Symptom screening may be inadequate to identify SARS-CoV-2
infections and slow spread of the disease, a new study that examined the novel coronavirus disease a correctional and detention facility in Louisiana suggests.
Highlighted recently in the US Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report
, the study found that about one-fourth of coronavirus 2019 (COVID-19) cases at the detention facility were identified through serial testing, and a high proportion of cases were asymptomatic and presymptomatic.
The study was conducted after a staff member at a Louisiana correction and detention facility developed symptoms of COVID-19 on March 29 and later tested positive for the disease. Between April 2-May 7, officials identified 2 additional cases among staff members and 36 cases among people detained at the facility, prompting an investigation by the CDC and the Louisiana Department of Health.
Further testing conducted on May 7, May 11, and May 21 identified 71 additional cases of COVID-19, including 32 (45%) who reported no symptoms at the time of testing, and 18 (25%) who had previously received negative test results.
“Serial testing of contacts from shared living quarters identified persons with SARS-CoV-2 infection who would not have been detected by symptom screening alone or by testing at a single time point,” the study noted.
The tests were conducted among 98 people quarantined in 5 dormitories because of exposure to the SARS-CoV-2 virus. On May 7, 53 (54%) tested positive for SARS-CoV-2. Among those who tested negative, 16 (36%) tested positive on the May 11, and 2 more tested positive on May 29.
The most common symptoms reported among those in quarantine were headaches and loss of smell. None of the patients required hospitalization.
Out of 71 total cases:
• 3 were presymptomatic at the time of testing
• 29 were asymptomatic
• 37 reported symptoms before testing
• 11 reported symptom onset 2 weeks or less before testing
• 19 reported symptom onset more than 2 weeks before testing
Among the 27 who tested negative:
• 18 reported COVID-19-like symptoms in the 2 months before testing
• 8 reported loss of smell
• 7 reported loss of taste
“These findings suggest ongoing transmission among quarantined persons living in congregate settings; therefore, serial testing of contacts of persons with COVID-19 in correctional and detention facilities can identify asymptomatic and presymptomatic persons who would be missed through symptom screening alone,” investigators wrote.
The study confirms that some patients could be infected with SARS-CoV-2 for weeks and potentially spreading the disease without knowing it. Serial testing could be used to identify COVID-19 cases and control the spread of the disease in other group settings such as long-term care facilities and homeless shelters after an initial case is identified.
Limitations of the study include that serial testing didn’t begin until 2-4 weeks after the initial COVID-19 case was identified, during which time transmission of the disease is likely to have occurred; about one-third of those who tested negative had reported symptoms, suggesting they may have already recovered from the disease before serial testing began; and testing was limited to those detained and not staff members they came in contact with, who may have contributed to transmission. The study was also limited to a portion of 1 facility and can’t be generalized.
Prisons have been identified as a potential sites for rapid spread of the disease. The number of cases at Riker’s Island jumped to more than 200 just 2 weeks after the first case was identified there in mid-March, leading some health experts to urge the prioritization of prisons
in combating the spread of the disease.
Nursing homes also have drawn attention, as the disease has been shown to spread quickly among residents of facilities in close contact with one another. More than half of residents who tested positive for the virus at one such facility were asymptomatic
at the time of the testing.
As more is learned about how the disease is spread, the CDC has updated recommendations. On June 13, CDC recommended testing for all those who have been close contacts of someone confirmed to be infected with SARS-CoV-2, including those without symptoms, and broader testing to prevent the spread of the disease in high-risk settings.
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