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Faecal shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its subsequent detection in wastewater turned the spotlight onto wastewater-based epidemiology (WBE) for monitoring the coronavirus-disease 2019 (COVID-19) pandemic. WBE for SARS-CoV-2 has been deployed in 70 countries, providing insights into disease prevalence, forecasting and the spatiotemporal tracking and emergence of SARS-CoV-2 variants. Wastewater, however, is a complex sample matrix containing numerous reverse transcription quantitative PCR (RT-qPCR) inhibitors whose concentration and diversity are influenced by factors including population size, surrounding industry and agriculture and climate. Such differences in the RT-qPCR inhibitor profile are likely to impact the quality of data produced by WBE and potentially produce erroneous results.To help determine the possible impact of RT-qPCR assay on data quality, two assays employed by different laboratories within the UK's SARS-CoV-2 wastewater monitoring programme were assessed in the Cefas laboratory in Weymouth, UK. The assays were based on Fast Virus (FV) and qScript (qS) chemistries using the same primers and probes, but at different concentrations and under different cycling conditions. Bovine serum albumin and MgSO4 were also added to the FV assay reaction mixture. Two-hundred and eighty-six samples were analysed, and an external control RNA (EC RNA)-based method was used to measure RT-qPCR inhibition. Compared with qS, FV showed a 40.5% reduction in mean inhibition and a 57.0% reduction in inter-sample inhibition variability. A 4.1-fold increase in SARS-CoV-2 quantification was seen for FV relative to qS; partially due (1.5-fold) to differences in reverse transcription efficiency and the use of a dsDNA standard. Analytical variability was reduced by 51.2% using FV while qS increased the number of SARS-CoV-2 negative samples by 2.6-fold. This study indicates the importance of thorough method optimisation for RT-qPCR-based WBE which should be performed using a selection of samples which are representative of the physiochemical properties of wastewater. Furthermore, RT-qPCR inhibition, analytical variability and reverse transcription efficiency should be key considerations during assay optimisation. A standardised framework for the optimisation and validation of WBE procedures should be formed including concessions for emergency response situations that would allow flexibility in the process to address the difficult balance between the urgency of providing data and the availability of resources.
Subject(s)
COVID-19 , Reverse Transcription , Humans , RNA, Viral , Wastewater , SARS-CoV-2 , Polymerase Chain ReactionABSTRACT
Coronavirus is one of the main pathogens that primarily targets the human respiratory system. There are several ways to transmit this virus, such as direct contact or droplets spread by coughing or sneezing, and direct contact with fomites and surfaces is another way. This cross-sectional study was conducted in Shiraz, southern Iran, in 2021. 5 locations, including 3 hospitals and 2 dormitories, were selected for the survey. The cockroaches were collected from selected locations and transferred to the Laboratory of Medical Entomology at Shiraz University of Medical Sciences. All specimens were identified morphologically. The external and gastrointestinal washouts of collected samples with sterile phosphate-buffered saline separately were used for molecular analysis. An RT-qPCR assay, which suggests the possible insectborne transmission, was used. External and gastrointestinal washout of B. germanica from Dastgheyb Dormitory and P. americana from Ali-Asghar Hospital were positive for contamination with the SARS-CoV-2. Cockroaches spread the virus in the environment and contaminate human food and various surfaces of buildings. Their role will be more important in crowded places such as hotels, lodging houses, restaurants, and hospitals; vector control programs should be carried out with more accuracy in such places.
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Certain viral pathogens can be shed into the human breast milk and cause infections in the infant upon breastfeeding. Thus, it is important to clarify whether viral RNA as well as infectious virus can be found in breast milk. The complexity of this body fluid poses several challenges for viral RNA isolation and detection of infectious virus. We here provide a protocol that allowed the identification of SARS-CoV-2 RNA in breast milk and the isolation of infectious virus after the virus has been artificially spiked into milk samples.
