Military housing, whether in barracks or on an aircraft carrier, are close quarters that may facilitate transmission of SARS-CoV-2. Following are two summaries related to transmission in close quarters.
A. An outbreak of COVID-19 on an aircraft carrier.external icon Kasper et al. NEJM (November 11, 2020).
- 1,271 (27%) of 4,779 previously healthy navy crew members (mean age = 27) of an aircraft carrier became infected with SARS-CoV-2 (Figure).
- The first three cases presented after 13 days at sea.
- Four days later, the carrier docked in Guam and all crew were quarantined in separate hotel rooms.
- 77% (978/1,271) of crewmembers with confirmed COVID-19 were asymptomatic at the time of initial test and only about half (55%) later developed symptoms; overall, 572 (45%) of confirmed infections remained asymptomatic.
- 23 crew were hospitalized, four in the ICU, and one death occurred.
Methods: Retrospective review of transmission of SARS-CoV-2 among 4,779 crew of an aircraft carrier between March 11 and May 18, 2020. All crew who tested positive by RT-PCR were placed in isolation and underwent symptom monitoring twice a day. Limitations: Contact tracing did not include other potential contacts.
Note: Adapted from Kasper et al. COVID-19 cases among aircraft carrier crew between March and May 2020. COD, carrier onboard deliveries of personnel, supplies and mail. From NEJM, Kasper et al., An outbreak of COVID-19 on an aircraft carrier, Copyright © 2020 Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.
B. SARS-CoV-2 transmission among marine recruits during quarantineexternal icon. Letizia et al. NEJM (November 11, 2020).
- There were 77 infections (2.3%) detected among 3,402 recruits.
- 16 recruits were SARS-CoV-2-positive on arrival to the closed campus and 15 were asymptomatic.
- 55 recruits had a positive test by day 14 and of these, 46 were asymptomatic.
- 24 (31%) of the 77 infected recruits had an infected roommate.
- No infections were detected by daily symptom monitoring.
- Genotyping identified six clusters indicating local transmission.
Methods: A study in Marine recruits who self-quarantined 2 weeks at home and then were under supervised quarantine (double occupancy sleeping rooms, shared bathrooms and dining halls) at a closed campus for another 2 weeks between May 15 and July 14, 2020. While at the closed campus, they were tested by RT-PCR on days 0-2, 7, and 14. Phylogenic analysis of viral genomes were conducted to assess transmission routes. Limitations: On-campus quarantine was done with 2 persons per room and interactions were not closely tracked; 1,554 (45.7%) recruits were retested only on day 14.
Implications from 2 studies Kasper et al. & Letizia et al.: In close quarters, rapid extensive transmission of SARS-CoV-2 may occur. To protect service members, Michaelexternal icon, N. suggests a mandatory 14-day quarantine prior to confinement in close quarters, but Letizia et al.external icon suggest that even two weeks of prior self-quarantine plus two-weeks on-base quarantine was not adequate. These data provide evidence of the need to test asymptomatic individuals, particularly when dealing with young, healthy individuals, especially in settings with close quarters.