In patients hospitalized with COVID-19 without end-organ failure, SARS-CoV-2 hyperimmune intravenous immunoglobulin (hIVIG) failed to be efficacious when given with standard of care including remdesivir. Variations may be seen in the safety profile of hIVIG based on the presence of endogenous neutralizing antibodies at entry.

• In this international randomized, double-blind, placebo-controlled trial, 593 hospitalized patients with COVID-19 without acute end-organ failure were randomized (1:1) to receive either hIVIG or an equivalent volume of saline as placebo, in addition to remdesivir, when not contraindicated, and other standard clinical care.

• The primary outcome was assessed at day 7 by a seven-category ordinal endpoint that considered pulmonary status and extrapulmonary complications and ranged from no limiting symptoms to death.

• Relative to placebo, there was no significantly greater odds of a more favorable outcome at day 7 in the hIVIG group; adjusted OR was 1·06 (95% CI 0·77–1·45; p=0·72).

• Composite safety outcomes at days 7 and 28 were defined based on deaths and adverse events, including organ failure and serious infections.

• Despite good tolerability of infusions, infusion reactions were more common in the hIVIG group (18·6% vs 9·5% for placebo).

• For both the groups, percentage with the composite safety outcome at day 7 was similar (hIVIG=24% vs placebo=25%; OR 0·98).

• For subgroups, there was no variation in the ORs for the day 7 ordinal outcome.

• However, findings showed heterogeneity of the treatment impact for the day 7 composite safety outcome: hIVIG was linked with greater risk than placebo for patients who were antibody positive (OR 2·21); for those who were antibody negative, estimated OR was 0·51.