Use of tocilizumab for severe hantavirus pulmonary syndrome: a MEURI case series with contextual comparisons

Hantavirus pulmonary syndrome is a rare zoonotic disease associated with high mortality, acute respiratory failure, shock, capillary leak, and systemic inflammation. Currently, no specific antiviral or immunomodulatory therapy has proven effective for routine clinical use. The current cruise-associated hantavirus outbreak motivated this early descriptive report from an ongoing, larger, pre-post study (ISRCTN72088243). We aimed to describe tocilizumab use under the Monitored Emergency Use of Unregistered and Investigational Interventions (MEURI) framework.

In this descriptive case series at Hospital Zonal de Bariloche Dr Ramón Carrillo, San Carlos de Bariloche, Argentina, patients with laboratory-confirmed severe hantavirus pulmonary syndrome and requiring intensive care unit (ICU) admission or assessment were eligible to receive tocilizumab in addition to standard supportive care, in accordance with the MEURI framework. Tocilizumab was administered to patients within 24 h of ICU admission or ICU-level evaluation as a single intravenous dose of 8 mg/kg, up to a maximum of 800 mg. During this time, five eligible patients could not receive tocilizumab because timely administration was not feasible due to drug unavailability or refractory shock at diagnosis. This case series represents the first report from the larger, ongoing, pre-post study (ISRCTN72088243). The main descriptive outcome was survival to ICU discharge in patients who received tocilizumab and patients who were eligible to receive tocilizumab but did not.

Between June 1, 2024, and May 5, 2026, 13 patients with laboratory-confirmed hantavirus pulmonary syndrome were evaluated for inclusion after institutional approval of the MEURI protocol. Ten met eligibility criteria for tocilizumab; five received tocilizumab and five did not. In the five eligible non-treated patients, two were diagnosed when they were already in refractory shock, precluding timely administration, and three did not receive tocilizumab because the drug was unavailable when treatment was being considered. Four of five tocilizumab-treated patients survived to ICU discharge. The fifth treated patient died after rapid progression to refractory shock. All five eligible non-treated patients died after ICU admission.

These observations suggest that IL-6 inhibition warrants further evaluation within the MEURI framework or analogous expanded-access frameworks, and, when feasible, collaborative randomised studies with standardised data collection.

None.

For the Spanish translations of the abstract see Supplementary Materials section.