Environmental SARS-CoV-2 surveillance in Singapore built environment

The recent outbreak of the novel coronavirus SARS-CoV-2 has resulted in a large number of infections and significant mortality in more than 100 countries globally. Spreading of SARS-CoV-2 infections is currently monitored by testing individuals with respiratory and other symptoms on a case-by-case basis, often multiple times. This results in substantial costs and efforts and is not suited in instances where large groups of people in mass gatherings have to be assessed on a short time scale. We therefore propose to establish the limits of detection for SARS-CoV-2 nucleic acids, collected by high volumetric flowrate air samplers in indoor settings. The approach is based on an ultra-low biomass analysis pipeline that was established within an MOE Tier 3 programme on the sources, function and ecology of urban air microbiomes. Using a sampling regime within NUH isolation wards, the team aims to demonstrate in principle that detection of SARS-CoV-2 in air samples is possible. Our ongoing collaborative efforts between NUS, NUH and NEA during the COVID-19 outbreak have established experimental procedures in NUH isolation wards that can now serve as test beds for the proposed population-scale testing. Using the airflow in NUH isolation rooms for pilot studies, we will sample airborne biomass both in-room and the exhaust air, thereby testing the feasibility of RT-PCR detection of viral nucleic acids in large volumes of air. The knowledge gained from these pilot studies can then be extended to other settings in the Singapore built environment. This potentially will enable continuous monitoring of schools, religious gathering places, shopping centres, airports, and various forms of mass transport. The development of air sample-based environmental surveys can proceed instantly using an experienced team of investigators and an existing fleet of 47 air samplers at SCELSE and 20 units at NEA.