From the Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Pennsylvania, USA

Accepted for publication April 23, 2022

The author has no funding or conflicts of interest to disclose.

Address for correspondence: Stanley Plotkin, MD, Emeritus Professor of Pediatrics, University of Pennsylvania, Vaxconsult, 4650 Wismer Rd., Doylestown, PA 18902, USA. E-mail: [email protected].