Is the CDC’s 10-day COVID-19 quarantine guideline sufficient?

Coronavirus disease (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), continues to spread around the world. To date, more than 112.5 million people have been infected, with more than 2.49 million deaths lost to COVID-19.

The United States is one of the countries hardest hit by the pandemic, with the number of infections reaching 28.34 million. Due to the impact of the pandemic, many countries have closed, schools have been closed, and e-learning has replaced the classroom.

In recent months, schools and universities have permitted face-to-face classes on condition that students undergo a 14-day quarantine period if exposed to a case of SARS-CoV-2.

CDC Directive

Recently, the United States Centers for Disease Control and Prevention (CDC) updated their guideline. Depending on the circumstances and local resources, the quarantine may end after day 10 without testing and if no symptoms have been reported.

Data indicate that the incubation period of SARS-CoV-2 infection is between four and five days after exposure in adults and between six and seven days after exposure in children. As a result, Alachua County, Florida implemented SARS-CoV-2 testing on day 9 and return to school on day 10 for students with contacts of confirmed COVOD-19 cases.

Researchers at the University of Florida and the Florida Department of Health assessed the positivity rates of tests for SARS-CoV-2 infection among student contacts. The team found that nine days was not enough to ensure the student did not contract the virus.

The study

To arrive at the results of the study, published in the journal JAMA Network, researchers sought informed consent from parents of 26,456 kindergarten to 12-year-olds^e classroom.

Of these students, 49% were enrolled in face-to-face classes, where they are required to take physical classes. The county health department provided reverse transcriptase polymerase chain reaction (RT-PCR) tests to students who returned from quarantine.

The health department has also carried out samples for symptomatic students and contact tracing for confirmed positive COVID-19 cases.

Student contacts of confirmed cases were quarantined and subjected to RT-CR testing on day 3 and day 9. In some cases, testing was delayed for 10 to 14 days. Students without symptoms and testing negative on days 9-14 could return to school the day after testing negative. If no test took place, a 14-day quarantine was required.

Students who returned to school after testing negative were monitored for symptoms of COVID-19 until day 14.

Study results

The results of the study showed that from August 1 to November 30, 2020, Alachua County’s positivity rate was 4.9%. During this period, 495 suspected cases of students were tested. Of these, 51.9% tested positive for COVID-19. For these confirmed cases, 2,189 contacts were quarantined and isolated.

Additionally, 143 contacts were tested on day 3, while 839 contacts were tested on days 9-14. Of the student contacts who were tested on day 3, 10.4 percent were positive for SARS-CoV- 2. During that time, 40 contacts tested positive for COVID-19 on days 9 to 14.

Of the 799 contacts of confirmed COVID-19 cases with a negative test result on days 9 to 14, only one student became symptomatic after returning to school and tested positive on day 14, after testing negative at day 9. However, the virus isolated from the student is genetically distinct from the virus collected from the cases of COVID-19 to which the student has been exposed.

The researchers concluded that if students had returned to school before the 14th day without testing on or after day 9, about 8.2% of high school contacts would have returned to school with COVID-19.

The results of the study should be taken into account when evaluating the CDC’s recommendation for a 10-day quarantine without testing or a 7-day quarantine with testing.

However, the team also found no evidence that returning to school earlier with a negative test result was linked to subsequent symptomatic illness.

Since the duration of the quarantine for close contacts is still unclear, observing infection control measures is still crucial. These include washing your hands regularly, practicing social distancing, wearing masks and avoiding crowded places.