COVID-19 outbreaks in long term care facilities for elderly during periods of Delta and Omicron variants predominance in Spain. Boletín Epidemiológico Semanal, Madrid, v. 31, n. 4, p. 274–288, 2023. DOI: 10.4321/s2173-92772023000400007. Disponível em: //revista.isciii.es/index.php/bes/article/view/1333. Acesso em: 10 feb. 2026.