AdvertisementPfizer plans to test a third dose of its COVID vaccine on infants and young childrenUpdated December 17, 2021Scott NeumanfacebookEmailA child, with parent in tow, arrives to receive the Pfizer COVID-19 vaccine for children 5 to 11 years old at London Middle School in Wheeling, Ill., last month. (AP)This article was originally published on December 17, 2021.