Subject(s)
COVID-19 , SARS-CoV-2 , Infant , Female , Humans , Milk, Human , RNA, Viral , Breast FeedingABSTRACT
Previous data have suggested an antiviral effect of teriflunomide, including against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the agent underlying the ongoing COVID-19 pandemic. We undertook an in vitro investigation to evaluate the inhibitory activity of teriflunomide against SARS-CoV-2 in a cell-based assay. Teriflunomide was added to Vero (kidney epithelial) cells that had been infected with SARS-CoV-2. A nucleocapsid immunofluorescence assay was performed to examine viral inhibition with teriflunomide and any potential cytotoxic effect. The 50% effective concentration (EC(50)) for teriflunomide against SARS-CoV-2 was 15.22 μM. No cytotoxicity was evident for teriflunomide in the Vero cells (i.e., the 50% cytotoxic concentration [CC(50)] was greater than the highest test concentration of 100 μM). The data were supported by additional experiments using other coronaviruses and human cell lines. In the SARS-CoV-2-infected Vero cells, the prodrug leflunomide had an EC(50) of 16.49 μM and a CC(50) of 54.80 μM. Our finding of teriflunomide-mediated inhibition of SARS-CoV-2 infection at double-digit micromolar potency adds to a growing body of evidence for a broad-ranging antiviral effect of teriflunomide.
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Mutations in the SARS-CoV-2 genome may negatively impact a diagnostic test, have no effect, or turn into an opportunity for rapid molecular screening of variants. Using an in-house FDA Emergency Used Authorized RT-qPCR-based COVID-19 diagnostic assay, we combined sequence surveillance of viral variants and computed PCR efficiencies for mismatched templates. We found no significant mismatches for the N, E, and S set of assay primers until the Omicron variant emerged in late November 2021. We found a single mismatch between the Omicron sequence and one of our assay's primers caused a >4 cycle delay during amplification without impacting overall assay performance. Starting in December 2021, clinical specimens received for COVID-19 diagnostic testing that generated a Cq delay greater than 4 cycles were sequenced and confirmed as Omicron. Clinical samples without a Cq delay were largely confirmed as the Delta variant. The primer-template mismatch was then used as a rapid surrogate marker for Omicron. Primers that correctly identified Omicron were designed and tested, which prepared us for the emergence of future variants with novel mismatches to our diagnostic assay's primers. Our experience demonstrates the importance of monitoring sequences, the need for predicting the impact of mismatches, their value as a surrogate marker, and the relevance of adapting one's molecular diagnostic test for evolving pathogens.
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There are a high number of COVID-19 cases per capita in the world that goes undetected including clinical diseases compatible with COVID-19. While the presence of the COVID-19 in untreated drinking water is possible, it is yet to be detected in the drinking-water supplies. COVID-19 viral fragments have been found in excrete, this call for wastewater monitoring and analysis (wastewater surveillance) of the potential health risk. This raises concern about the potential of the SARS-CoV-2 transmission via the water systems. The economic limits on the medical screening for the SARS-CoV-2 or COVID-19 worldwide are turning to wastewater-based epidemiology as great potential tools for assessing and management of the COVID-19 pandemic. Surveillance and tracking of the pathogens in the wastewater are key to the early warning system and public health strategy monitoring of the COVID-19. Currently, RT-qPCR assays is been developed for SARS-CoV-2 RNA specimen clinical testing and detection in the water system. Convectional wastewater treatment methods and disinfection are expected to eradicate the SAR-CoV-2. Chlorine, UV radiation, ozone, chloramine is been used to inactivate and disinfect the water treatment system against the SARS-CoV-2. Water management and design of the water infrastructure require major changes to accommodate climate change, water cycle, reimaging of digitalization, infrastructure and privacy protection. The water digital revolution, biosensors and nanoscale, contact tracing, knowledge management can accelerate with disruption of the COVID-19 outbreak (water-health-digital nexus).
