Seropositivity of Varicella zoster virus in vaccinated Korean children and MAV vaccine group

Park

Human Vaccines & Immunotherapeutics

et al. 2019

Self Cite

Background: In South Korea, the one-dose varicella vaccine was included in the National Immunization Program for children aged 12-15 months in 2005, and the vaccine coverage reached >95%. The impact of varicella vaccination on varicella and herpes zoster (HZ) was investigated, accounting for demographic changes over time. Methods: We calculated the crude and age-sex standardized incidence rates (IRs) and age-specific IRs of varicella and HZ from 2003 to 2015, using the National Health Information Database including approximately 50 million Koreans. The annual incidence rate ratios (IRRs) were calculated using a negative binomial regression analysis, adjusting for age and sex. Results: The crude varicella IR steadily declined by 67%, from 5.70/1000 to 1.87/1000 person years (IRR per year: 0.91; 95% CI 0.89-0.93), but the adjusted IRs showed a significant decline only during 2010-2015 (adjusted IRR per year: 0.90; 95% CI 0.88-0.93). The greatest decline was found in children ≤4 years of age, whereas the IR increased until 2011 and then declined afterward in children aged 5-9 years, who represented the highest incidence age group in 2013-2015. The crude HZ IR increased from 2.67/1000 to 9.80/1000 person years (IRR per year: 1.12; 95% CI 1.10-1.15), and the adjusted IR also followed the same trend. A similar increasing trend was observed before and after universal vaccination. Conclusions: One-dose varicella vaccination was moderately effective in preventing varicella, but this strategy was insufficient to interrupt varicella transmission in children. Furthermore, the HZ incidence dramatically increased over this decade. The current vaccination strategy against varicella-zoster disease should be reconsidered.

Section: Discussionmentioning

confidence: 99%

Trends in varicella and herpes zoster epidemiology before and after the implementation of universal one-dose varicella vaccination over one decade in South Korea, 2003–2015

Park

Human Vaccines & Immunotherapeutics

et al. 2019

Self Cite

“…Another retrospective cohort study involving students attending elementary school suggested that 99% of one-dose vaccination coverage was not sufficient to prevent varicella outbreaks [22]. A longitudinal seroprevalence study in Korea showed a progressive decrease of the seropositivity rates following vaccination: 65% at age 1 year, 59% at age 2 years, 53% at age 3 years and 49% at age 4 years [23]. One may also postulate that one dose of varicella vaccination may result in secondary vaccine failure, or waning of immunity over time.…”

Section: Discussionmentioning

confidence: 99%

Increasing varicella incidence rates among children in the Republic of Korea: an age–period–cohort analysis

et al. 2019

In the Republic of Korea, despite the introduction of one-dose universal varicella vaccination in 2005 and achieving a high coverage rate of 98.9% in 2012, the incidence rate has been increased sevenfold. This study aimed to investigate time trends of varicella incidence rate, assessing the age, period and birth cohort effects. We used national data on the annual number of reported cases from 2006 to 2017. A log-linear Poisson regression model was used to estimate age–period–cohort effects on varicella incidence rate. From 2006 to 2017, the incidence of varicella increased from 22.5 cases to more than 154.8 cases per 100 000. Peak incidence has shifted from 4 to 6 years old. The estimated period and cohort effects showed significant upward patterns, with a linear increasing trend by net drift. There has been an increase in the incidence among the Korean population regarding period and cohort despite the universal vaccination of varicella vaccine. Our data suggest the need for additional studies to address the current gap in herd immunity.

“…However, two clinical trials (2223) and a recent clinical case-control study (11) showed that the vaccine did not ameliorate disease severity and was poorly immunogenic. A recent immunogenicity study on MAV and Oka (Vari-L) vaccine showed that the MAV vaccine generated higher seropositivity rates and antibody titers than the Oka vaccine and provided immunity against VZV, despite waning of immunity observed (24). Not all Oka vaccine in this study, however, were effective against VZV, so it cannot directly be interpreted that MAV vaccine is effective.…”

Section: Discussionmentioning

confidence: 99%

Effectiveness of Varicella Vaccination Program in Preventing Laboratory-Confirmed Cases in Children in Seoul, Korea

et al. 2016

A universal one-dose varicella vaccination program was introduced in 2005 in Republic of Korea. However, the incidence of varicella in Korea has tripled over the last decade. We conducted a community based 1:1 matched case-control study to assess the effectiveness of one MAV strain-based vaccine and three Oka strain-based vaccines licensed for use in Korea. All cases were children in Seoul, Korea with varicella who were reported to the National Notifiable Disease Surveillance System in Seoul during 2013. The controls were age-matched children with mumps or scarlet fever but no history of varicella. We included 537 cases and 537 controls. The overall effectiveness of one dose of varicella vaccination was 13% (95% confidence interval [CI], −17.3–35.6). Of the four licensed varicella vaccines, only one was highly effective (88.9%; 95% CI, 52.1–97.4). The vaccine effectiveness for the other vaccines were 71.4% (95% CI, −37.5–94.1), −5% (95% CI, −61.9–31.9), and −100% (95% CI, −700–50.0). The overall effectiveness of vaccination was 75.8% (95% CI, 22.8–92.4) in the first year after vaccination and decreased thereafter; the effectiveness became −7.2% (95% CI, −130.9–59.2) in the fourth year after vaccination. Further studies are warranted to investigate reduced effectiveness of varicella vaccines in Korea.