Occurrence of Human Viruses on Fomites in the Environment: A Systematic Review and Meta-analysis

Documenting the occurrence of viruses on fomites is crucial in determining the significance of fomite-mediated transmission and the potential use of fomites for environmental disease surveillance. We conducted a systematic review and meta-analysis to compile information on the occurrence of human viruses on fomites in the environment; we identified 134 peer-reviewed papers. We compiled sampling and measurement methods, results, quality control information, and whether virus data were compared with community health data from the papers. We conducted univariate and multivariate analyses to investigate if presence of virus on fomites was associated with virus type (enveloped, nonenveloped), sampling location (healthcare setting, nonhealthcare temporary setting, nonhealthcare nontemporary setting), and area of fomite swabbed (<50, 50-100, >100 cm2). Across 275 data sets from the 134 papers, there was the most data available for Coronaviridae and from fomites at hospitals. Positivity rates, defined as the percent positive fomite samples, were low (median = 6%). Data were available on viruses from 16 different viral families, but data on viruses from 9 families had few (n < 5) data sets. Many human virus families were not identified in this review (11 families). Less than 15% of the data sets reported virus concentrations in externally valid units (viruses per area of surface), and 16% provided a quantitative comparison between virus and health data. Virus type and area swabbed were significant predictors of virus presence on fomites, and the positivity rate of data sets collected from healthcare settings and nonhealthcare nontemporary settings (e.g., individual housing) were significantly higher than those collected in nonhealthcare temporary settings (e.g., restaurants). Data from this review indicates that viruses may be present on fomites, that fomite-mediated virus transmission may occur, and that fomites may provide information on circulation of infectious diseases in the community. However, more quantitative data on diverse viruses are needed, and method reporting needs significant improvements.

Investigating the Efficacy of Various Handwashing Methods against Enveloped and Non-Enveloped Viruses

Respiratory and diarrheal diseases are leading causes of death worldwide. Handwashing may reduce disease; however, recommended methods (soap and water for 20 seconds) are not always possible, particularly in low-resource settings. The aim of this study is to evaluate handwashing when recommended methods are not feasible, including washing with water only, washing with soapy water, washing for a short duration, using alcohol-based hand sanitizer (ABHS), and cleaning hands with towels. To evaluate laboratory efficacy, we seeded MS2 (a non-enveloped virus) and Phi6 (an enveloped virus) onto the hands of volunteers who then washed their hands. Viruses remaining were recovered and quantified using culture-based and molecular methods to determine the log reduction value (LRV) after washing. Results indicated that washing with water only and with soapy water were similar to washing with soap and water for 20 seconds for both viruses (median LRV for MS2 = 2.8; Phi6 = 3.2). Most towel alternative conditions had LRVs significantly smaller than LRVs from washing with soap and water for either virus. LRVs of ABHS and soap and water for 5 seconds were similar to soap and water for 20 seconds for Phi6 but less for MS2 (median MS2 LRV differences = 2.5 and 0.51 for ABHS and soap and water for 5 seconds, respectively). Additionally, LRVs determined using molecular methods were in agreement with those obtained using culture-based methods. These results suggest some handwashing alternatives were as effective as recommended methods whereas others were not, and inform recommendations and future research on handwashing alternatives in low-resource settings.

Quantifying the Viral Reduction Achieved Using Ash and Sand as Handwashing Agents

The WHO recommends handwashing with soap and water for 20-40 seconds. In settings where soap is not available, ash or sand is used for handwashing, yet their efficacy as handwashing materials is underresearched. The purpose of this study was to quantify the removal of viruses using ash and sand as handwashing agents, and compare their efficacy to commonly recommended handwashing methods. We performed a volunteer study to estimate the log reduction value (LRV) of model viruses Phi6 and MS2 on hands after six handwashing conditions: two handwashing agents (ash and water, and sand and water) with two time points (5 and 20 seconds), and two handwashing agents (soap and water, and water only) with one time point (20 seconds). Plaque assays were used to measure infectious virus reduction. Handwashing with any of the handwashing agents for 20 seconds resulted in a greater LRV than the 2-log reduction U.S. Food and Drug Administration criteria for both viruses. Soap and water resulted in a significantly greater LRV (2.7-4.8) than washing with ash and water (2.0-2.8) or sand and water (1.8-2.7) for 5 seconds for both viruses, and water only resulted in a significantly higher LRV (2.8) than all ash (2.0-2.6) and sand (1.8-2.4) conditions for MS2 only. These results suggest that using ash or sand as handwashing agents can be efficacious in reducing viruses but may be less efficacious than soap, especially when used for shorter durations. Further research should investigate the use of ash and sand as handwashing agents in real-world settings.