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To identify false-positive SARS-CoV-2 test results caused by novel coronavirus inactivated vaccine contamination, a novel RT-qPCR targeting the ORF1ab and N genes of SARS-CoV-2 and Vero gene was developed. The amplification efficiency, precision, and lower limit of detection (LLOD) of the RT-qPCR assay were determined. A total of 346 clinical samples and 132 environmental samples were assessed, and the diagnostic performance was evaluated. The results showed that the amplification efficiency of the ORF1ab, N, and Vero genes was 95%, 97%, and 93%, respectively. The coefficients of variation of Ct values at a concentration of 3 × 104 copies/mL were lower than 5%. The LLOD for the ORF1ab, N, and Vero genes reached 8.0, 3.3, and 8.2 copies/reaction, respectively. For the 346 clinical samples, our RT-qPCR assay identified SARS-CoV-2-positive and SARS-CoV-2-negative samples with a sensitivity of 100.00% and a specificity of 99.30% and novel coronavirus inactivated vaccine-contaminated samples with a sensitivity of 100% and a specificity of 100%. For the environmental samples, our RT-qPCR assay identified novel coronavirus inactivated vaccine-contaminated samples with a sensitivity of 88.06% and a specificity of 95.38%. In conclusion, the RT-qPCR assay we established can be used to diagnose COVID-19 and, to a certain extent, false-positive results due to vaccine contamination.
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Accurate and rapid identification of COVID-19 is critical for effective patient treatment and disease outcomes, as well as the prevention of SARS-CoV-2 transmission. Rapid antigen tests (RATs) for identifying SARS-CoV-2 are simpler, faster and less expensive than molecular assays. Any new product to be considered a medical device is subject to evaluation and data analysis to verify the in vitro diagnostic ability to achieve its intended purpose. Clinical validation of such a test is a prerequisite before clinical application. This study was a clinical validation on adult Europeans of GenBody COVID-19 Ag, nasal and nasopharyngeal RATs. A set of 103 positive and 301 negative from nose and nasopharynx samples confirmed by RT-qPCR were examined. The tests were safe to use and showed 100% specificity in both specimens, and high sensitivity of 94.17% (95%CI 87.75% to 97.83%) and 97.09% (95%CI 91.72% to 99.4%), respectively. The parameters were significantly better for samples with higher virus loads (the highest for CT ≤ 25). The GenBody COVID-19 Ag RATs are inexpensive (compared to RT-qPCR), reliable and rapid with high sensitivity and specificity, making them suitable for diagnosis and timely isolation and treatment of COVID-19 patients, contributing to the better control of virus spread.
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We describe a case of a 24-year-old Brazilian woman previously vaccinated with CoronaVac and a booster dose of Pfizer-BioNTech, with mild-to-moderate COVID-19, with persistent viral shedding. We evaluated viral load, antibody dynamics for SARS-CoV-2 and performed genomic analysis to identify the viral variant. The female remained positive for 40 days following symptom onset (cycle quantification mean: 32.54 ± 2.29). The humoral response was characterized by absence of IgM for the viral spike protein, increased IgG for the viral spike (1800.60 to 19558.60 AU/mL) and for the nucleocapsid (from 0.03 to 8.9 index value) proteins, and high titers of neutralizing antibodies (>488.00 IU/mL). The variant identified was the sublineage BA. 5.1. of Omicron (B.1.1.529). Our results suggest that even though the female produced an antibody response against SARS-CoV-2, the persistent infection can be explained by antibody decline and/or the immune evasion by the Omicron variant, illustrating the need to revaccinate or update vaccines.
Subject(s)
COVID-19 Vaccines , COVID-19 , Female , Humans , Young Adult , Adult , COVID-19/prevention & control , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, ViralABSTRACT
PURPOSE: Real time reverse transcriptase polymerase chain reaction (RT-qPCR) is still considered a gold standard for the diagnosis of COVID-19. However, due to several limitations, use of RT-qPCR is limited in a resource poor setting like North East India. Rapid antigen detection testing kit has revolutionized the diagnosis and management of COVID-19 in India. However, conflicting reports exist regarding the efficacy of the kits for diagnosis of COVID-19. This study aims to highlight the performance of Standard Q COVID-19® Antigen detection kit (SD Biosensor) compared with RT-qPCR in the setup of North East India. METHODS: Nasopharyngeal and oropharyngeal swab samples were collected from consenting patients attending the flu clinic in the period from 1st July to December 31, 2020. Samples were transferred to Viral Research and Diagnostic Laboratory (VRDL) for RT-qPCR test. Antigen detection from the patient samples were undertaken using Standard Q ® COVID-19 antigen detection kit (SD Biosensor, Republic of Korea). Data were then analyzed for comparison between RT-qPCR and antigen kit results. RESULTS: During the study period, 189 samples were collected, out of which 119 were positive by RT-qPCR. Out of 119 positive samples, calculated sensitivity and specificity of the rapid antigen kit was 63% and 100% respectively. Sensitivity and diagnostic accuracy increases in symptomatic patients as compared to asymptomatic patients. Cohen's Kappa coefficient showed a moderate association (0.6) between the kit and RT-qPCR test. The kit performed optimally at a CT value of ≤32.5 for N gene with a predicted sensitivity of 77.3% and specificity of 93.3%. CONCLUSION: The study shows an overall acceptable sensitivity and specificity of the testing kit, with a better performance in symptomatic patients. The association of the kit result is moderate with the results obtained in RT-qPCR. In this study, the rapid antigen test kit performed optimally at N gene qRT PCR cut off value of ≤32.5.
