Wastewater Surveillance of US Coast Guard Installations and Seagoing Military Vessels to Mitigate the Risk of COVID-19 Outbreaks, March 2021-August 2022

Abstract

Objectives: Military training centers and seagoing vessels are often environments at high risk for the spread of COVID-19 and other contagious diseases, because military trainees and personnel arrive after traveling from many parts of the country and live in congregate settings. We examined whether levels of SARS-CoV-2 genetic material in wastewater correlated with SARS-CoV-2 infections among military personnel living in communal barracks and vessels at US Coast Guard training centers in the United States.

Methods: The Coast Guard developed and established 3 laboratories with wastewater testing capability at Coast Guard training centers from March 2021 through August 2022. We analyzed wastewater from barracks housing trainees and from 4 Coast Guard vessels for the presence of SARS-CoV-2 genes N and E and quantified the results relative to levels of a fecal indicator virus, pepper mild mottle virus. We compared quantified data with the timing of medically diagnosed COVID-19 infection among (1) military personnel who had presented with symptoms or had been discovered through contact tracing and had medical tests and (2) military personnel who had been discovered through routine surveillance by positive SARS-CoV-2 antigen or polymerase chain reaction test results.

Results: Levels of viral genes in wastewater at Coast Guard locations were best correlated with diagnosed COVID-19 cases when wastewater testing was performed twice weekly with passive samplers deployed for the entire week; such testing detected ≥1 COVID-19 case 69.8% of the time and ≥3 cases 88.3% of the time. Wastewater assessment in vessels did not continue because of logistical constraints.

Conclusion: Wastewater testing is an effective tool for measuring the presence and patterns of SARS-CoV-2 infections among military populations. Success with wastewater testing for SARS-CoV-2 infections suggests that other diseases may be assessed with similar approaches.

Keywords: SARS-CoV-2; communicable diseases; military; occupational health; public health practice; testing; wastewater; water; workforce.

Figure 1.

SARS-CoV-2 levels relative to a fecal biomarker from samples collected at 2 untreated wastewater collection points (A and B) and diagnosed COVID-19 cases among military trainees at US Coast Guard training center A, March 9, 2021 (day 1), through August 15, 2022 (day 525). Training center A consisted of a single barracks, and wastewater samples were collected from 2 distinct portions of the same building for 525 days. Symbols show the presence of SARS-CoV-2 RNA N and E as detected by primer pairs (N1, E, N2) in the wastewater relative to the human fecal matter indicator pepper mild mottle virus (PMMoV). Primers N1 and E were used throughout, and N2 primers were added on day 409. Cases indicate military trainees with clinically diagnosed COVID-19 for the entire barracks; diagnosed cases were not separated between the sampling locations because of freedom of choice of restroom facilities by military trainees in the barracks. Wastewater sampling was temporarily halted during winter break and near day 335 because of a weather-related event preventing wastewater access. Abbreviations: Δ, Delta; Ο, Omicron.

Figure 2.

SARS-CoV-2 levels relative to a fecal biomarker from samples collected at 3 barracks (A-C) and diagnosed COVID-19 cases among military trainees at US Coast Guard training center B, June 21, 2021 (day 1), through September 14, 2022 (day 451). Each barracks had 2 sampling sites, East/West or North/South as indicated. Symbols show the presence of SARS-CoV-2 RNA detected by the indicated polymerase chain reaction primers (primer set N1, primer set E) in the wastewater relative to the human fecal matter indicator pepper mild mottle virus (PMMoV). Cases indicate people with clinically diagnosed COVID-19; such people were moved to an isolation building with a separate watershed. After initial SARS-CoV-2 antigen testing of trainees at the time of arrival, subsequent antigen tests were not routinely performed.

Figure 3.

SARS-CoV-2 levels relative to a fecal biomarker from samples collected at 3 separate barracks (A-C) and diagnosed COVID-19 cases among military trainees at US Coast Guard training center C, March 10, 2022 (day 1), through September 9, 2022 (day 183). Each building had 1 sampling site. Symbols show the presence of SARS-CoV-2 RNA detected by the indicated polymerase chain reaction primers (N1, E) in the wastewater relative to the human fecal matter indicator pepper mild mottle virus (PMMoV). Cases indicate people with clinically diagnosed COVID-19; such people were moved to an isolation building with a separate watershed. After initial SARS-CoV-2 antigen testing of trainees at the time of arrival, subsequent antigen tests were not routinely performed.