European Resuscitation Council COVID-19 guidelines executive summary by Roehr, CC, Nolan, JP, Monsieurs, KG, Bossaert, L, Böttiger, BW, Greif, R, Lott, C, Madar, J, Olasveengen, TM, Semeraro, F, Soar, J, Van de Voorde, P, Zideman, DA, Perkins, GD, European Resuscitation Council COVID-Guideline Writing Groups