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Introduction: The imminent risk of zoonoses of non-human malaria parasites is not far from reality in India, as has been observed in the case of Plasmodium knowlesi (Pk), and so is possible with P. cynomolgi (Pc), already reported from South East Asian countries. Therefore, a novel multiplex qPCR assay was developed and evaluated for detection of non-human malaria parasites- Pk and Pc in populations at risk. Methods: The qPCR primers were designed in-house with fluorescence labeled probes (HEX for Pk and FAM for Pc). DNA samples of Pk and Pc were used as templates and further the qPCR assay was evaluated in 250 symptomatic and asymptomatic suspected human blood samples from malaria endemic areas of North Eastern states of India. Results: The qPCR assay successfully amplified the target 18S rRNA gene segment from Pk and Pc and was highly specific for Pk and Pc parasites only, as no cross reactivity was observed with P. falciparum (Pf), P. vivax (Pv), P. malariae (Pm), and P. ovale (Po). Standard curves were generated to estimate the limit of detection (LOD) of Pk and Pc parasites DNA (0.00275 & 0.075 ng/µl, respectively). Due to COVID-19 pandemic situation during 2020-21, the sample accessibility was difficult, however, we managed to collect 250 samples. The samples were tested for Pf and Pv using conventional PCR- 14 Pf and 11 Pv infections were observed, but no Pk and Pc infections were detected. For Pk infections, previously reported conventional PCR was also performed, but no Pk infection was detected. Discussion: The multiplex qPCR assay was observed to be robust, quick, cost-effective and highly sensitive as compared to the currently available conventional PCR methods. Further validation of the multiplex qPCR assay in field setting is desirable, especially from the high-risk populations. We anticipate that the multiplex qPCR assay would prove to be a useful tool in mass screening and surveillance programs for detection of non-human malaria parasites toward the control and elimination of malaria from India by 2030.
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Parachlamydia acanthamoebae and Simkania negevensis, two Chlamydia-like bacteria, have been recently recognized as emerging human respiratory pathogens. The prevalence and frequency of these bacteria in the environment and among atypical pneumonia patients are still underestimated by classical cultures, immunohistochemistry and serology which are non-specific, long and tedious methods. This study aims to develop a new duplex probe-based q-PCR assay for the simultaneous detection and quantification of P. acanthamoebae and S. negevensis. The selected hydrolysis probes displayed no cross-reaction with the closely related Chlamydia or the other tested waterborne pathogens. The assay achieved a large dynamic range for quantification (from 5 × 106 to 5 DNA copies/reaction). Efficiencies of FAM and JOE label probes weren't affected when they were combined. They were close to 100%, indicating the linear amplification. The application of this diagnostic tool resulted in 9/47 (19%) and 4/47 (8.5%) positive water samples for P. acanthamoebae and S. negevensis, respectively. P. acanthamoebae was also covered from 2/78 (2.5%) respiratory specimens and only one case (1/200 = 0.5%) of P. acanthamoebae and SARS-CoV-2 co-infection was noticed. While S. negevensis wasn't detected in clinical samples, the developed duplex q-PCR was shown to be an accurate, highly sensitive, and robust diagnostic tool for the detection and quantification of P. acanthamoebae and S. negevensis.
