The expected number of background disease events during mass immunization in China.

Youxin Wang,Xinwei Yu,Manshu Song,Feifei Zhao,Lijuan Wu,Alyce Russell,Wei Wang

doi:10.1371/journal.pone.0071818

Abstract

It is critical to distinguish events that are temporarily associated with, but not caused by, vaccination from those caused by vaccination during mass immunization. We performed a literature search in China National Knowledge Infrastructure and Pubmed databases. The number of coincident events was calculated based on its incidence rate and periods after receipt of a dose of hypothesized vaccine. We included background incidences of Guillain-Barré syndrome, anaphylaxis, seizure, sudden adult death syndrome, sudden cardiac death, spontaneous abortion, and preterm labour or delivery. In a cohort of 10 million individuals, 7.71 cases of Guillain-Barré syndrome would be expected to occur within six weeks of vaccination as coincident background cases. Even for rare events, a large number of events can be expected in a short period because of the large population targeted for immunization. These findings may encourage health authorities to screen the safety of vaccines against unpredictable pathogens.

Highlights

In 2009, a novel influenza A H1N1 virus emerged from Mexico and spread quickly worldwide
We identified the background rates of selected medical events in China and estimated the safety of the pandemic H1N1 influenza vaccines made in China
The incidence of Guillain-Barre Syndrome was higher in men than in women, varying from 0.74 to 1.02 per 100,000 person-years in males and 0.57 to 0.79 per 100,000 person-years in females of all ages [9,10]

Summary

Introduction

In 2009, a novel influenza A H1N1 virus emerged from Mexico and spread quickly worldwide. Up to February 28th 2010, 82.12 million individuals had been vaccinated with pandemic H1N1 influenza vaccines [1]. Black and colleagues raised the importance of background rates of disease in monitoring H1N1 vaccine safety during mass immunization with pandemic H1N1 influenza vaccines, and estimated the expected background rates of occurrence of several health conditions [2]. Deeks and colleagues estimated background rates of Guillain-Barre Syndrome in Ontario while responding to safety concerns during the pandemic H1N1/09 immunization campaign [3]. Our findings supply the expected number of background disease events during mass immunization against emerging infectious disease, and this is the first attempt in China to estimate the safety of mass

Methods

Results

Conclusion