Features of COVID-19 in Children During the Omicron Wave Compared With Previous Waves in Madrid, Spain. Issue 5 (8th April 2022) - Tagarro, Alfredo; Coya, Olga-Nerea; Pérez-Villena, Ana; Iglesias, Beatriz; Navas, Adriana; Aguilera-Alonso, David; Moraleda, Cinta