Shares of Pfizer Inc. /zigman2/quotes/202877789/composite PFE +0.89% rose 2.1% and of Germany-based partner BioNTech SE /zigman2/quotes/214419716/composite BNTX -2.96% climbed 4.2% in morning trading Friday, after Health Canada authorized use of the companies' COVID-19 vaccine in children 5 to 11 years old. That's the first vaccine authorized in Canada for that age group. The companies' vaccine has been authorized for children 12 to 15 years old since May and for people at least 16 years old since December. The news comes on the same day that the U.S. Food and Drug Administration OK'd the use of COVID-19 booster shots for both the Pfizer-BioNTech and Moderna Inc. COVID-19 vaccines for all adults. Pfizer's stock has gained 7.6% over the past three months while BioNTech shares have shed 14.0%, and the S&P 500 /zigman2/quotes/210599714/realtime SPX -1.00% has tacked on 6.9%.