Longitudinal Wastewater-Based Surveillance for SARS-CoV-2 in High-Density Student Dormitories in Singapore

Environmental surveillance of wastewater from student dormitories was carried out over an academic year at a university campus in Singapore. From August 2021 to May 2022, SARS-CoV-2 RNA concentrations were quantified from concentrated 24-h composite wastewater samples collected twice weekly at 45 locations with sewer sheds serving between 400 and 1200 students. Two pilot studies using proxies for viral loading within the sanitary network were performed to determine the composite timings of the study. During the surveillance period, SARS-CoV-2 trends in campus wastewater levels closely resembled Singapore's combined national wastewater levels and clinical COVID-19 cases. In the examined sewer sheds, larger student populations significantly increased both the odds and duration of detecting SARS-CoV-2 RNA (p-value < 0.001 for both measures). However, the type of building corridor did not have a statistically significant impact on either the duration of detection (p-value = 0.716) or the odds of detecting the virus (p-value = 0.067). This study exemplifies the use of a decentralized and high-resolution surveillance system for the twice-weekly detection of viral shedding in high-density living conditions to support public health decisions and management.