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The U.S. Navy hospital ship USNS Comfort admitted 182 patients during its 30-day mission to New York City in the spring of 2020. Almost 70 percent of those patients tested positive for COVID-19. Both the ship’s doctrine and its open-bay wards suggest that the vessel is not set up to control the spread of infectious disease. And yet, only six crewmembers tested positive for COVID-19 over the course of the one-month mission, with 12 more testing positive after the ship left New York.

Commander, U.S. Second Fleet asked CNA to assess how a hospital ship with over 1,200 crewmembers was able to return home from a national pandemic epicenter with just 1.4 percent of the staff testing positive for the virus. What lessons from that experience might inform further missions involving infectious disease, including biological weapons?

We concluded that the simple answer to why so few personnel contracted the virus is that everyone aboard — civilian and military — took the issue of viral containment seriously. They worked extremely hard to implement engineering and administrative controls that helped minimize hazards. Among several recommendations, we advise that U.S. Second Fleet and Military Sealift Command should integrate most of the mitigation strategies implemented in New York into a new a playbook for pandemic and infectious disease events. We recommend that responsible commands incorporate this playbook into quarterly hospital ship exercises.


In mid-March of 2020, when early epidemiologic models indicated a doomsday scenario for pandemic epicenters such as New York City, Seattle, and Los Angeles, a Northern Command fragmentary order activated USNS Mercy and USNS Comfort, the Navy’s two hospital ships. Comfort arrived in New York City on March 30, just as COVID-19 hospitalizations were peaking in the region. At that point, city officials reported over 38,000 total COVID-19 cases and 914 deaths. By the time the ship left New York, the incidence of the disease was over 4 times higher and deaths had increased 14-fold.

Given the fact that the hospital ship had limited infrastructure to isolate patients, its original mission was to provide treatment to non-COVID-19 patients, allowing regional medical facilities to concentrate on more numerous and serious COVID-19 cases. Within several days of its arrival, the ship’s mission changed to the care of any patient regardless of COVID status.


Analysts from CNA’s Health Analytics and Medical Readiness program interviewed Comfort crewmembers, including Military Sealift Command crew, military leadership, and key medical and engineering staff. We collected further qualitative data from military and civilian personnel who led activities at Second Fleet, Task Force-129. We also examined engineering and administrative changes, modeled the use of personal protective equipment (PPE), and conducted a review of literature focused on infectious disease and previous CNA studies on domestic disaster response.

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  • Publication Date: 6/1/2021