Immunity and clinical efficacy of an inactivated enterovirus 71 vaccine in healthy Chinese children: a report of further observationsReport as inadecuate

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BMC Medicine

, 13:226

First Online: 17 September 2015Received: 30 March 2015Accepted: 12 August 2015DOI: 10.1186-s12916-015-0448-7

Cite this article as: Liu, L., Mo, Z., Liang, Z. et al. BMC Med 2015 13: 226. doi:10.1186-s12916-015-0448-7


BackgroundTo investigate the long-term effects on immunity of an inactivated enterovirus 71 EV71 vaccine and its protective efficacy.

MethodsA sub-cohort of 1,100 volunteers from Guangxi Province in China was eligible for enrolment and randomly administered either the EV71 vaccine or a placebo on days 0 and 28 in a phase III clinical trial and then observed for the following 2 years with approval by an independent ethics committee of Guangxi Zhuang Autonomous Region, China. Serum samples from the 350 participants who provided a full series of blood samples at all the sampling points within the 2-year period were collected. Vaccine-induced immune effects, including the neutralizing antibody titres and cross-protection against different genotypes of EV71, were examined. This study also evaluated the protective efficacy of this vaccine based upon clinical diagnosis.

ResultsThis sub-cohort showed a >60 % drop-out rate over 2 years. The seroconversion rates among the 161 immunized subjects remained >95 % at the end of study. The geometric mean titres of neutralizing antibodies anti-genotype C4 360 days after vaccination in 350 subjects were 81.0 subjects aged 6–11 months, 98.4 12–23 months, 95.0 24–35 months, and 81.8 36–71 months. These titres subsequently increased to 423.1, 659.0, 545.0, and 321.9, respectively, at 540 days post-immunization d.p.i., and similar levels were maintained at 720 d.p.i. Higher IFN-γ-IL-4-specific responses to the C4 genotype of EV71 and cross-neutralization reactivity against major EV71 genotype strains were observed in the vaccine group compared to those in the placebo group. Five EV71-infected subjects were observed in the placebo-treated control group and none in the vaccine-immunized group in per-protocol analysis.

ConclusionThese results are consistent with the induction of dynamic immune responses and protective efficacy of the vaccine against most circulating EV71 strains.

Trial registration, NCT01569581, Trial registration date: March 2012

KeywordsCross-neutralization Enterovirus 71 Hand foot and mouth disease Inactivated vaccine Long-term effect AbbreviationsCA16Coxsackievirus A16

ELISPOTEnzyme-linked immunospot

EV71Enterovirus 71

GMTsGeometric mean titres

HFMDHand, foot, and mouth disease

IFN-γInterferon γ

IL-4Interleukin 4

PBMCsPeripheral blood mononuclear cells

Longding Liu Zhaojun Mo Zhenglun Liang Ying Zhang and Rongcheng Li contributed equally to this work.

Electronic supplementary materialThe online version of this article doi:10.1186-s12916-015-0448-7 contains supplementary material, which is available to authorized users.

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Author: Longding Liu - Zhaojun Mo - Zhenglun Liang - Ying Zhang - Rongcheng Li - Kien Chai Ong - Kum Thong Wong - Erxia Yang - Y


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