Detection Of SARS-COV-2 Variants Of Concern In Wastewater Of Leuven, Belgium

Abstract

To investigate whether wastewater surveillance can be used as an early warning system to detect a rise in SARS-CoV-2 positive cases, and to follow the circulation of specific variants of concern (VOC) in particular geographical areas, wastewater samples were collected from local neighborhood sewers and from a large regional wastewater treatment plant (WWTP) in the area of Leuven, Belgium. In two residential sampling sites, a rise in viral SARS-CoV-2 copies in wastewater preceded the peaks in positive cases. In the WWTP, peaks in the wastewater viral load were seen simultaneous with the waves op positive cases caused by the original Wuhan SARS-CoV-2 strain, the Alpha variant and the Delta variant. For the Omicron BA.1 variant associated wave, the viral load in wastewater increased to a lesser degree, and much later than the increase in positive cases, which could be attributed to a lower level of fecal excretion, as measured in hospitalized patients. Circulation of SARS-CoV-2 VOCs (Alpha, Delta and Omicron) could be detected based on the presence of specific key mutations. The shift in variants was noticeable in the wastewater, with key mutations of two different variants being present simultaneously during the transition period.We found that wastewater based surveillance is a sensitive tool to monitor SARS-CoV-2 circulation levels and VOCs in larger regions. This can prove to be highly valuable in times of reducing testing capacity. Differences in excretion levels of various SARS-CoV-2 variants should however be taken into account when using wastewater surveillance to monitor SARS-CoV-2 circulation levels in the population.

Natural ventilation, low CO2 and air filtration are associated with reduced indoor air respiratory pathogens

“…During the COVID-19 pandemic, pathogen detection in sewage was scaled and provided important policy insights 29 . As environmental samples are not influenced by clinical test indications, tendency for testing or laboratory capacity, they can complement diagnostic tests and sentinel surveillance.…”

“…Sewage sampling can surveil the population of entire cities, but also has disadvantages. It is highly contaminated with environmental microorganisms, the relationship between respiratory and gastrointestinal shedding may be complex, and runoff times may be long and variable 29 . These make air sampling an interesting and complimentary alternative.…”

“…In addition to quantifying transmission risk, sampling and testing of indoor air for respiratory pathogen bioaerosols may become an important add-on to other monitoring practices such as clinical samples, sentinel surveillance and sewage monitoring 29,30 . QPCR on ambient air has long demonstrated its ability to detect pathogen presence, concentration, viability, and genotype 5,[30][31][32][33] .…”

Environmental circulation of adenovirus 40/41 and SARS-CoV-2 in the context of the emergence of acute hepatitis of unknown origin

“…Circulation of adenovirus 40/41 and SARS-CoV-2 in the general population in wastewater We retrospectively assessed the level of circulation of adenovirus and SARS-CoV-2 by performing AdV 40/41 and SARS-CoV-2 qPCR on 63 sequential wastewater samples collected between 06/12/2020 and 16/05/2022. These samples were taken at a sampling site allowing the surveillance of SARS-CoV-2 transmission in the entire city [8]. As presented in Figure 1, the circulation of SARS-CoV-2 peaked in April 2021 (Alpha wave) and December 2021 (Delta wave), and thereafter remained at a high level throughout the Omicron BA.1 (January 2022) and BA.2 (March 2022) waves of infection.…”

“…Wastewater samples were collected and concentrated. SARS-CoV-2 was detected as previously described in Bloemen et al 2022 [8].…”