Most of the nearly 5,000 members of the USS Theodore Roosevelt crew has been tested for COVID-19, and a majority of those who tested positive had no symptoms at all, according to Reuters.
More than 600 sailors have tested positive for the disease caused by the novel coronavirus SARS-CoV-2, and 60% of those sailors were asymptomatic.
"With regard to COVID-19, we're learning that stealth in the form of asymptomatic transmission is this adversary's secret power," said Rear Adm. Bruce Gillingham, surgeon general of the Navy, Reuters reported.
The situation aboard the USS Theodore Roosevelt gained national attention when the ship's former captain, Brett Crozier, sent a letter to military leaders asking for help to deal with a small but growing coronavirus outbreak on the ship.
Crozier was fired by former Navy Secretary Thomas Modly for sending the message through unclassified channels to multiple recipients. Shortly after that, Modly resigned due to backlash from comments he made to the ship's crew about Crozier.
The percentage of sailors with the virus but no symptoms is cause for concern for the Navy, as sailors around the world are in tight quarters on ships where the virus could spread without anyone even knowing that it's present. One sailor from the USS Theodore Roosevelt has died, and five others are hospitalized.
Asymptomatic spread is also a concern for President Donald Trump, state governors, and the public health officials tasked with deciding when to reopen businesses and allow public gatherings. The United States is still mostly testing patients who display significant COVID-19 symptoms, meaning there is no way to know or even accurately estimate how many asymptomatic cases exist.
The data from the USS Theodore Roosevelt tests give some insight into the potential that many young, otherwise healthy people in the general population could be infected and may be spreading COVID-19 without their knowledge. It could also mean that the virus' actual mortality rate is much lower than currently believed.
"The findings are of enormous interest because the proportion of people who are asymptomatic is just simply not known," said William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center, to Reuters.