Serial Testing Found COVID-19 Symptom Checks Missed in a Louisiana Jail, 2020

By May 2020, a correctional and detention facility in Louisiana had found 36 COVID-19 cases among the people held there, all through daily symptom and temperature checks, and quarantined the five dormitories where they had lived. Then investigators tested everyone in those dormitories — three times over two weeks. Of the 98 people there, 71 turned out to be infected. Nearly half had no symptoms when tested, and a quarter tested positive only after first testing negative.

CDC's summary of the findings. Credit: CDC, Morbidity and Mortality Weekly Report.

The outbreak

The facility held about 700 people in 15 dormitories. A staff member fell ill on March 29, 2020, and two more staff cases followed. The first case among incarcerated people was found on April 7; by May 7, daily monitoring with temperature and oxygen checks had found 35 more symptomatic cases in five dormitories, three of whom were hospitalized. All patients were moved at once to another facility for medical isolation and care.

Testing everyone, three times

From May 7 to 21, the Louisiana Department of Health and CDC tested all 98 people in the five quarantined dormitories (median age 33) with nasal swabs:

• Day 1 (May 7): everyone tested; 53 (54 percent) were positive.
• Day 4 (May 11): those negative on day 1 were retested.
• Day 14 (May 21): those still negative were tested again, at the end of quarantine.

Results came back within 24 hours, and people were moved to medical isolation or kept in quarantine accordingly.

Dormitory A, where the first case had been found most recently before testing began, had the lowest attack rate and no new cases after day 1.

What it means

Symptom screening alone missed many infections, and testing once would have missed more. Starting serial testing of close contacts as soon as a case is found, especially where people share living space, could limit spread; some infections here probably went undetected for weeks. Screening is also harder than it sounds: no single symptom was reported by most patients, common ones such as headache might not prompt a test, and people in custody may have reasons to report illness or not to. Serial testing needs trained staff, laboratory capacity and fast results.

It matters beyond the walls. About 10 million people are admitted to jails each year, and about 55 percent of detainees return to their communities each week; staff live in local communities too. The authors recommended quarantine and symptom screening at intake, infection control with protective equipment or cloth face coverings for staff and detainees, monitoring staff and keeping sick staff home, and cohorting people by infection status. On June 13, 2020, CDC recommended testing all close contacts in such high-risk settings, including those without symptoms.

Limits

Testing began two to four weeks after the first case, so much spread had already happened; about a third of those who tested negative reported earlier symptoms and may have already recovered. Staff were not systematically tested. Symptoms may have been under-reported, overstating how many infections had none. And this was one facility.

Sources

Based on "Serial Laboratory Testing for SARS-CoV-2 Infection Among Incarcerated and Detained Persons in a Correctional and Detention Facility — Louisiana, April–May 2020," by Henry Njuguna, Megan Wallace and colleagues (CDC; Louisiana Department of Health), Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention; a work of the United States government in the public domain.