In a new paper, the researchers reveal that the concentration of viral RNA in sludge can also serve as an early indicator of an outbreak—a canary in the sewer pipes, as it were—revealing a worsening crisis three to five days before patients with severe disease will require hospitalization. What’s more, the team was able to get an estimate of the virus’s basic reproduction number (that is, how many other people a typical person infected with coronavirus is able to infect) with over six weeks’ worth of wastewater data.
The model tells a story: On Day 0, patients are infected. By Day 3, they’ve begun to excrete viral RNA. By Day 9, that RNA can be detected in sewage. By Day 12, if patients are unlucky, they arrive at Yale New Haven Hospital. Essentially, measuring wastewater offers at least three days of crucial lead time.