The travelers had returned to North America via Canada and were taken to the military base rather than entering the United States directly from Congo, officials said. U.S. health authorities coordinated the quarantine with the Department of Defense, which issued at least two internal notifications regarding the operation.

The group of 14 American citizens was quarantined for four days at a U.S. military base in New York State after returning from the Democratic Republic of Congo, where an Ebola outbreak is ongoing, according to Defense Department notifications reviewed by Reuters.

Officials emphasized that none of the travelers showed symptoms of Ebola, and they were assessed as not at risk of transmitting the virus at the time of quarantine, according to the Defense Department memo circulated to lawmakers. The memo stated there was “no danger to the public or base personnel,” framing the quarantine as a precautionary measure to contain any potential risk. Records and sources confirmed that none of the 14 developed symptoms during their four-day stay at the base.

The quarantine followed enhanced federal measures aimed at preventing the introduction of Ebola into the United States from affected regions. A “do-not-board” order issued in July requires U.S. citizens in Congo to quarantine for at least 21 days before they can return to the U.S. via commercial flights, according to multiple reports. However, current policies do not impose a blanket ban on returning citizens entering the U.S. through land crossings such as from Canada, which was the route taken by this group, sources said.

The Defense Department notifications made clear that the travelers could not return directly from Congo to the United States, reflecting tightened controls on direct inbound travel from Ebola-affected regions. These measures are part of the Trump administration’s efforts to “keep out individuals it deems at risk of Ebola,” even when those individuals are U.S. citizens, according to official communications reviewed by Reuters. The policies require medical clearance and completion of quarantine before travelers from Ebola zones are permitted to enter the country by commercial air.

The Democratic Republic of Congo has been experiencing an Ebola outbreak that has persisted over time, prompting heightened international monitoring and travel precautions, officials said. Public health experts note that Ebola has an incubation period of up to 21 days, which underpins the quarantine protocols and the 21-day requirement for travelers returning from affected areas. The U.S. quarantine of the 14 travelers was a preventive measure aligned with these incubation-period-based protocols, rather than a response to confirmed infection.

Legal and civil liberties concerns have been raised regarding the restrictions placed on American citizens returning from the Congo. Some legal analysts and public health experts have expressed unease about policies that appear to deny or delay entry to U.S. citizens, even when they are asymptomatic. Critics argue that such measures may conflict with constitutional protections and established norms regarding the right of citizens to re-enter their own country, according to legal commentaries published in recent months.

The current federal quarantine and travel restrictions draw on precedents set during the 2014 Ebola outbreak in West Africa. At that time, Connecticut’s governor authorized a mandatory 21-day quarantine for anyone with direct contact with Ebola patients, even if asymptomatic. Similarly, the governors of New York and New Jersey imposed mandatory 21-day quarantines on certain air travelers returning from West Africa who had contact with Ebola patients. New York later modified its policy to allow home quarantine with twice-daily health checks and some compensation for lost wages, reflecting efforts to balance public health control with civil liberties.

The quarantine of the 14 Americans at the New York military base fits into a broader trajectory of increasingly formalized Ebola travel screening and quarantine protocols in the United States since 2014. The Department of Defense and U.S. health officials continue to monitor travelers from Ebola-affected regions closely as part of ongoing efforts to prevent the virus from reaching American communities, according to officials involved in the operation.

The advisory groups also supported evaluating combination therapy using a monoclonal antibody plus remdesivir to determine whether dual-agent regimens improve patient outcomes. None of these treatments is currently licensed specifically for Bundibugyo Ebola, but they were selected based on promising preclinical or prior clinical data against Ebola viruses, according to WHO.

WHO expert groups recommended prioritizing three candidate therapeutics for clinical trials among confirmed Bundibugyo virus disease (BVD) cases: the monoclonal antibodies MBP134 and Maftivimab®, as well as the antiviral remdesivir, the agency said in a May 28 statement.

WHO officials emphasized that these candidate therapies must be administered exclusively within structured clinical trials that include standardized protocols, data collection, and ethical oversight, rather than as part of routine care. Access to these investigational treatments will be limited to patients with laboratory-confirmed BVD in affected areas of the Democratic Republic of the Congo (DRC) and Uganda, the two countries currently experiencing cases, WHO said.

On the vaccine front, WHO experts identified a single-dose recombinant vesicular stomatitis virus (rVSV) Bundibugyo vaccine developed by the International AIDS Vaccine Initiative (IAVI) as the most promising candidate for prevention. According to WHO, this vaccine is expected to require approximately seven to nine months before doses are ready for clinical efficacy trials. A second candidate vaccine, ChAdOx1 Bundibugyo, developed by Oxford University in collaboration with the Serum Institute of India, could be available for efficacy assessment in about two to three months, pending additional animal data to support further prioritization, WHO officials said.

WHO cautioned that the only currently licensed Ebola vaccine, Ervebo (rVSV-ZEBOV-GP), which targets the Zaire Ebola virus species, is not approved for Bundibugyo virus disease. Evidence for cross-protection against Bundibugyo is limited and inconclusive, so WHO advised restricting its use to carefully designed research settings during the current outbreak.

For post-exposure prophylaxis (PEP) among contacts of confirmed or probable BVD cases, WHO experts prioritized the oral antiviral obeldesivir for evaluation in clinical trials. Planned research involves administering obeldesivir tablets to identified contacts and monitoring whether the treatment prevents disease development. WHO noted, however, that effective PEP implementation depends on strong contact-tracing systems, which remain operationally challenging in some affected areas of the DRC.

