Mills 2010.

Methods	Study design: RCT, double‐blind, cross‐over Duration: 28 days after each injection
Participants	Inclusion criteria Setting: outpatient Country: USA, 9 centres Number: 101 participants; treatment (N = 51), control (N = 50) Participants' health status: healthy participants with physician‐documented history of herpes zoster ≥ 5 years prior to screening Age: mean ˜ 67.9 years Sex: ˜ 59% female Other relevant information: aged ≥ 50 years. Only data for participants aged ≥ 60 years were used in this review. ˜ 88.1% Caucasian (understood to be white) Exclusion criteria "Subjects were excluded if they had an episode of HZ <5 years before study entry; ≥ 2 prior episodes of HZ; previous vaccination with any VZV‐containing vaccine; immune deficiency associated with illness or medical treatments; received blood products within 5 months prior to the first study dose through 8 weeks after enrolment; had hypersensitivity or anaphylactic reactions to gelatin or neomycin; currently were using any form of non‐topical antiviral therapy; received any live vaccine 4 weeks prior to the first study dose or during the study period or received any inactivated vaccine 7 days prior to the first study dose or during the study period; or had a history of alcohol or drug abuse."
Interventions	SC lyophilised (frozen) live zoster vaccine and 4 weeks later SC placebo SC placebo and SC lyophilised (frozen) live zoster vaccine 4 weeks later Treatment group SC lyophilised (frozen) live zoster vaccine (51 participants); N = 80 Control group SC placebo; N = 81
Outcomes	In participants aged ≥ 60 years Adverse events: 1 or more adverse event, injection site adverse events, systemic and vaccine‐related systemic adverse events Dropouts
Purpose of the study	"To determine the safety profile and immunogenicity of zoster vaccine in individuals who experienced a prior episode of herpes zoster"
Funding sources	Merck & Co Inc
Conflicts of interest	Janie Parrino, Xiaoming Li, Kathleen E Coll, Jon E Stek, Katia Schlienger, Ivan SF Chand, Jeffrey L Silber are employees of Merck Research Laboratories, PO Box 1000, North Wales, PA 19454, USA. Other authors have been investigators for the sponsor. Keith S Reisinger has also received speaker fees and consultancy payments from the sponsor. Employees may hold stock or stock options, or both, in the company.
Notes	"The same subject may appear in different categories, but was counted only once in each category" Data were analysed with pooled data from cross‐over arms because separate data were not available. We contacted the author and received a reply. There was no separate analysis for the first arm prior to cross‐over.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Double‐blind, but it was not explained how this was achieved
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not described
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described
Incomplete outcome data (attrition bias) All outcomes	High risk	No data from the first arm of this cross‐over study were reported.
Selective reporting (reporting bias)	Low risk	All of the adverse events listed in the methods section were described in the results.
Other bias	High risk	Cross‐over study