Epidemiological Characteristics of Varicella Outbreaks — China, 2006–2022

Abstract

Introduction Varicella outbreaks significantly disrupt schools and other child-centered institutions. This study aimed to identify patterns and epidemiological features of varicella outbreaks in China from 2006 to 2022. Methods Data were extracted from outbreak reports submitted to the Public Health Emergency Reporting Management Information System within the specified timeframe. Analytical methods included Spearman correlation tests and the Mann-Kendall trend tests, conducted using R software to analyze and summarize reported data. Additionally, statistical analyses of trends and epidemiological characteristics were performed using SPSS software. Results Between 2006 and 2022, a total of 11,990 varicella outbreaks were reported in China, resulting in 354,082 cases. The attack rates showed a decreasing trend over the years (Z=−4.49, P <0.05). These outbreaks occurred in two peaks annually. The eastern region accounted for the highest number of outbreaks (31.53%), followed by the southwestern (24.22%) and southern (17.93%) regions. Varicella outbreaks were most common in elementary schools. Most of the outbreaks (60.43%) were classified as Grade IV (general) severity, with 86.41% of the outbreaks having 10–49 cases. The median and inter-quartile ranges (IQR) of the duration of outbreaks, response time, and case counts were 21 (10, 39) days, 4 (0, 12) days, and 23 (16, 35) cases, respectively. These variables showed a positive correlation ( P <0.001). Conclusions Varicella outbreaks exhibited fluctuating trends, initially decreasing until 2012, followed by an increase, reaching the highest peak in 2018–2019. Continual monitoring of varicella epidemiology is necessary to assess the burden of the disease and formulate evidence-based strategies and policies for its prevention and control.

Trends and Age-Period-Cohort Effect on Incidence of Varicella Under Age 35 — China, 2005–2021

“…Standardized diagnostic procedures have played a crucial role in achieving this (8)(9). Additionally, certain regions have heightened their management of varicella cases to ensure accurate reporting and a more representative incidence level (2,4). Furthermore, the impact of global warming on the risk of varicella cannot be overlooked.…”

“…The incidence of varicella is primarily observed in children, although recent studies have shown an increasing incidence rate and proportion among the elderly population (1)(2). Previous research has mostly focused on describing the epidemiological characteristics of varicella in specific provincial-level administrative division (PLAD) or cities in China (3)(4). However, there is a lack of studies investigating long-term patterns of varicella incidence by gender, age, period, and cohort.…”