SARS-CoV-2 RNA and N Antigen Quantification via Wastewater at the Campus Level, Building Cluster Level, and Individual-Building Level

Monitoring wastewater for SARS-CoV-2 from populations smaller than those served by wastewater treatment plants may help identify small spatial areas (subsewersheds) where COVID-19 infections are present. We sampled wastewater from three nested locations with different sized populations within the same sewer network at a university campus and quantified SARS-CoV-2 RNA using reverse transcriptase droplet digital polymerase chain reaction (PCR). SARS-CoV-2 RNA concentrations and/or concentrations normalized by PMMoV were positively associated with laboratory-confirmed COVID-19 cases for both the sewershed level and the subsewershed level. We also used an antigen-based assay to detect the nucleocapsid (N) antigen from SARS-CoV-2 in wastewater samples at the sewershed level. The N antigen was regularly detected at the sewershed level, but the results were not associated with either laboratory-confirmed COVID-19 cases or SARS-CoV-2 RNA concentrations. The results of this study indicate that wastewater monitoring based on quantification of SARS-CoV-2 RNA using PCR-based methods is associated with COVID-19 cases at multiple geographic scales within the subsewershed level and can serve to aid the public health response.

Scaling of SARS-CoV-2 RNA in Settled Solids from Multiple Wastewater Treatment Plants to Compare Incidence Rates of Laboratory-Confirmed COVID-19 in Their Sewersheds

Published and unpublished reports show that SARS-CoV-2 RNA in publicly owned treatment work (POTW) wastewater influent and solids is associated with new COVID-19 cases or incidence in associated sewersheds, but methods for comparing data collected from diverse POTWs to infer information about the relative incidence of laboratory-confirmed COVID-19 cases, and scaling to allow such comparisons, have not been previously established. Here, we show that SARS-CoV-2 N1 and N2 concentrations in solids normalized by concentrations of PMMoV RNA in solids can be used to compare incidence of laboratory confirmed new COVID-19 cases across POTWs. Using data collected at seven POTWs along the United States West Coast, Midwest, and East Coast serving ∼3% of the U.S. population (9 million people), we show that a 1 log change in N gene/PMMoV is associated with a 0.24 (range 0.19 to 0.29) log10 change in incidence of laboratory confirmed COVID-19. Scaling of N1 and N2 by PMMoV is consistent, conceptually, with a mass balance model relating SARS-CoV-2 RNA to the number of infected individuals shedding virus in their stool. This information should support the application of wastewater-based epidemiology to inform the response to the COVID-19 pandemic and potentially future viral pandemics.

Effects of an urban sanitation intervention on childhood enteric infection and diarrhea in Maputo, Mozambique: A controlled before-and-after trial

We conducted a controlled before-and-after trial to evaluate the impact of an onsite urban sanitation intervention on the prevalence of enteric infection, soil transmitted helminth re-infection, and diarrhea among children in Maputo, Mozambique. A non-governmental organization replaced existing poor-quality latrines with pour-flush toilets with septic tanks serving household clusters. We enrolled children aged 1-48 months at baseline and measured outcomes before and 12 and 24 months after the intervention, with concurrent measurement among children in a comparable control arm. Despite nearly exclusive use, we found no evidence that intervention affected the prevalence of any measured outcome after 12 or 24 months of exposure. Among children born into study sites after intervention, we observed a reduced prevalence of Trichuris and Shigella infection relative to the same age group at baseline (<2 years old). Protection from birth may be important to reduce exposure to and infection with enteric pathogens in this setting.