- For the data to show an outbreak, there has to be widespread testing.
- For testing to reflect rapid spread, people must seek testing.
- People must feel ill before they seek testing, but many infected people have no symptoms.
Peccia et al., 2020
The red line shows viral concentration. The grey represents confirmed COVID-19 cases. The virus showed up in the sewage a full week before testing revealed climbing case counts.
The study referenced above is SARS-CoV-2 RNA concentrations in primary municipal sewage sludge as a leading indicator of COVID-19 outbreak dynamics by Jordan Peccia, Alessandro Zulli, Doug E. Brackney, Nathan D. Grubaugh, Edward H. Kaplan, Arnau Casanovas-Massana, Albert I. Ko, Amyn A. Malik, Dennis Wang, Mike Wang, Daniel M. Weinberger, Saad B. Omer, a preprint study. This article has not yet been peer-reviewed.