Purpose Interleukin-6 (IL-6) levels discriminate between patients with mild and severe COVID-19, making IL-6 inhibition an attractive therapeutic strategy. We conducted a systematic review, meta-analysis, trial sequential analysis (TSA), and meta-regression of randomized-controlled trials to ascertain the benefit of IL-6 blockade with tocilizumab for COVID-19. Methods We included randomized-controlled trials (RCTs) allocating patients with COVID-19 to tocilizumab. Our control group included standard care or placebo. Trials co-administering other pharmacological interventions for COVID-19 were not excluded. Primary outcome was 2830day mortality. Secondary outcomes included progression-to-severe disease defined as need for mechanical ventilation, intensive-care unit (ICU) admission, or a composite. Results We identified 10 RCTs using tocilizumab, 9 of which reported primary outcome data (mortality), recruiting 6493 patients with 3358 (52.2%) allocated to tocilizumab. Tocilizumab may be associated with an improvement in mortality (24.4% vs. 29.0%; OR 0.87 [0.741.01]; p =0.07; I 2 =10%; TSA adjusted CI 0.661.14). Meta-regression suggested a relationship between treatment effect and mortality risk, with benefit at higher levels of risk (logOR vs %risk beta=0.018 [0.037 to 0.002]; p =0.07). Tocilizumab did reduce the need for mechanical ventilation and was associated with a benefit in the composite secondary outcome but did not reduce ICU admission. Conclusions For hospitalized COVID-19 patients, there is some evidence that tocilizumab use may be associated with a short-term mortality benefit, but further high-quality data are required. Its benefits may also lie in reducing the need for mechanical ventilation. Supplementary Information The online version contains supplementary material available at 10.1007/s00134-021-06416-z.

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