Effects of Varicella Vaccine Time of First Dose and Coverage of Second Dose - Beijing and Ningbo, China, 2012-2018

An Autoregressive Integrated Moving Average Model for Predicting Varicella Outbreaks - China, 2019

Introduction

Varicella, a prevalent respiratory infection among children, has become an escalating public health issue in China. The potential to considerably mitigate and control these outbreaks lies in surveillance-based early warning systems. This research employed an autoregressive integrated moving average (ARIMA) model with the objective of predicting future varicella outbreaks in the country.

Methods

An ARIMA model was developed and fine-tuned using historical data on the monthly instances of varicella outbreaks reported in China from 2005 to 2018. To determine statistically significant models, parameter and Ljung-Box tests were employed. The coefficients of determination (R2) and the normalized Bayesian Information Criterion (BIC) were compared to selecting an optimal model. This chosen model was subsequently utilized to forecast varicella outbreak cases for the year 2019.

Results

Four models passed parameter (all P<0.05) and Ljung-Box tests (all P>0.05). ARIMA (1, 1, 1)×(0, 1, 1)12 was determined to be the optimal model based on its coefficient of determination R2 (0.271) and standardized BIC (14.970). Fitted values made by the ARIMA (1, 1, 1)×(0, 1, 1)12 model closely followed the values observed in 2019, the average relative error between the actual value and the predicted value is 15.2%.

Conclusion

The ARIMA model can be employed to predict impending trends in varicella outbreaks. This serves to offer a scientific benchmark for strategies concerning varicella prevention and control.

Effect of Earlier Vaccination and a Two-Dose Varicella Vaccine Schedule on Varicella Incidence - Beijing Municipality, 2007-2018

WHAT IS ALREADY KNOWN ABOUT THIS TOPIC?

The World Health Organization (WHO) varicella vaccines position paper states that countries where varicella is an important public health burden could consider introducing varicella vaccine (VarV) in the routine childhood immunization program (1). VarV has been available for many years in China but is not included in most routine immunization programs in China. As a result, substantial heterogeneity in vaccination coverage exists across regions.

WHAT IS ADDED BY THIS REPORT?

In Beijing, adding a second dose of VarV for children and increasing coverage reduced the incidence of varicella. Lowering the age of the first dose of VarV to 12 months could further reduce varicella, especially among toddlers.

WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE?

Governments should use economic analysis to consider inclusion of VarV into the routine children immunization program as a free vaccine and adopting a 2-dose schedule that starts at 12 months of age.