Perceptions and responses to COVID-19 through wastewater surveillance information and online search behavior: A randomized controlled trial (preprint)

Wastewater surveillance is anticipated to be a representative and timely method to assess infectious disease status; however, its influence on public perception and behavior remains unclear. Therefore, in this study, we used a randomized controlled trial to analyze the influence of wastewater surveillance-based information on understanding of, interest in, relief regarding, preventive behavioral intention against, and subsequent online search behavior related to coronavirus disease 2019 (COVID-19). Valid responses were obtained from 1,000 individuals in both control and intervention groups from Yahoo crowdsourcing users aged [≥]18 years in Japan. This survey was conducted from August 4 to August 7, 2023, just before the common Japanese tradition of returning to hometowns. The questionnaire not only collected personal attributes but also gauged responses to COVID-19 information. This information highlighted the early detection capabilities and representativeness of wastewater surveillance compared with sentinel surveillance at medical institutions. At one-week post-survey, we obtained the survey participants' online search history for key words such as "bullet train," "highway," "airplane," and "wastewater." The findings showed no significant differences between the two groups in terms of COVID-19 interest or preventive behavior before information provision, verifying the effectiveness of participant randomization. Wastewater surveillance-based information did not notably elevate understanding or specific intentions regarding COVID-19, such as wearing masks and receiving vaccination. However, it significantly increased interest in, relief concerning the infection status, and general preventive behavioral intentions. Heightened interest and general preventive intentions did not depend on prior interest or behavior. However, those who previously engaged in preventive behavior or who were less interested in COVID-19 exhibited more relief after exposure to wastewater surveillance-based information. Furthermore, this information could slightly influence online searches related to return travel modes, such as highways. In conclusion, information from wastewater surveillance effectively shapes individual perceptions of and responses to infections.

Age-dependent association between SARS-CoV-2 cases reported by passive surveillance and viral load in wastewater (preprint)

The true number of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is difficult to estimate using a case-reporting system (i.e., passive surveillance) alone because of asymptomatic infection. While wastewater-based epidemiology has been implemented as an alternative/additional monitoring tool to reduce reporting bias, the relationship between passive and wastewater surveillance data has yet to be explicitly examined. Since there is strong age dependency in the symptomatic ratio of SARS-CoV-2 infections, this study aimed to estimate i) an age-dependent association between the number of reported cases and the viral load in wastewater and ii) the time lag between those time series. The viral load in wastewater was modeled as a combination of contributions from different age groups' virus shedding, incorporating the delay, and fitted with daily case count data collected from the Massachusetts Department of Public Health and SARS-CoV-2 RNA concentrations in wastewater collected by the Massachusetts Water Resources Authority. The estimated lag between the time series of viral loads in wastewater and of reported cases was 10.8 days (95% confidence interval =[10.2, 11.6]) for wastewater treatment plant's northern area and 8.8 days [8.4, 9.1] for southern area. The estimated contribution rate of a reported case to the viral load in wastewater in the 0-19 yr age group was 0.38 [0.35, 0.41] for northern area and 0.40 [0.37, 0.43] for southern area, that in the 80+ yr age group was 0.67 [0.65, 0.69] for northern area and 0.51 [0.49, 0.52] for southern area. The estimated lag between those time series suggested the predictability of reported cases ten days later using viral loads in wastewater. The contribution of a reported case in passive surveillance to the viral load in wastewater differed by age, suggesting a large variation in viral shedding kinetics among age groups.

Minimizing Errors in RT-PCR Detection and Quantification of SARS-CoV-2 RNA for Wastewater Surveillance (preprint)

Wastewater surveillance for pathogens using the reverse transcription-polymerase chain reaction (RT-PCR) is an effective, resource-efficient tool for gathering additional community-level public health information, including the incidence and/or prevalence and trends of coronavirus disease-19 (COVID-19). Surveillance of SARS-CoV-2 in wastewater may provide an early-warning signal of COVID-19 infections in a community. The capacity of the world’s environmental microbiology and virology laboratories for SARS-CoV-2 RNA characterization in wastewater is rapidly increasing. However, there are no standardized protocols nor harmonized quality assurance and quality control (QA/QC) procedures for SARS-CoV-2 wastewater surveillance. This paper is a technical review of factors that can lead to false-positive and -negative errors in the surveillance of SARS-CoV-2, culminating in recommendations and strategies that can be implemented to identify and mitigate these errors. Recommendations include, stringent QA/QC measures, representative sampling approaches, effective virus concentration and efficient RNA extraction, amplification inhibition assessment, inclusion of sample processing controls, and considerations for RT-PCR assay selection and data interpretation. Clear data interpretation guidelines (e.g., determination of positive and negative samples) are critical, particularly during a low incidence of SARS-CoV-2 in wastewater. Corrective and confirmatory actions must be in place for inconclusive and/or potentially significant results (e.g., initial onset or reemergence of COVID-19 in a community). It will also be prudent to perform inter-laboratory comparisons to ensure results are reliable and interpretable for ongoing and retrospective analyses. The strategies that are recommended in this review aim to improve SARS-CoV-2 characterization for wastewater surveillance applications. A silver lining of the COVID-19 pandemic is that the efficacy of wastewater surveillance was demonstrated during this global crisis. In the future, wastewater will play an important role in the surveillance of a range of other communicable diseases.

