COVID-19, SARS-CoV-2, delay, surgery, timing, Adolescent, Adult, Aged, Aged, 80 and over, COVID-19, Child, Child, Preschool, Cohort Studies, Female, Humans, Infant, Internationality, Male, Middle Aged, Practice Guidelines as Topic, Prospective Studies, SARS-CoV-2, Surgical Procedures, Operative, Time, Young Adult