Footnotes

• Twitter @ChikazawaKenro

• Collaborators Not applicable.

• Contributors KC and KI wrote the paper. TK and RK reviewed the paper. All authors read and approved the final manuscript.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial, or not-for-profit sectors.

• Competing interests KC received lecture honoraria from Ethicon (Tokyo, Japan), Terumo (Tokyo, Japan), and Chugai Pharmaceutical (Tokyo, Japan). RK received research funding from Yakult Pharmaceutical Industry (Tokyo, Japan) and Chugai Pharmaceutical (Tokyo, Japan), as well as lecture honoraria from Japan Vaccine (Tokyo, Japan), MSD Japan (Tokyo, Japan), and Chugai Pharmaceutical (Tokyo, Japan).

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