Text and Data Mining valid from 2019-06-24
Received: 8 January 2019
Accepted: 14 June 2019
First Online: 24 June 2019
Ethics approval and consent to participate
: Approval for this study was obtained by the institutional review board at Instituto Nacional de Enfermedades Respiratorias Ismael Cosio Villegas (INER; Mexico City, Mexico).
: Not applicable.
: The authors declare that they have no competing interests.