Though the calendar is about to change, Friday had a distinctly 2020 feel: NFL games were postponed because of COVID-19 infections. The Rockettes Christmas show was canceled for the season. European governments imposed a spate of restrictions that ground travel to a halt and saw travelers lying low…

The Radio City Rockettes called off four performances scheduled for Friday because of breakthrough COVID-19 cases in the production, and plans for upcoming shows were still being assessed. The popular holiday program generally has four shows per day in December at Radio City Music Hall in Manhattan.

Dr. Stanley Weiss, a Rutgers University epidemiology professor, said officials need to react faster, citing a willingness to redefine fully vaccinated to include booster shots, for example.

“Everyone wants us to be through with this pandemic, but in order to get us through it, we can’t ignore the realities of what’s going on and what is needed,” Weiss said.