Title : A parallel-group, multicenter randomized, double-blinded, placebo-controlled, phase 2\/3, clinical trial to test the efficacy of pyridostigmine bromide at low doses to reduce mortality or invasive mechanical ventilation in adults with severe SARS-CoV-2 infection: the Pyridostigmine In Severe COvid-19 (PISCO) trial protocol - Fragoso-Saavedra_2020_BMC.Infect.Dis_20_765