Hantavirus Global Situational Briefing — May 25, 2026

The cluster count holds at 12 cases and three deaths for a third consecutive day, but two significant regulatory and clinical-management moves shifted the policy picture on May 24: the US Department of Health and Human Services issued a targeted PREP Act declaration unlocking experimental use of the antiviral favipiravir for Andes virus, and the Netherlands cleared a separate Ebola-suspect admission at Radboudumc — an unrelated alarm that had run in parallel since May 23. Kansas added a new layer of uncertainty when three non-passenger contacts transferred to hospital under unexplained circumstances. Rotterdam decontamination enters Day 8 with the RIVM post-clearance inspection still pending.

HHS invokes PREP Act for favipiravir

On May 22, HHS Secretary Robert F. Kennedy Jr. signed a targeted PREP Act declaration specifically covering favipiravir — an RNA-active antiviral originally developed for influenza — for use against Andes hantavirus. The declaration was published in the Federal Register on May 23 (docket 2026-10539) 1 and is in effect through July 18, 2026.

The declaration's scope is narrow. It covers only favipiravir, only in the context of the MV Hondius outbreak and its transmission chain, and does not extend to vaccines or other antivirals. Kennedy clarified in a May 23 statement that the action imposes no mandatory requirements and does not open liability shields for novel mRNA products 2. The drug's relevance here is animal-model data showing 100% survival in rodents challenged with lethal doses of Andes virus. No human clinical data for this indication exists.

The practical significance is procedural: the declaration removes liability barriers that had slowed expanded-access applications, allowing physicians treating severely ill patients — particularly France's ECMO case — to request compassionate use without institutional legal exposure. Independent commentary has noted favipiravir carries its own risk profile, including teratogenicity concerns, which the declaration does not resolve 3.

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Radboudumc Ebola suspect: negative

The patient admitted to Radboud University Hospital in Nijmegen on May 23 with low clinical suspicion for Ebola has tested negative for the virus 4. The admission had prompted concern given the concurrent DRC Bundibugyo Ebola outbreak — for which WHO raised regional risk to "very high" on May 23, with 82 confirmed cases and roughly 750 suspected across DRC and Uganda. The Dutch patient's clearance removes one variable, though WHO's broader DRC assessment remains unchanged.

MV Hondius cluster status

Case count: 12 total (10 confirmed, 2 probable), 3 deaths. No new confirmed cases since May 22. No deaths since May 2.

Rotterdam decontamination — Day 8: EWS Group's fumigation and decontamination protocol is ongoing. The 25 remaining crew members and 2 RIVM medical staff are aboard. RIVM's post-clearance inspection, which must pass before Oceanwide Expeditions can restart passenger operations, has not yet been announced 5. The June 13 restart remains the operational target, with May 29 and June 5 sailings already canceled.

Case 12 — Dutch crew member: Still hospitalized. Confirmed by both RIVM and Erasmus MC 6.

38 Filipino crew (OFWs): All 38 Overseas Filipino Workers remain PCR-negative and asymptomatic as of May 25, according to the Philippine Department of Migrant Workers 7. They remain in 42-day precautionary quarantine in the Netherlands.

France: mandatory hospital isolation confirmed

France is maintaining mandatory hospital isolation for all 26 contacts (four MV Hondius passengers plus two individuals who shared a flight with a deceased passenger). Every contact has so far tested negative. French Health Minister Stéphanie Rist reaffirmed the strict protocol — resisting earlier moves toward home quarantine — after WHO announced Case 12 on May 22 8. All 26 are tested three times weekly; the decision was informed by epidemiological modeling shared with the government.

The ECMO patient — a 65-year-old woman at Hôpital Bichat AP-HP, Paris — remains on extracorporeal life support. No clinical update has been issued since May 12. She has now been on ECMO for approximately 13 days.

Spain: revised quarantine protocol

Spain's Public Health Commission approved a revised quarantine protocol for the 15 contacts at Gómez Ulla Hospital: the first 28 days are spent in hospital isolation, with transfer to home permitted for the final 14 days — provided the contact is asymptomatic and PCR-negative and can guarantee isolation conditions at home. Transfers use dedicated medical transport; both patient and driver must wear FFP2 masks 9.

The confirmed Spanish case — a 70-year-old who was approaching discharge earlier this week — remains in Spain's High-Level Isolation and Treatment Unit (UATAN) until full clinical recovery. The provisional second case (mild fever, respiratory symptoms in another passenger) has not been confirmed; Spain's 13 other contacts continue to test negative.

US: CDC holding on quarantine end date; Kansas contacts hospitalized

The 18 American passengers at the National Quarantine Unit at the University of Nebraska Medical Center remain asymptomatic. CDC has not yet determined whether they will be released before the full 42-day period ends on May 31 10. CDC incident commander Dr. David Fitter noted that 41 Americans total are under monitoring across 11 states, with zero positive cases.

Passengers disembarking from MV Hondius at Granadilla port, Tenerife, May 10, 2026 — MV Hondius passengers evacuated at Tenerife, May 10 8

The more notable development came from Kansas: three individuals who are not MV Hondius passengers but had high-risk exposure abroad — meaning contact with a confirmed cluster case — were transferred to hospital for observation. CDC confirmed awareness and is monitoring; no explanation of symptoms or clinical trigger has been issued 8. This is the first time non-passenger high-risk contacts have been escalated to hospital-level monitoring in the US.

Angela Perryman's federal quarantine order runs through May 31. The CDC's authority to detain under ANDV — classified for quarantine purposes as severe acute respiratory syndrome given Andes virus's absence from the presidential quarantinable disease list — remains untested in court 11.

WHO and international response

WHO is not considering a PHEIC declaration. Director-General Tedros stated the outbreak is under control and the global risk for the general public remains low, with no evidence of increased transmissibility or pathogenicity 8. WHO is running a multi-country study covering approximately 20 nations to determine the duration of viral shedding and detectability. The origin investigation — focused on Ushuaia pre-embarkation exposures — continues, with Argentine scientists planning sample collection trips in the coming days; results are expected in roughly four weeks.

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The Oxford/ISARIC clinical study entered its fourth day. The study is tracking more than 20 British nationals, with high-containment sample analysis handled by UKHSA RIPL and MRC Glasgow CVR.

Netherlands: Radboudumc protocol-breach quarantine continues

Twelve Radboudumc employees placed in six-week precautionary quarantine after a protocol breach during Case 12's initial treatment have had blood tests confirm they are not infectious 8. Despite the negative serology, they will complete the full six-week precautionary period, expected to end in late June.

Americas endemic surveillance

Argentina's Bulletin Epidemiológico Nacional (BEN) SE19 is expected around May 26 and will update the cumulative ANDV case count, which stood at 102 cases and 32 deaths through SE18. Chile remains at 41 cases and 14 deaths (34% CFR). The 150-trap rodent survey in Ushuaia forests and Tierra del Fuego National Park collected May 19–21 remains at the Malbrán Institute in Buenos Aires for analysis; results are expected within the month.

Watchlist for May 26

RIVM post-decontamination inspection announcement (Rotterdam Day 9)
Argentina BEN SE19 publication
France ECMO patient update (13+ days on support)
Spain second provisional case confirmatory PCR result
Kansas hospitalized contacts — clinical updates
WHO formal DON update incorporating Case 12 (still pending since May 13 DON-601)
Favipiravir compassionate-use application outcomes (if any)