Even within a given jurisdiction, clinical testing policies may change over time. However, clinical testing is subject to local and regional policies which can restrict the availability and accessibility of clinical testing. (14) Thus, to contain the SARS-CoV-2 pandemic, accurate and timely diagnostic testing is critical to guide quarantine and self-isolation of patients and potential carriers. (1,12,13) However, the incubation period may vary from person to person and the incubation period can be extended up to 27 days. (1)Īccording to the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC), the estimated incubation period of SARS-CoV-2 ranges from 1–14 days with a median period of 5–6 days between the time of infection and the onset of symptoms. (7) As of July 25, 2021, SARS-CoV-2 and new variants have infected over 192,000,000 cases and over 4.1 million deaths across the globe. (2−6) Recently, the Delta (B.1.617.2) variant is emerging and is responsible for the recent surge in local cases in many countries. These variants have demonstrated increased transmissibility, disease severity, and mortality, and they may also reduce the effectiveness of current therapeutics and vaccines. Additionally, genetic variants, notably Alpha (B.1.1.7), Beta (B.1.351), and Gamma (P.1), are the main variants that are becoming the predominant strains in many countries. With new variants emerging and spreading globally, the control of SARS-CoV-2 remains challenging. (1) This damage is unprecedented and worsening as the number of SARS-CoV-2 infections continues to rise in many countries. The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has severely damaged the state of global public health, economies, and overall societies. Critical analysis of the published studies reveals imperative research needs for the development, validation, and standardization of robust and sensitive methods for quantitative detection of viral RNA and proteins in wastewater for WBE. We emphasize the importance of implementing appropriate controls and method validation, which include the use of surrogate viruses for assessing extraction efficiency and normalization against measurable chemical and biological components in wastewater.
![ishikawa diagram water and sanitation ishikawa diagram water and sanitation](http://hislides.az0pg5xoql0a2.maxcdn-edge.com/Elements/117P_1/01-fish-bone-simple-ppt-1.png)
Efficient extraction of the viral RNA and removal of interfering sample matrices are critical to the subsequent reverse transcription-quantitative polymerase chain reaction (RT-qPCR) for sensitive detection of SARS-CoV-2 in wastewater. We discuss advantages and limitations of available methods for wastewater sample processing, including collection, separation, enrichment, RNA extraction, and purification. Very low concentrations of viral particles and RNA present in the complicated wastewater and sewage sample matrix require efficient sample processing and sensitive detection. In this Review, we summarize recent progress and highlight remaining challenges in monitoring SARS-CoV-2 RNA in wastewater systems for community and environmental surveillance. Wastewater-based epidemiology (WBE) is useful for the surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in communities, complementing clinical diagnostic testing of individuals.