SARS-CoV-2 wastewater concentration and linked longitudinal seroprevalence: a spatial analysis of strain mutation, post-COVID-19 vaccination effect, and hospitalization burden forecasting

Background Since early in the COVID-19 pandemic, SARS-CoV-2 wastewater concentration has been measured as a surrogate for community prevalence. However, our knowledge remains limited regarding wastewater concentration and effects of the COVID-19 vaccination on overall disease burden as measured by hospitalization rates. Methods We used weekly SARS-CoV-2 wastewater concentration with a stratified random sampling of seroprevalence, and spatially linked vaccination and hospitalization data, from April to August 2021. Our susceptible ( S ), vaccinated ( V ), variant-specific infected (I1 and I2), recovered ( R ), and seropositive ( T ) model ( SVI 2 RT ) tracked prevalence longitudinally. This was related to wastewater concentration for a spatial analysis of strain mutation, vaccination effect, and overall hospitalization burden. Findings We found strong linear association between wastewater concentration and estimated community prevalence (r=0·916). Based on the corresponding regression model, the 64% county vaccination rate translated into about 57% decrease in SARS-CoV-2 incidence. During the study period, the estimated effect of SARS-CoV-2 Delta variant emergence was seen as an over 7-fold increase of infection counts, which corresponded to over 12-fold increase in wastewater concentration. Hospitalization burden and wastewater concentration had the strongest correlation (r=0·963) at 1 week lag time. We estimated the community vaccination campaign resulted in about 63% reduction in the number of daily admissions over the study period. This protective effect was counteracted by the emergence of SARS-CoV-2 Delta strain mutation. Interpretation Wastewater samples can be used to estimate the effects of vaccination and hospitalization burden. Our study underscores the importance of continued environmental surveillance post-vaccine and provides a proof of concept for environmental epidemiology monitoring. Funding Centers for Disease Control and Prevention (75D30121C10273), Louisville Metro Government, James Graham Brown Foundation, Owsley Brown II Family Foundation, Welch Family, Jewish Heritage Fund for Excellence, the National Institutes of Health, (P20GM103436), the Rockefeller Foundation, and the National Sciences Foundation (DMS-2027001). Evidence before this study We searched Web of Science and PubMed for all available articles until August 24, 2022, using the search terms [“seroprevalence” or “antibody”] AND [“wastewater”] AND [“vaccination”]. We examined only English literature. We identified 59 studies. None of these studies considered community level randomized antibody testing paired with vaccination and SARS-CoV-2 wastewater concentration data. Where wastewater and vaccination status have been historically linked is with Poliomyelitis , in the known spatial scale of vaccination rates and using wastewater surveillance to confirm presence/absence of community infection. Few studies considered hepatitis A antibodies in workers exposed to sewage to guide vaccination campaigns. We also found some non-human subject research. To our knowledge, there is no real-world setting SARS-CoV-2 study where quantified wastewater concentration is linked to a large longitudinal stratified randomized seroprevalence sampling at a sub-population scale and the population has voluntary access to a vaccination reducing hospitalization burden. Added value of this study To our knowledge, this study provides the first analysis of SARS-CoV-2 wastewater concentration as the basis for estimating subpopulation vaccination and virus mutation effects, and hospitalization burden in any country. We used actual seroprevalence data from a large US urban area that was rigorously collected through statistical sampling, to obtain a longitudinal estimate of disease prevalence. We then used a statistical model relating prevalence to wastewater concentration for a spatial analysis of vaccination, virus mutation effects, and for forecasting hospitalization burden. The methodology developed in the current paper has a potential to improve both the effectiveness of monitoring and the predictive accuracy of wastewater-based surveillance systems. Implications of all the available evidence Our results show the potential of sustained environmental surveillance post-vaccine in urban areas and on removing bias in population-level estimates of prevalence of SARS-CoV-2 due to over-reliance on reported clinical testing data. The methodology presented here provides further proof wastewater monitoring can be successfully used as a tool for estimating both the community impact of changing disease patterns and various interventions over time. These findings have implications beyond current SARS-CoV-2 pandemic since our proposed approach is quite general and can be applied to other vaccine preventable diseases affecting human health in the absence of clinical testing data. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Centers for Disease Control and Prevention (75D30121C10273), Louisville Metro Government, James Graham Brown Foundation, Owsley Brown II Family Foundation, Welch Family, Jewish Heritage Fund for Excellence, the National Institutes of Health, (P20GM103436), the Rockefeller Foundation, and the National Sciences Foundation (DMS-2027001). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: For the seroprevalence and data provided by the LMPHW under a Data Transfer Agreement, the University of Louisville Institutional Review Board approved this as Human Subjects Research (IRB number: 20.0393). For the wastewater data, the University of Louisville Institutional Review Board classified this as non-human subjects research (reference #: 717950).   I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The seroprevalence, wastewater concentration, and hospitalization information data used in the study can be accessed from the website . The computer code that implemented our model-based analysis will be made available immediately after publication.