Footnotes

• Handling editor Anna Maria Geretti

• Twitter @Bret_S_Palmer

• Contributors BP conceived and designed the work as well as drafted and revised it critically for important intellectual content. BP will be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

• Funding The VZV case–control study was funded by the Florey Clinic, Reading. The author has received no financial contribution for this work.

• Competing interests None declared.

• Provenance and peer review Not commissioned; internally peer reviewed.