NSE provided by JE-L were especially pronounced in females (aHR=0.305, 95%CI: 0.198-0.469), those without chronic diseases (aHR=0.553, 95%CI: 0.420-0.729), without siblings (aHR=0.361, 95%CI: 0.255-0.511), having more than 30 in- and out-hospital visits prior to 24 months of age (aHR=0.163, 95%CI: 0.091-0.290), or having 5-10 in- and out-hospital visits prior to 24 months due to infectious diseases (aHR=0.058, 95%CI: 0.017-0.202).
Conclusions:
Receiving JE-L as the most recent vaccine was associated with lower risk of in- and out-hospital visits for LRTI among children aged 25-35 months compared with JE-I. The nature of NSE released by JE-L should be considered for policy makers and physicians when recommending JE vaccine to those in high risk of Japanese encephalitis virus.
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