key: cord-1051871-u0y6y7tk authors: Koeckerling, David; Pan, Daniel; Barker, Joseph title: Re: ‘Efficacy and safety of tocilizumab in COVID-19 patients: A living systematic review and meta-analysis' by Tleyjeh et al() date: 2021-02-05 journal: Clin Microbiol Infect DOI: 10.1016/j.cmi.2021.01.025 sha: 90216e938a08559701c63599f7e605316e938d2b doc_id: 1051871 cord_uid: u0y6y7tk nan To the Editor, 1 Tleyjeh and colleagues reported that tocilizumab reduces the risk of mechanical 2 ventilation in hospitalised patients with COVID-19, without definitive evidence of reduction 3 in short-term mortality or an increased risk of infection. [1] These are crucial findings which 4 could alleviate pressures faced by critical care services around the world. The UK government 5 has made tocilizumab and sarilumab widely available to patients with severe COVID-19 6 following a concerning surge in cases due to the emergence of a more-transmissible SARS- The proportion of spike protein mutations accumulated by VOC without the detection 10 of intermediary forms is much higher than expected from molecular clock estimates,[3,4] 11 initiating the exploration of potential evolutionary processes underlying its origin. Recent data 12 from the COVID-19 Genomics UK (COG) consortium found considerable within-host genetic 13 diversity of SARS-CoV-2 due to de novo mutations in random samples of infected patients. Efficacy and A Study to Evaluate the Safety and Efficacy of Tocilizumab in Patients With Severe 112 COVID-19 Pneumonia -Full Text View -ClinicalTrials Full Text View 115 -ClinicalTrials.gov n.d Tocilizumab in 118 Hospitalized Patients With COVID-19 Pneumonia Effect 121 of Tocilizumab vs Usual Care in Adults Hospitalized with COVID-19 and Moderate or 122 Severe Pneumonia: A Randomized Clinical Trial J o u r n a l P r e -p r o o f