Post-Marketing Surveillance of Adverse Events Following Vaccination with the Live-Attenuated Japanese Encephalitis Chimeric Virus Vaccine (Imojev®) in South Korea, 2015–2019

Abstract

Introduction: The live attenuated Japanese encephalitis chimeric virus vaccine (JE-CV; Imojev Ò) has been approved in South Korea for use in subjects aged C 12 months since 2015. As part of the license agreement, a post-marketing surveillance study was undertaken to actively monitor the safety profile of JE-CV in the Korean population. Methods: An observational, active safety surveillance study was conducted from 3 April 2015 through to 2 April 2019 at 12 centers in South Korea. Subjects aged C 12 months who received a single dose of JE-CV (primary or booster) during a routine healthcare visit were recruited and followed up for solicited reactions (7 and 14 days for injection site and systemic reactions, respectively), non-serious unsolicited adverse events and serious adverse events within 42 days after vaccination. Results: Overall, 810 subjects who received JE-CV were included in our analysis, the majority received the vaccine as a primary vaccination (94.9%; 769/810). There were 179 solicited reactions reported by 111 subjects; the majority of solicited reactions occurred within 0-3 days (80.4%; 144/179), were of 1-3 days' duration (79.3%; 142/179) and of grade 1 intensity (70.9%; 127/179). There were three grade 3 adverse reactions (irritability, pyrexia and malaise); all resolved within a few days. The incidence of solicited reactions were highest in those aged 12 to \ 24 months (34.7% [52/150] subjects; 107 events) and 2 to \ 10 years (17.8% [8/45] subjects; 14 events). All unsolicited adverse events (serious and non-serious) were unrelated to vaccination. There were no discontinuations due to adverse reactions/events. Conclusion: JE-CV has a good safety profile under practice conditions in South Korea. No new safety issues were identified.

Safety profile comparison of chimeric live attenuated and Vero cell-derived inactivated Japanese encephalitis vaccines through an active surveillance system in Australia

“… 23 , 24 When comparing Imojev and JEspect, the former presented ~30% higher odds of AEFI, though the difference was not statistically significant and unlikely to be of any clinical significance. Our study also support findings from previous JE vaccine clinical trials 15 , 16 as well as smaller post-marketing studies with passive 25 and active 26 surveillance systems that AEFIs are age-dependent and more frequent among children aged <5 years.…”

“… 27 Previous surveillance studies have found that individuals who received concomitant vaccines were more likely to report AEFIs compared to those who only received JE vaccine. 25 , 26 , 28 The evidence on AEFIs after receiving specific combinations of vaccines is sparse. Capeding et al found that infants (aged 9–10 months) who received concomitant live attenuated SA 14–14-2 JE and MMR vaccines compared to JE vaccine alone were twice as likely to develop fever, rash, diarrhea, and irritability.…”

Safety of Japanese encephalitis vaccines

“…59,60 Moreover, clinical studies and post-marketing surveillance all showed favorable safety profile of JE-CV (Table 1). [61][62][63][64][65][66][67][68] The most common adverse effects were injection site reaction with incidence of 6.3% to 37.8% and fever (3.6%-39.0%). Solicited adverse reactions following vaccination were most frequently reported in children younger than 24 months of age.…”

“…Solicited adverse reactions following vaccination were most frequently reported in children younger than 24 months of age. 63 , 68 Few serious adverse reactions had been reported, but further investigations showed unrelatedness to JE–CV vaccination.…”