Clinical Scorecard: SARS-CoV-2 Levels in Wastewater Effectively Forecast the Incidence of Symptomatic Infections in the Community

At a Glance

Key Highlights

• SARS-CoV-2 RNA levels in wastewater accurately predict symptomatic COVID-19 case counts in the community one week later (P = .001).
• Wastewater surveillance remains a valuable tool for monitoring community infection trends despite changes in hospitalization predictive ability due to widespread immunity.
• Monitoring wastewater can aid in workforce planning by forecasting employee illness surges, especially in health care systems.

Guideline-Based Recommendations

Diagnosis

• Use quantitative reverse transcription PCR targeting SARS-CoV-2 Orf1ab gene in wastewater samples for community surveillance.

Management

• Incorporate wastewater SARS-CoV-2 surveillance data to anticipate symptomatic infection surges and implement timely public health interventions.
• Use surveillance data to inform workforce management and precautionary measures in health care and other large organizations.

Monitoring & Follow-up

• Collect and analyze 24-hour composite wastewater influent samples regularly to track SARS-CoV-2 RNA levels.
• Correlate wastewater viral load data with symptomatic case reports to monitor community infection dynamics.

Risks

• Reduced predictive ability of wastewater viral levels for hospitalizations due to widespread immunity and home testing limiting official case reporting.
• Potential variability in viral RNA detection due to variant-specific genomic changes affecting PCR targets (e.g., S gene dropout).

Patient & Prescribing Data

Health care employees residing within the wastewater catchment area who tested positive for SARS-CoV-2.

Wastewater viral load correlates with symptomatic infection incidence but does not directly inform individual treatment decisions.

Clinical Best Practices

• Partner with occupational health services to obtain deidentified symptomatic case data for correlation with wastewater surveillance.
• Use Orf1ab gene target for quantitative PCR analysis due to better reliability over N gene in wastewater samples.
• Maintain regular sampling intervals (e.g., weekly) to provide timely predictive data for community infection trends.
• Consider variant-specific PCR target limitations (e.g., S gene dropout) when interpreting wastewater surveillance results.

References

• Wastewater surveillance for polio and other pathogens
• Early SARS-CoV-2 wastewater monitoring as a predictor of hospitalizations
• Minnesota SARS-CoV-2 wastewater surveillance data