Subject(s)
COVID-19 , Humans , SARS-CoV-2 , Polymerase Chain Reaction/methods , COVID-19 TestingABSTRACT
BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant of concern (VoC) Omicron (B.1.1.529) has rapidly spread around the world, presenting a new threat to global public human health. Due to the large number of mutations accumulated by SARS-CoV-2 Omicron, concerns have emerged over potentially reduced diagnostic accuracy of reverse-transcription polymerase chain reaction (RT-qPCR), the gold standard diagnostic test for diagnosing coronavirus disease 2019 (COVID-19). Thus, we aimed to assess the impact of the currently endemic Omicron sublineages BA.4 and BA.5 on the integrity and sensitivity of RT-qPCR assays used for coronavirus disease 2019 (COVID-19) diagnosis via in silico analysis. We employed whole genome sequencing data and evaluated the potential for false negatives or test failure due to mismatches between primers/probes and the Omicron VoC viral genome. METHODS: In silico sensitivity of 12 RT-qPCR tests (containing 30 primers and probe sets) developed for detection of SARS-CoV-2 reported by the World Health Organization (WHO) or available in the literature, was assessed for specifically detecting SARS-CoV-2 Omicron BA.4 and BA.5 sublineages, obtained after removing redundancy from publicly available genomes from National Center for Biotechnology Information (NCBI) and Global Initiative on Sharing Avian Influenza Data (GISAID) databases. Mismatches between amplicon regions of SARS-CoV-2 Omicron VoC and primers and probe sets were evaluated, and clustering analysis of corresponding amplicon sequences was carried out. RESULTS: From the 1164 representative SARS-CoV-2 Omicron VoC BA.4 sublineage genomes analyzed, a substitution in the first five nucleotides (C to T) of the amplicon's 3'-end was observed in all samples resulting in 0% sensitivity for assays HKUnivRdRp/Hel (mismatch in reverse primer) and CoremCharite N (mismatch in both forward and reverse primers). Due to a mismatch in the forward primer's 5'-end (3-nucleotide substitution, GGG to AAC), the sensitivity of the ChinaCDC N assay was at 0.69%. The 10 nucleotide mismatches in the reverse primer resulted in 0.09% sensitivity for Omicron sublineage BA.4 for Thai N assay. Of the 1926 BA.5 sublineage genomes, HKUnivRdRp/Hel assay also had 0% sensitivity. A sensitivity of 3.06% was observed for the ChinaCDC N assay because of a mismatch in the forward primer's 5'-end (3-nucleotide substitution, GGG to AAC). Similarly, due to the 10 nucleotide mismatches in the reverse primer, the Thai N assay's sensitivity was low at 0.21% for sublineage BA.5. Further, eight assays for BA.4 sublineage retained high sensitivity (more than 97%) and 9 assays for BA.5 sublineage retained more than 99% sensitivity. CONCLUSION: We observed four assays (HKUnivRdRp/Hel, ChinaCDC N, Thai N, CoremCharite N) that could potentially result in false negative results for SARS-CoV-2 Omicron VoCs BA.4 and BA.5 sublineages. Interestingly, CoremCharite N had 0% sensitivity for Omicron Voc BA.4 but 99.53% sensitivity for BA.5. In addition, 66.67% of the assays for BA.4 sublineage and 75% of the assays for BA.5 sublineage retained high sensitivity. Further, amplicon clustering and additional substitution analysis along with sensitivity analysis could be used for the modification and development of RT-qPCR assays for detecting SARS-CoV-2 Omicron VoC sublineages.
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Diagnostic accuracy of COVID-19 varies among different assays. In this study, the analytical performance of 1 rapid nucleic acid detection assay (Coyote assay) and 2 routine RT-qPCR assays (BioGerm assay and DaAn assay) was evaluated, using 1196 clinical samples. Disagreement in the results of 2 paired targets occurred in all 3 assays. The Coyote assay failed to detect 15 samples, and the DaAn assay failed to detect 5 samples. The Cohen's kappa coefficient was 0.970 between the BioGerm and DaAn assays, 0.907 between the Coyote and BioGerm assays, and 0.936 between the Coyote and DaAn assays. The positive percent agreement, and negative percent agreement of the Coyote assay were 84.04%, and 100%, respectively. Our study revealed that the results of the Coyote, BioGerm, and DaAn assays were highly consistent, which provided reference for the application of these assays for diagnosis of COVID-19.
