Varicella Outbreak Surveillance in Schools in Sentinel Jurisdictions, 2012–2015

Abstract

The majority of cases associated with outbreaks occurred in undervaccinated children (unvaccinated and 1-dose vaccine recipients). Outbreaks with a greater proportion of 2-dose vaccine recipients were smaller. Varicella outbreak surveillance is feasible, and continued monitoring of outbreaks remains important for describing the epidemiology of varicella during the 2-dose varicella vaccination program.

Varicella outbreak in a highly-vaccinated school population in Beijing, China during the voluntary two-dose era

“…The differential exposure to VZV in these two outbreaks, which was indicated in the low attack rates and substantial variation between classes, might lead to biased estimates on varicella VE, as equal exposure to disease is important but may not be achievable for VE assessment in outbreak investigations [17]. The findings of reduced outbreak size and duration in the current outbreak compared with outbreaks in similar school populations with high 1-dose coverage but almost no 2-dose vaccinees or low 2 dose coverage [5,11] were consistent with the changes in varicella outbreak characteristics before and after introduction of the 2-dose universal recommendation in the US [18], and the trend for smaller size of outbreaks with a greater proportion of 2-dose vaccine recipients [19]. Additionally, in the US a substantial decline of varicella disease burden had been observed after 2-dose varicella vaccination program introduction [20].…”

Varicella-zoster virus post-exposure management and prophylaxis: A review

“…Maintaining high varicella vaccination rates is essential for preventing disease outbreaks and reducing the risk of VZV exposure (Lopez et al, 2019). As of 2017, rates of ≥1 dose of varicella vaccination among children 19–35 months of age in the US ranged from 76% to 98% (Fig.…”

“…In addition to geographic disparities, vaccination rates differ amongst racial/ethnic groups and between foreign-born and US-born populations (Hill et al, 2018, Healy et al, 2018). Estimated 2-dose vaccination coverage rates needed to achieve population-level protection and prevent outbreaks range from 75% to 88% (Lopez et al, 2019). Between 2012 and 2015, 29 varicella outbreaks were reported in 10 sentinel jurisdictions with active varicella surveillance (Lopez et al, 2019).…”

“…Estimated 2-dose vaccination coverage rates needed to achieve population-level protection and prevent outbreaks range from 75% to 88% (Lopez et al, 2019). Between 2012 and 2015, 29 varicella outbreaks were reported in 10 sentinel jurisdictions with active varicella surveillance (Lopez et al, 2019). Undervaccination (i.e., no vaccination or 1-dose recipients) is associated with larger outbreaks (Lopez et al, 2019).…”

“…Between 2012 and 2015, 29 varicella outbreaks were reported in 10 sentinel jurisdictions with active varicella surveillance (Lopez et al, 2019). Undervaccination (i.e., no vaccination or 1-dose recipients) is associated with larger outbreaks (Lopez et al, 2019). Additionally, implementation of second-dose vaccination for outbreak control in 1-dose recipients reduced varicella incidence and severity (Nguyen et al, 2010).…”