Footnotes

• Competing interests AF undertakes clinical research, advisory work and speaking engagements for all the major vaccine manufacturers including GSK and SP-MSD who market varicella vaccines in Europe. All income generated from these activities is paid to his employers at the University of Bristol and University Hospitals Bristol NHS Foundation Trust. He also undertakes unpaid advisory work concerning vaccines for the UK government and the WHO.

• Provenance and peer review Commissioned; externally peer reviewed.