Sailors annotate covid-19 symptoms Saturday during door-to-door daily medical checks aboard the USS Theodore Roosevelt at Naval Base Guam. (Jordan E. Gilbert/Navy/AFP/Getty Images)

When the coronavirus roared through the claustrophobic bowels of the USS Theodore Roosevelt, it crippled the aircraft carrier, sickened hundreds of the 4,800 sailors and ultimately ended the tenure of the Navy secretary.

But the ship’s odyssey is far from over — and the military’s biggest covid-19 crisis could yield an epidemiological gold mine as researchers worldwide race to answer questions about the virus.

At least 777 Roosevelt sailors have been infected, and the rate of asymptomatic infection is about 50 percent, the Navy said Wednesday. In contrast, the general population rate is about half that — as high as 25 percent, the Centers for Disease Control and Prevention has said.

And now, as experts and governors are struggling to understand the role of asymptomatic transmission to hone guidance and economic recovery options, the ship infections could reveal new clues of how the virus percolates through communities, epidemiologists said.

The Navy has called for 1,000 volunteers from the crew to submit to swabs and blood tests to better “connect the dots” of the transmission, the Navy surgeon general, Rear Adm. Bruce Gillingham, told reporters last week.

“It is an opportunity to understand more,” said Albert Ko, department chair and professor of epidemiology and medicine at the Yale School of Public Health. “Unfortunately, outbreaks serve a purpose. They can teach us how to prevent them.”

One big mystery of the virus is whether people develop an immunity and, if so, for how long, Ko said.

The serology tests would pinpoint antibodies created by the immune system after infection, and closely following their presence will help researchers determine whether immunities have or can be developed.

The sailors are a captive audience and can be nudged by leadership — or in military parlance, “voluntold” — to submit to tests, and researchers will be able to easily track and recall participants for follow-ups, Ko said.

There is also a trove of data inherent to military life: a meticulous accounting of where everyone is at nearly all times.

Ships in particular have many duties carried out in the same place, and studying where clusters are found — and where they are not — can help inform what facilitates and reduces transmission, said Timothy Brewer, a professor of epidemiology and medicine at the University of California at Los Angeles.


An F/A-18F Super Hornet launches from the USS Theodore Roosevelt in March. (Nicholas V. Huynh/Navy/AP)

Some duty areas may be less ventilated or more crowded, Brewer said, or staffed at different times of the day. And understanding how the virus circulated with those variables can help reveal how it moves through other close-contact spaces, such as hospitals, elder-care facilities and homes, he said.

“The more and exact data you have, the better you can interpret it and come up with conclusions,” Brewer said.

One fortunate stroke for researchers, Ko said, is the military’s health records system. Service members are screened before enlistment, and every medical interaction is recorded in a voluminous file. Cross-referencing infections and their severity with underlying conditions could prove useful, he said.

Navy medical officers did not provide the age range of infected sailors, but most enlisted sailors are under 30.

There is a “knowledge gap” about the virus’s impact among younger people, particularly those under 20, Ko said, and some sailors aboard the ship could help researchers fill in the data.

Younger people may have a greater role in spreading the virus than previously understood, he said, because while people with symptoms are quarantined, carriers without symptoms may unknowingly infect many others.

The tests will take about a week to conduct and be paired with questionnaires that provide data on living conditions and symptoms, Navy health officials said.

The tests will be sent to the CDC for analysis and shared with the White House coronavirus task force to aid the broader scientific community, Gillingham said.

The Navy has yet to clearly explain how the virus arrived on board in the first place. Officials have given conflicting answers about whether they believe air-wing members brought it aboard or whether it was contracted during a port visit in Vietnam.

One sailor has died of the infection and others were hospitalized, though no sailors were in intensive care as of Wednesday, the Navy said.

Ko and Brewer cautioned that there are limits to how instructive the ship’s outbreak can be.

Sailors spend months in closer contact than most people will ever experience, Ko said. They eat elbow to elbow, crowd into berthing spaces to sleep in bunks stacked high and pass one another in narrow passageways where they are lucky to get six inches apart from others, much less six feet.

Studies evaluate populations to see whether they can be compared with other groups, Brewer said, and ships of sailors — mostly young, mostly healthy and mostly male — don’t have many peer groups beyond other sailors.

That doesn’t erase the value, Brewer said: “It means you have to be careful.”

But Ko, who is also advising the Connecticut governor’s office on when to reopen the state’s economy, said the ship’s journey is one more piece of evidence demonstrating the pernicious effect of phantom infections.

“A lot of plans are based on testing people who are sick, isolating them, tracing their contacts and quarantining them,” he said. “If there is a lot of asymptomatic transmission, then it makes that strategy much more difficult.”