Separating signal from noise in wastewater data: An algorithm to identify community-level COVID-19 surges in real time.

Wastewater monitoring has provided health officials with early warnings for new COVID-19 outbreaks, but to date, no approach has been validated to distinguish signal (sustained surges) from noise (background variability) in wastewater data to alert officials to the need for heightened public health response. We analyzed 62 wk of data from 19 sites participating in the North Carolina Wastewater Monitoring Network to characterize wastewater metrics around the Delta and Omicron surges. We found that wastewater data identified outbreaks 4 to 5 d before case data (reported on the earlier of the symptom start date or test collection date), on average. At most sites, correlations between wastewater and case data were similar regardless of how wastewater concentrations were normalized and whether calculated with county-level or sewershed-level cases, suggesting that officials may not need to geospatially align case data with sewershed boundaries to gain insights into disease transmission. Although wastewater trend lines captured clear differences in the Delta versus Omicron surge trajectories, no single wastewater metric (detectability, percent change, or flow-population normalized viral concentrations) reliably signaled when these surges started. After iteratively examining different combinations of these three metrics, we developed the Covid-SURGE (Signaling Unprecedented Rises in Groupwide Exposure) algorithm, which identifies unprecedented signals in the wastewater data. With a true positive rate of 82%, a false positive rate of 7%, and strong performance during both surges and in small and large sites, our algorithm provides public health officials with an automated way to flag community-level COVID-19 surges in real time.

Monitoring SARS-CoV-2 RNA in wastewater from a shared septic system and sub-sewershed sites to expand COVID-19 disease surveillance.

Wastewater-based epidemiology has expanded as a tool for collecting COVID-19 surveillance data, but there is limited information on the feasibility of this form of surveillance within decentralized wastewater systems (e.g., septic systems). This study assessed SARS-CoV-2 RNA concentrations in wastewater samples from a septic system servicing a mobile home park (66 households) and from two pumping stations serving a similarly sized (71 households) and a larger (1,000 households) neighborhood within a nearby sewershed over 35 weeks in 2020. Also, raw wastewater from a hospital in the same sewershed was sampled. The mobile home park samples had the highest detection frequency (39/39 days) and mean concentration of SARS-CoV-2 RNA (2.7 × 107 gene copies/person/day for the N1) among the four sampling sites. N1 gene and N2 gene copies were highly correlated across mobile home park samples (Pearson's r = 0.93, p < 0.0001). In the larger neighborhood, new COVID-19 cases were reported every week during the sampling period; however, we detected SARS-CoV-2 RNA in 12% of the corresponding wastewater samples. The results of this study suggest that sampling from decentralized wastewater infrastructure can be used for continuous monitoring of SARS-CoV-2 infections.

Timing and Trends for Municipal Wastewater, Lab-Confirmed Case, and Syndromic Case Surveillance of COVID-19 in Raleigh, North Carolina.

Objectives. To compare 4 COVID-19 surveillance metrics in a major metropolitan area. Methods. We analyzed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater influent and primary solids in Raleigh, North Carolina, from April 10 through December 13, 2020. We compared wastewater results with lab-confirmed COVID-19 cases and syndromic COVID-like illness (CLI) cases to answer 3 questions: (1) Did they correlate? (2) What was the temporal alignment of the different surveillance systems? (3) Did periods of significant change (i.e., trends) align? Results. In the Raleigh sewershed, wastewater influent, wastewater primary solids, lab-confirmed cases, and CLI were strongly or moderately correlated. Trends in lab-confirmed cases and wastewater influent were observed earlier, followed by CLI and, lastly, wastewater primary solids. All 4 metrics showed sustained increases in COVID-19 in June, July, and November 2020 and sustained decreases in August and September 2020. Conclusions. In a major metropolitan area in 2020, the timing of and trends in municipal wastewater, lab-confirmed case, and syndromic case surveillance of COVID-19 were in general agreement. Public Health Implications. Our results provide evidence for investment in SARS-CoV-2 wastewater and CLI surveillance to complement information provided through lab-confirmed cases. (Am J Public Health. 2023;113(1):79-88. https://doi.org/10.2105/AJPH.2022.307108).

Characteristics of an Outbreak of E-cigarette, or Vaping, Product Use-Associated Lung Injury-North Carolina, 2019.

BACKGROUND In August 2019, the North Carolina Division of Public Health (NCDPH) began investigating e-cigarette, or vaping, product use-associated lung injury (EVALI) cases as part of a national response. We describe clinical, epidemiologic, and laboratory findings of North Carolina EVALI patients.METHODS NCDPH requested that physicians report cases of respiratory illness or bilateral pulmonary infiltrates or opacities in patients who reported using e-cigarette, or vaping, products and had no infection or alternative plausible diagnoses. We reviewed medical records, interviewed patients, and tested vaping products for substances.RESULTS During August 13, 2019-February 18, 2020, 78 EVALI cases were reported in North Carolina. Median age of cases was 24 years (range: 13-72 years); 49 (63%) patients were male. Symptoms included cough (n = 70; 90%), shortness of breath (n = 66; 85%), and gastrointestinal symptoms (n = 63; 81%). Seventy-five patients (96%) were hospitalized, 32 (41%) required intensive care, and 12 (16%) required mechanical ventilation; none died. Among 20 patients interviewed, most reported using tetrahydrocannabinol (THC) (n = 16; 80%) or nicotine-containing products (n = 14; 70%). All obtained THC-containing products from informal sources, such as family, friends, or dealers, as THC is illegal in North Carolina. Among 82 products tested, 74 (90%) contained THC, cannabidiol, or cannabinol; 54 (66%) contained vitamin E acetate.LIMITATIONS In North Carolina, EVALI is not reportable by law, and THC is illegal. Thus, cases and exposures are likely underreported.CONCLUSIONS THC-containing products, particularly those containing vitamin E acetate, are associated with EVALI. Persons should not use these products, particularly from informal sources. Continued communication of health risks to persons who use e-cigarette, or vaping, products is essential.