What we can learn from the Theodore Roosevelt outbreak

An investigation by the Navy and the Centers for Disease Control and Prevention into the outbreak of the novel coronavirus on board the San Diego-based aircraft carrier Theodore Roosevelt could yield data valuable not just to the military, but also to the greater scientific community in the race to better understand the virus, the Navy says.

The Roosevelt has been tied up in Guam for the last month as the virus spread throughout its crew.

Nearly 20 percent of the ship’s 4,845 sailors have tested positive for the novel coronavirus — 955 sailors. There are still a handful of results outstanding, the Navy said Friday.

Four sailors are in the hospital at Naval Base Guam. Another, Aviation Ordnanceman Chief Petty Officer Charles Thacker, 41, died from COVID-19 complications last week.

The Navy has been surveying members of the crew as part of its investigation. The Navy and CDC said previously they hoped to survey 1,000 sailors, obtaining saliva and blood tests.

Cmdr. Denver Applehans, a spokesman for the Navy Bureau of Medicine and Surgery, said in an email Friday the service asked 1,400 sailors to participate. About 400 did.

“It’s worth noting that the USS Theodore Roosevelt’s crew has been impacted by this virus harder than any other military unit and there are many competing demands on the crew to get the ship clean and ready to return to sea. We can’t overemphasize our appreciation for those who did volunteer,” Applehans wrote in an email.

The goal of the investigation, officials say, is to better understand the behavior of the virus and to apply those lessons to other Navy ships and military units.

The outbreak on the Roosevelt presents an opportunity to understand how the disease spreads in a relatively controlled environment, said Shane Crotty, a virologist and professor in the Vaccine Discovery Division at La Jolla Institute for Immunology in San Diego.

“It’s really an outstanding opportunity to learn more,” Crotty said. “That’s the type of scenario — a controlled environment, far fewer variables — it’s the kind of situation epidemiologists love because of the minimization of variables. For my side, we’re very interested in understanding viral immunology — the response (to the virus). In particular, how that would help vaccine development.”

The development of an effective vaccine for the novel coronavirus is seen by many as key to getting life around the world back to normal. The La Jolla Institute for Immunology is leading an international effort to collect antibody samples, which are important in vaccine development.

Blood samples from the Roosevelt investigation will be tested at the CDC’s laboratory in Atlanta using the agency’s new serology test, which can identify antibodies and tell researchers whether a person has been exposed to the virus even if they are showing no symptoms.

On the Roosevelt, Applehans said in the email, the rate of asymptomatic sailors testing positive for the virus is on the high end of what the CDC says can be expected in the general population.

“Approximately 50% of the sailors who tested positive so far on the (Theodore Roosevelt) have not shown symptoms of COVID-19,” Applehans said.

“The CDC has said that roughly 25% of COVID-19 infections are asymptomatic across all age groups. Given that the Sailors are generally younger and healthier than the general population across all age groups, 50% or even slightly above may be appropriate or expected.”

Applehans said the Navy expects to gain more clarity on asymptomatic carriers and virus transmission.

Among the questions Crotty has is whether asymptomatic people who test positive for the virus develop an immune response — something the CDC’s antibody test might reveal.

“From my area in expertise, for us thinking about vaccine development and immunity, one missing piece is: do asymptomatic cases develop immune responses or not?” Crotty said. “The blood tests on the sailors should reveal that pretty quickly.”

That immune response — one that effectively fights off the virus — would tell researchers what an effective response looks like.

“Right now, there are over 80 different vaccine candidates,” Crotty said. “Once you have information in hand on what a good immune response looks like, it can help point out what vaccine strategy works. That’s really valuable information — they’re going to have very high-quality data about true asymptomatic cases.”

On the Roosevelt, and unlike anywhere else with an outbreak, 100 percent of those potentially exposed to the virus have been tested.

In addition to the blood and saliva samples taken from sailors, officials had volunteers fill out surveys to track their locations on board the ship.

The Navy’s surgeon general, Rear Adm. Bruce Gillingham, said last week one of the goals is to determine how much the virus spread without sailors showing symptoms.

“Because of the pre-symptomatic transmission, we believe that it probably passed through the ship quite freely and was initially unrecognized,” Gillingham said.

The Roosevelt pulled into Guam March 28 as the virus spread quickly among its crew.

The first two cases of the virus were found among two members of the ship’s air wing, a Navy official told the Union-Tribune. However, because the two cases came to light 15 days after a port visit to Vietnam, Gillingham could not say how the virus got on board.

He said that is not the intent of the investigation.

PACIFIC OCEAN - JULY 15: In this handout released by the U.S. Navy, The aircraft carrier USS Theodore Roosevelt (CVN 71) transits the Pacific Ocean. Theodore Roosevelt is conducting routine operations in the Eastern Pacific Ocean. (Photo by U.S. Navy via Getty Images)

(U.S. Navy via Getty Images)

“The intent of investigation is not to get to the source; it’s to better understand the behavior of the virus going forward,” he said.

The Navy also reported some quarantined sailors tested positive for the virus more than 14 days after testing negative.

Experts point to the virus’ long incubation period as being one of the key factors making its spread difficult to slow.

While the Navy’s interests in the investigation lean more toward getting back to sea and conducting operations, Applehans said the CDC will share its data with researchers on the civilian side.

“Our partners at CDC will share that information with the broader scientific community as is useful,” Applehans said. “We won’t know for sure until the specimens are processed and the data analyzed, but everything we can learn about this new virus is useful and contributes to the larger body of scientific knowledge that will increase our understanding of how we can prevent, treat, and mitigate COVID-19.”

Results from the CDC are not due for at least one month.