WHO is working closely with the governments of the DRC and Uganda to facilitate and implement clinical research evaluating the prioritized treatments and vaccines during the ongoing Bundibugyo outbreak. The agency convened multiple expert and advisory groups focusing on epidemic-prone diseases, ethics, regulatory issues, and clinical management to review evidence and recommend a research strategy, according to WHO.

The current approach builds on lessons learned from previous Ebola vaccine trials. Notably, Uganda’s Ministry of Health and WHO launched the first-ever clinical efficacy trial for a Sudan-species Ebola vaccine on February 3, 2025, in Kampala. That trial used a ring-vaccination cluster-randomized design to evaluate a single-dose rVSV candidate vaccine among contacts and contacts-of-contacts of confirmed Sudan virus disease cases. Prior Phase 1 safety and immunogenicity data supported the trial design.

WHO’s Global Advisory Committee on Vaccine Safety has reported reassuring safety profiles for licensed Ebola vaccines, including Ervebo and the Ad26.ZEBOV/MVA-BN-Filo regimen, with more than 6,500 adults and 649 children vaccinated in various studies. The rate of grade 3 fever in children within seven days post-vaccination was less than 1.5%, according to WHO records. Earlier trials such as the “Ebola ça Suffit” study demonstrated high protection with rVSV-EBOV in West Africa, establishing ring vaccination and rapid deployment as effective outbreak strategies.

The rVSV Bundibugyo vaccine candidate is under development by IAVI, an international nonprofit organization with prior experience in rVSV-based Ebola vaccines. The ChAdOx1 Bundibugyo vaccine is being developed by Oxford University in collaboration with the Serum Institute of India, leveraging adenovirus-vector platforms similar to those used in other viral vaccines. Animal studies for the ChAdOx1 candidate are already underway, with WHO describing it as a promising candidate if animal data support further advancement.

WHO noted that the new Bundibugyo trials are planned amid an ongoing outbreak in the DRC, with cross-border spread to Uganda prompting an accelerated research response. While the licensed Ervebo vaccine is available for Zaire Ebola virus, no proven or licensed vaccine exists for Bundibugyo virus disease, underscoring the need for new, species-specific vaccine and therapeutic trials.

According to WHO briefings and external reports, doses of the ChAdOx1 Bundibugyo vaccine could be ready for clinical trials within two to three months, while the rVSV Bundibugyo candidate may take approximately seven to nine months to reach trial readiness. WHO and collaborating scientists have stressed that the effectiveness of these new products is not yet known, making formal clinical trials essential both to manage the current outbreak and to build an evidence base for future responses.

The outbreak, which had previously been reported at 91 deaths out of 350 suspected cases, is centered in eastern Democratic Republic of Congo, with confirmed transmission in Ituri province. According to the World Health Organization, 30 cases have been confirmed in Ituri, while the broader suspected caseload exceeds 500, with one official estimate at 513 suspected cases. Health authorities have expressed concern that the outbreak has spread beyond a single locality, raising the possibility of wider geographic transmission.

Health Minister Samuel Roger Kamba said the 131 deaths reported as of May 19, 2026, represent fatalities identified in the community and are not all necessarily confirmed Ebola deaths.

The World Health Organization declared the outbreak a public health emergency of international concern, citing the rapid pace and scale of transmission. This designation was supported by the Africa Centres for Disease Control and Prevention, which termed the situation a continental public health emergency. WHO officials clarified that the outbreak is not being treated as a pandemic but as a significant cross-border public health threat. An emergency meeting was convened by WHO to coordinate the international response.

The Ebola virus strain involved is identified as the Bundibugyo strain. Health reports indicate there is no approved vaccine or therapeutic treatment for this strain, a factor contributing to heightened concern among scientists and health agencies. WHO and the U.S. Centers for Disease Control and Prevention emphasized the need for rapid surveillance, noting that the outbreak may be expanding faster than case confirmation can keep pace. The strain is described as highly contagious and particularly dangerous in settings with weak containment measures.

Cross-border spread has been confirmed with two cases reported in Uganda, including one death. WHO stated that the Ugandan cases involved individuals who had traveled from DR Congo. In response, WHO has advised cross-border screenings between DR Congo and Uganda to help limit further spread. The movement of people across borders is central to the current response strategy.

A U.S. citizen and doctor working in DR Congo was confirmed to have contracted Ebola. The medical missionary organization Serge identified the patient as one of its doctors who had been exposed through work in the outbreak area. Germany announced readiness to receive and treat the American patient. Reports from CBS indicated that at least six Americans may have been exposed to the virus, though this figure has not been formally confirmed by WHO or CDC.

The CDC stated that the risk to the United States remains relatively low but that preventive measures are in place. U.S. authorities have begun monitoring travelers arriving from affected regions and have imposed entry restrictions on non-U.S. passport holders who have been in Uganda, DR Congo, or South Sudan within the past 21 days. The U.S. issued a Level 4 travel warning for DR Congo, its highest advisory level, discouraging travel to the area. Additionally, screening of air passengers from outbreak-hit areas has commenced, and visa services for some travelers from affected countries have been temporarily suspended.

The outbreak was first confirmed in late the previous week before the May 19 update. Health officials have indicated that the number of cases may continue to rise as investigations and surveillance efforts proceed. The lack of an approved vaccine and the rapid spread of the Bundibugyo strain remain key challenges for containment efforts. WHO and CDC continue to coordinate international response activities aimed at limiting the outbreak’s expansion.