Footnotes

• Contributors All authors were involved in the production of this letter.

• Funding KAH was supported by the Charles Wolfson Charitable Trust and Specialised Laboratory Equipment (SLE). The research was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London.

• Disclaimer The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

• Competing interests None declared.

• Patient consent Not required.

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

• Data sharing statement We agree to sharing data on request.