A study of Marine Corps recruits bound for Parris Island who quarantined at The Citadel found that despite strict conditions the coronavirus still spread, mostly through asymptomatic carriers.
More than 1,800 recruits participated in the study conducted this summer by the Naval Medical Research Center.
Fifty-one positive cases of COVID-19 were detected.
All of the positive cases were picked up by prescheduled tests and the virus was not detected as a result of additional screenings given to individuals who reported symptoms. Despite daily temperature readings and routine symptom checks, most of the sick recruits flew under the radar.
The study, published in the New England Journal of Medicine on Wednesday, found that nearly 1 percent of the recruits tested positive for COVID-19 when arriving at the military college even though they had self-quarantined before arriving.
Roughly 2 percent of recruits in the study also tested positive during the 14-day quarantine at The Citadel.
Cmdr. Andrew Letizia, deputy director of the Naval Medical Research Center’s infectious diseases directorate, was the lead researcher on the study.
He pointed out that the recruits were healthy men and women between the ages of 18 and 20. Despite the routine testing and strict measures, the virus managed to spread. And when one of them showed symptoms, the subsequent COVID-19 screening showed no virus.
Letizia said the findings illustrate the need for more frequent selective screening, often called "surveillance testing."
Expanding the screenings would allow researchers to study the spread in insulated populations, to see what outside factors are contributing to more infections.
With the group at The Citadel, no one was leaving campus which helped researchers realize it was coming from asymptomatic carriers.
"The takeaway is that there is a need for increased surveillance testing to monitor the spread," Letizia told The Post and Courier. "Behavioral changes are also essential."
Despite the strict conditions, coronavirus clusters also began to form at The Citadel during quarantine.
Genomes obtained from 32 of 51 recruits who tested positive for COVID-19 revealed that there was transmission among the ranks despite being tested before and while arriving on the campus.
Six independent transmission clusters found from other areas across the country were identified, according to The New England Journal of Medicine.
Researchers noted that there wasn't an explosion of cases during quarantine but the infection rate was heading in the wrong direction among the recruits.
While the protocol at The Citadel included “mask wearing, social distancing, and daily temperature and symptom monitoring," ultimately "shared rooms and shared platoon membership were risk factors for transmission,” the study detailed.
Military bases have struggled since the start of the pandemic on the best methods for containing the highly contagious virus.
When the COVID-19 pandemic hit, Parris Island had recruits sleeping in tents outside for two weeks.
The Post and Courier first reported that The Citadel began temporarily quarantining them on campus in May with an incentive of a $3 million contract. The school said it planned to host in-person classes for the 2020-21 school year and the arrangement would eventually end.
In July, the Marine Corps announced they were moving out of The Citadel and new Marines would be housed in hotels in Atlanta before being shipped to the Recruit Depot near Beaufort.
Letizia said the study was developed specifically to study the spread among Marines, but it could provide broader insight to public universities and colleges.
"It was a very similar population to universities consisting of young and healthy people from across the United States." Letizia said. "Young individuals don't realize they're infected when they show up. The findings do translate to other settings."