Epidemiological characteristics of breakthrough varicella infection during varicella outbreaks in Shanghai, 2008–2014. Issue 10 (27th April 2017)

• Record Type: Journal Article
• Authors: ZHU, Y. F.; LI, Y. F.; DU, Y.; ZENG, M.
• Is Part Of: Epidemiology and infection. Volume 145:Issue 10(2017)
• Page Start: 2129
• Page End: 2136
• Publication Date: 2017-04-27
• Subjects: Breakthrough infection, -- outbreak, -- vaccination, -- varicella; Communicable diseases -- Periodicals; Epidemiology -- Periodicals; 614.4
• DOI: 10.1017/S0950268817000772
• Languages: English
• ISSNs: 0950-2688

Abstract

SUMMARY: The outbreaks of varicella occurring in kindergartens and schools are increasingly notified in Shanghai despite the implementation of one-dose varicella vaccination. We analyzed surveillance data on the notified outbreaks of varicella in Minhang District of Shanghai during 2008–2014. A total of 13 511 varicella cases and 154 outbreaks involving 1558 (11·5%) cases were reported. Annual attack rates of outbreak-associated varicella in outbreak classes were 5·5%–12%. The mean age of the outbreak-associated cases was 8·6 ± 3·1 years. Among 1558 outbreak cases, 660 (42·4%) received one-dose varicella vaccine previously. The proportions of breakthrough varicella infection during outbreaks ranged from 21·5% in 2008 to 86·1% in 2014. Annual breakthrough infection rates in outbreak classes ranged from 5·4% to 7·4%. Breakthrough cases as index cases results in 9·7% of outbreaks, and the average duration of outbreaks was significantly longer in vaccinated cases as index cases than in unvaccinated cases as index cases (11·3 ± 5·8 days vs . 8·6 ± 6·1 days, P < 0·05). The mean time of breakthrough infection since vaccination was 6·2 ± 2·3 years (range 0·6–13·4 years). One-dose varicella vaccination cannot prevent the varicella outbreaks in kindergartens and schools. A second dose of varicella vaccine should be recommended for children.