A study published in JAMA Network Open discovered an association between clinical cases of COVID-19 and viral loads in wastewater. The viral loads increased up to two days before COVID cases were confirmed. This study is significant, because it is one of the first to use wastewater analysis to track the spread of a respiratory virus.
The data reported is from the testing that took place at the Tokyo 2020 Olympics and Paralympics from July 21 to September 21, 2021. The Olympic events took place during a time when the incidence and spread of COVID-19 was very prevalent, so a multi-pronged testing approach was used for the purposes of curbing viral infection at the games. Daily data collection of COVID testing of athletes and staff at the Olympic and Paralympic Villages included testing viral loads in the sewage system’s wastewater. The results were then shared with the Tokyo 2020 Organizing Committee.
The study correlated the results of 360 samples collected from manholes in 7 different areas of the village with confirmed SARS-CoV-2 clusters obtained from the Organizing Committee (a COVID cluster is defined here as two or more cases of an infection from the same source of exposure). Data of close contacts tests from a previous report were also analyzed.
The researchers found that SARS-CoV-2 was present in 151 wastewater samples (53 from the Olympics and 98 from the Paralympics). Areas that had maximum viral loads in wastewater in a three-day span (two days before to the day of detection of clinical positive area) showed a significant correlation between SARS-CoV-2 RNA load in wastewater and clinical positive areas.
The study indicated that the testing strategy played a role in preventing and predicting outbreaks in the two villages. This approach focuses on assessing viral RNA measures in wastewater, and could be used as a strategy to trace and reduce COVID infection in similar large events.
Using wastewater analysis to predict COVID spread is a cost-effective and nonintrusive method of collecting data and predicting case outbreaks. SARS-CoV-2 can be detected in the digestive system sheds in high quantities prior to an infected person becoming symptomatic.