Duration of SARS-CoV-2 viral shedding in faeces as a parameter for wastewater-based epidemiology: Re-analysis of patient data using a shedding dynamics model (preprint)

BackgroundWastewater-based epidemiology (WBE) is one of the most promising approaches to effectively monitor the spread of the novel coronavirus disease 2019 (COVID-19). The virus concentration in faeces and its temporal variations are essential information for WBE. While some clinical studies have reported severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) concentrations in faeces, the value varies amongst patients and changes over time. AimThe present study aimed to examine how the temporal variations in the concentration of virus in faeces affect the monitoring of disease incidence. We re-analysed the experimental findings of clinical studies to estimate the duration of virus shedding and the faecal virus concentration. MethodAvailable experimental data as of 23 October, 2020 were collected and patient data reported in Germany were included for further analysis. The viral shedding kinetics was modelled, and the dynamic model was fitted to the collected experimental data by a Bayesian framework. Using samples of posterior distributions, the duration of viral shedding and the concentration of virus copies in faeces over time were computed. ResultsWe estimated the median concentration of SARS-CoV-2 in faeces as 2.6 (95% Credible Interval (CrI): 0.22-4.8) log copies per gram (g) of faeces over the shedding period, and our model implied that the duration of viral shedding was 23.2 days (95% CrI: 19.5-31.5), given the current standard quantification limit (Ct = 40). With simulated incidences, our results also indicated that a one-week delay between symptom onset and wastewater sampling increased the estimation of incidence by 13.5%. ConclusionsOur results demonstrated that the temporal variation in virus concentration in faeces affects microbial monitoring systems such as WBE. The present study also implied the need for adjusting the estimates of virus concentration in faeces by incorporating the kinetics of unobserved concentrations. The method used in this study is easily implemented in further simulations; therefore, the results of this study might contribute to enhancing disease surveillance and risk assessments that require quantities of virus to be excreted into the environment.

First environmental surveillance for the presence of SARS-CoV-2 RNA in wastewater and river water in Japan (preprint)

Wastewater-based epidemiology is a powerful tool to understand the actual incidence of coronavirus disease 2019 (COVID-19) in a community because severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, can be shed in the feces of infected individuals regardless of their symptoms. The present study aimed to assess the presence of SARS-CoV-2 RNA in wastewater and river water in Yamanashi Prefecture, Japan, using four quantitative and two nested PCR assays. Influent and secondary-treated (before chlorination) wastewater samples and river water samples were collected five times from a wastewater treatment plant and three times from a river, respectively, between March 17 and May 7, 2020. The wastewater and river water samples (200-5,000 mL) were processed by using two different methods: the electronegative membrane-vortex (EMV) method and the membrane adsorption-direct RNA extraction method. Based on the observed concentrations of indigenous pepper mild mottle virus RNA, the EMV method was found superior to the membrane adsorption-direct RNA extraction method. SARS-CoV-2 RNA was successfully detected in one of five secondary-treated wastewater samples with a concentration of 2.4 x 103 copies/L by N_Sarbeco qPCR assay following the EMV method, whereas all the influent samples were tested negative for SARS-CoV-2 RNA. This result could be attributed to higher limit of detection for influent (4.0 x 103-8.2 x 104 copies/L) with a lower filtration volume (200 mL) compared to that for secondary-treated wastewater (1.4 x 102-2.5 x 103 copies/L) with a higher filtration volume of 5,000 mL. None of the river water samples tested positive for SARS-CoV-2 RNA. Comparison with the reported COVID-19 cases in Yamanashi Prefecture showed that SARS-CoV-2 RNA was detected in the secondary-treated wastewater sample when the cases peaked in the community. This is the first study reporting the detection of SARS-CoV-2 RNA in wastewater in Japan.