Source:

Li
R
,
Liu
L
,
Mo
Z
, et al
.
An inactivated enterovirus 71 vaccine in healthy children
.
N Engl J Med
.
2014
;
370
(
9
):
829
837
; doi:
https://doi.org/10.1056/NEJMoa1303224

Investigators from multiple institutions in China conducted a randomized controlled trial to evaluate the safety and efficacy of an inactivated enterovirus 71 (EV71) vaccine. Healthy children 6 to 71 months of age were randomly assigned to receive EV71 vaccine or placebo. Two doses of vaccine or placebo were administered intramuscularly, with a 4-week interval between doses. The primary efficacy end point was protection against hand, foot, and mouth disease (HFMD) caused by EV71. Cases of EV71-associated HFMD were defined as clinically diagnosed HFMD in which EV71 was subsequently detected by reverse transcription polymerase chain reaction from a throat swab or stool specimen. Identification of coxsackievirus A16 and other enteroviruses was also performed on these specimens. Efficacy was assessed from 2 weeks after completion of the 2-dose schedule until 1 year after receipt of the first dose. The proportion of participants hospitalized due to clinically diagnosed HFMD – and their clinical course – was also compared between the vaccine and placebo groups. Data on adverse events during the 7 days after each injection were also collected.

A total of 12,000 children (6,000 in each group) were enrolled and received the first dose. A total of 5,486 children in the vaccine group and 5,502 children in the placebo group received the second dose (8.4% withdrawal rate). There were 594 cases of clinically diagnosed HFMD (202 in the vaccine group and 392 in the placebo group). Among these, 155 were identified as EV71-associated HFMD with 4 cases occurring in the vaccine group and 151 in the placebo group, representing a vaccine efficacy of 97.4% (95% CI, 92.9–99.0). There were 102 clinically diagnosed cases that were caused by coxsackievirus A16 and 234 caused by other enteroviruses; the vaccine showed no efficacy against HFMD caused by coxsackievirus A16 or other enteroviruses. There were 41 participants in the vaccine group who were hospitalized for clinically diagnosed HFMD, compared to 88 in the placebo group (P < .001); 1 child in the placebo group died from EV71-associated HFMD.

Within 7 days after each injection, systemic adverse events were more common in the vaccine group than the placebo group (48.6% vs 42.9%, P < .001). The most common reactions were fever, diarrhea, nausea, and vomiting. Local adverse events, including pain, redness, swelling, and itching at the injection site, were higher in the vaccine group than in the placebo group (5.9% vs 2.3%, P < .001).

The investigators conclude that the inactivated EV71 vaccine was safe and provided protection against EV71-associated HFMD.

Dr. Brady has disclosed no financial relationship relevant to this commentary. This commentary does contain a discussion of an unapproved/investigative use of a commercial product/device.

Most enterovirus infections are either asymptomatic or manifest as mild upper respiratory infections, herpangina, or HFMD. However, the neurologic...

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