Martinez M, Martin FJ, Moreno S, Rodriguez F, Ruiz J, Canton R, De Lucas P, Garcia A, Garcia A, Hernandez T, Gomez J, Gonzalez del Castillo J, Martin MC, Molero JM, Santiago B, Antonio J, Barros C, Garcia de Viedma D, Martin C, Bouza E. Advantages and disadvantages of maintaining the mandatory use of masks in health centers and nursing homes in Spain. How and when is it justified to maintain it?