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Invited Commentary
Infectious Diseases
February 25, 2021

Controlling COVID-19 Spread in a Confined, High-Risk Population

Author Affiliations
  • 1Division of Infectious Diseases, Duke Global Health Institute, Durham, North Carolina
  • 2Duke University School of Medicine, Durham, North Carolina
JAMA Netw Open. 2021;4(2):e210234. doi:10.1001/jamanetworkopen.2021.0234

Marcus et al1 report on an encouraging coronavirus disease 2019 (COVID-19) control success story that public health officials serving similar high-risk populations may wish to emulate. From May 11 to August 24, 2020, 263 consecutive cohorts (30-50 persons each) of healthy young adults arrived at US Air Force Joint Base San Antonio–Lackland for recruit training. The trainees were screened twice during a 14-day quarantine period and closely monitored for COVID-19 infections. The multifaceted control plan was associated with a reduction in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission among the 10 613 trainees, and the authors used the complex surveillance data to identify some unique findings that might have been missed in studying smaller populations. The authors found that patients with more symptoms and lower SARS-CoV-2–positive cycle threshold assay values were associated with more viral transmission among their peers. The authors found that the multiple COVID-19 interventions at Joint Base San Antonio–Lackland worked well, and there was sparse evidence of asymptomatic superspreaders. This successful control program, which took place in such a historically high-risk setting (ie, a military training camp), may be a useful guide for public health officials working to halt transmission in confined settings.

Military training camps have historically been associated with respiratory epidemics, both bacterial and viral.2 Every week, trainees arrive from diverse geographical areas, and some may be infected with or carrying respiratory pathogens. The young men and women are assigned to training groups and share the same living quarters, bathrooms, classrooms, field activities, and transportation but often mix with other cohorts in shared areas such as dining halls and medical clinics. They are stressed physically, emotionally, and mentally as part of their military service orientation. Such stress is thought to increase their susceptibility to infectious diseases. So great is the risk of respiratory pathogen transmission that military training camps have often been the subject of respiratory pathogen research. Military trainees are among the first to have been prescribed novel interventions, such as long-acting penicillin injections,3 oral azithromycin prophylaxis,4 and an entire battery of vaccines.2 In these settings, it is almost impossible for trainees who are susceptible to avoid infection from an endemic pathogen. For instance, in a 2006 report of adenovirus infections, Russell et al5 found adenovirus was ubiquitous in a US military training camp, documenting many infections with an end-of-training adenovirus type 4 seroprevalence of 97% (243 of 251).

Marcus et al1 are to be commended for the detail they have recorded regarding the COVID-19 control plan in the current article and their previous report.6 In addition to the SARS-CoV-2 screenings at 0 and 14 days during the initial 2-week quarantine, trainees and staff practiced universal masking and social distancing. Access to the basic training areas was also restricted. After training began, trainees diagnosed with COVID-19 were isolated for 10 days regardless of symptoms and did not return to training until they had been afebrile for 24 hours. Training cohorts with an outbreak involving more than 30% of group members triggered additional mass screening of the entire cohort for the virus.

While the plan did not entirely stop disease transmission in the camp, it was associated with a lower number of infections than would be expected. Overall, 129 of the 263 cohorts (49%) had at least 1 COVID-19 case detected. Among the 403 total COVID-19 cases detected, most (260 [65%]) were detected during the 14-day quarantine and with only 143 (35%) detected later in training. This 1.3% SARS-CoV-2 infection rate (143 cases were detected after arrival among 10 613 trainees) during the 9 weeks (2 weeks of quarantine plus 7 weeks of recruit training) is in contrast to the experience of the USS Theodore Roosevelt, where 1331 of 4779 crew members (27.9%) developed suspected or confirmed COVID-19 during a 5-week period.7

The authors reported a vulnerability in the control plan, noting the importance of maintaining nonpharmaceutical interventions among all camp personnel. While recruit trainees could not leave the camp, other camp personnel could visit the surrounding community, which could cause new viral incursions among the trainees.

Although intensive and likely expensive in both medical services and costs, the Joint Base San Antonio–Lackland COVID-19 control plan could be used as a model for other high-risk, largely confined populations, such as those residing in long-term health care settings, nursing homes, cruise ships, prisons, colleges, and military training camps.

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Article Information

Published: February 25, 2021. doi:10.1001/jamanetworkopen.2021.0234

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2021 Gray GC. JAMA Network Open.

Corresponding Author: Gregory C. Gray, MD, MPH, Duke University School of Medicine, DUMC Box 102359, Durham, NC 27710 (

Conflict of Interest Disclosures: None reported.

Marcus  JE, Frankel  DN, Pawlak  MT,  et al.  Risk factors associated with COVID-19 transmission among US Air Force trainees in a congregant setting.   JAMA Netw Open. 2021;4(2):e210202. doi:10.1001/jamanetworkopen.2021.0202Google Scholar
Sanchez  JL, Cooper  MJ, Myers  CA,  et al.  Respiratory infections in the US military: recent experience and control.   Clin Microbiol Rev. 2015;28(3):743-800. doi:10.1128/CMR.00039-14PubMedGoogle ScholarCrossref
Gunzenhauser  JD, Brundage  JF, McNeil  JG, Miller  RN.  Broad and persistent effects of benzathine penicillin G in the prevention of febrile, acute respiratory disease.   J Infect Dis. 1992;166(2):365-373. doi:10.1093/infdis/166.2.365PubMedGoogle ScholarCrossref
Gray  GC, McPhate  DC, Leinonen  M,  et al.  Weekly oral azithromycin as prophylaxis for agents causing acute respiratory disease.   Clin Infect Dis. 1998;26(1):103-110. doi:10.1086/516275PubMedGoogle ScholarCrossref
Russell  KL, Broderick  MP, Franklin  SE,  et al.  Transmission dynamics and prospective environmental sampling of adenovirus in a military recruit setting.   J Infect Dis. 2006;194(7):877-885. doi:10.1086/507426PubMedGoogle ScholarCrossref
Marcus  JE, Frankel  DN, Pawlak  MT,  et al.  COVID-19 monitoring and response among US Air Force basic military trainees: Texas, March-April 2020.   Morb Mortal Wkly Rep. 2020;69(22):685-688. doi:10.15585/mmwr.mm6922e2PubMedGoogle ScholarCrossref
Payne  DC, Smith-Jeffcoat  SE, Nowak  G,  et al; CDC COVID-19 Surge Laboratory Group.  SARS-CoV-2 infections and serologic responses from a sample of US Navy service members: USS Theodore Roosevelt, April 2020.   Morb Mortal Wkly Rep. 2020;69(23):714-721. doi:10.15585/mmwr.mm6923e4PubMedGoogle ScholarCrossref
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