June 11, 2020

CDC: Quarantine, Distancing Among Actions That Limited COVID-19 Transmission at Basic Training

A U.S. Air Force base in Texas significantly limited transmission of COVID-19 among cadets during basic training through nonpharmaceutical interventions such as quarantine and social distancing, according to a report from CDC released June 5. The report credits the interventions, implemented over a seven-week period from March 1 through April 18, with limiting the number of COVID-19 cases at Joint Base San Antonio-Lackland to five out of a population of nearly 10,600 cadets for a rate of 47 per 100,000 at a time when the overall rate of COVID-19 infections in the U.S. was 220 per 100,000.

Other interventions included early screening of trainees, rapid isolation of cadets with suspected cases, and monitored reentry into training for cadets who had tested positive for COVID-19 but who were no longer exhibiting symptoms.

The training for incoming cadets includes classroom lectures, small group activities, and field exercises. Cadets are grouped into cohorts of 50 who live in communal quarters and train as a group.

Symptomatic trainees underwent nasopharyngeal swabs, which were analyzed by polymerase chain reaction testing at a laboratory on base. Cadets who tested positive were isolated and were not permitted to return to training until at least seven days after symptom onset and at least three days without fever.

The Lackland base instituted travel restrictions and limited access to essential personnel, even for graduation ceremonies, which normally attract many visitors. When the first positive case in a trainee was confirmed on March 23, the base limited potential exposure by shortening the training schedule from eight and a half weeks to seven. Universal use of cloth facemasks was required beginning on April 6, and the base stopped accepting recruits from areas with high community transmission of SARS-CoV-2, the virus that causes COVID-19.

“Factors contributing to lack of transmission likely included early implementation of mitigation strategies before the first case occurred, mobilization of nonmedical personnel to assist in symptom screening, and flexibility of the military training staff to adjustments in programs and schedules,” according to the report. The Lackland base had previously housed symptomatic passengers from cruise ships and therefore already had infrastructure in place for infected cadets.

The report acknowledges that the highly structured nature of the military base likely contributed to the success of the interventions, and that these conditions may not be reproducible in other settings. It is also possible that asymptomatic transmission occurred that would not have been identified by the screening procedures, which relied on assessing symptoms.