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BACKGROUND: Coronavirus disease 2019 (COVID-19) is a modern infectious disease, first identified in December 2019 in Wuhan, China. The etiology is via severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in a pandemic manner. The study aimed to compare between RT-PCR and rapid anti-gene tests for COVID-19 with regard to sensitivity and specificity. METHODS: This is a cohort hospital-based study done during the period of July to September 2020. Both rapid anti-gene test kit (SARS-CoV-2) and RT-qPCR were used for the detection of COVID-19 in suspected cases. RESULTS: A total of 148 cases were tested using both the RT-qPCR and rapid test. Twenty-nine (19.6%) of these cases had positive results for RT-qPCR and 119 (80.4%) were negative, whereas 52 (35.1%) patients were positive to rapid anti-gene test and 96 (64.9%) of them negative. The sensitivity of the rapid test was 37.9%, the specificity was 65.5% and the accuracy was 64.44%. Rapid IgG test was positive in 47 (31.8) of cases. Although, rapid IgM test was positive in 18 (12.2%). The rapid IgG test was more sensitive than rapid IgM (Sensitivity 34.48% vs. 3.45%), but it was less specific than rapid IgM test (Specificity 68.91% vs. 85.71%). CONCLUSION: We cannot consider rapid anti-gene test alone as a diagnostic method for COVID-19. We should also conduct RT-PCR test and other investigations like imaging CT scan of chest to confirm the diagnosis. The rapid IgG test is more sensitive than rapid IgM, but it was less specific.
Subject(s)
COVID-19 , Humans , COVID-19/diagnosis , SARS-CoV-2 , COVID-19 Testing , Reverse Transcriptase Polymerase Chain Reaction , Clinical Laboratory Techniques/methods , Sensitivity and Specificity , Immunoglobulin G , Immunoglobulin MABSTRACT
Certain viral pathogens can be shed into the human breast milk and cause infections in the infant upon breastfeeding. Thus, it is important to clarify whether viral RNA as well as infectious virus can be found in breast milk. The complexity of this body fluid poses several challenges for viral RNA isolation and detection of infectious virus. We here provide a protocol that allowed the identification of SARS-CoV-2 RNA in breast milk and the isolation of infectious virus after the virus has been artificially spiked into milk samples.
Subject(s)
COVID-19 , SARS-CoV-2 , Infant , Female , Humans , Milk, Human , RNA, Viral , Breast FeedingABSTRACT
Wastewater-based SARS-CoV-2 surveillance enables unbiased and comprehensive monitoring of defined sewersheds. We performed real-time monitoring of hospital wastewater that differentiated Delta and Omicron variants within total SARS-CoV-2-RNA, enabling correlation to COVID-19 cases from three tertiary-care facilities with >2100 inpatient beds in Calgary, Canada. RNA was extracted from hospital wastewater between August/2021 and January/2022, and SARS-CoV-2 quantified using RT-qPCR. Assays targeting R203M and R203K/G204R established the proportional abundance of Delta and Omicron, respectively. Total and variant-specific SARS-CoV-2 in wastewater was compared to data for variant specific COVID-19 hospitalizations, hospital-acquired infections, and outbreaks. Ninety-six percent (188/196) of wastewater samples were SARS-CoV-2 positive. Total SARS-CoV-2 RNA levels in wastewater increased in tandem with total prevalent cases (Delta plus Omicron). Variant-specific assessments showed this increase to be mainly driven by Omicron. Hospital-acquired cases of COVID-19 were associated with large spikes in wastewater SARS-CoV-2 and levels were significantly increased during outbreaks relative to nonoutbreak periods for total SARS-CoV2, Delta and Omicron. SARS-CoV-2 in hospital wastewater was significantly higher during the Omicron-wave irrespective of outbreaks. Wastewater-based monitoring of SARS-CoV-2 and its variants represents a novel tool for passive COVID-19 infection surveillance, case identification, containment, and potentially to mitigate viral spread in hospitals.