Fact check: Researchers found coronavirus in March 2019 wastewater; more study needed

The claim: Traces of coronavirus were found in samples of wastewater collected before pandemic 

As scientists rush to understand and fight against the novel coronavirus, a new claim suggests it may have been around a year before the pandemic started.

"This week, researchers at the University of Barcelona have published new findings that suggest the virus that causes COVID-19 has been found in sewage samples from March of 2019," a June 28 Facebook post states.

The original article published by Truth Theory, a UK-based website, emphasized the likelihood of this finding by suggesting "people who caught the illness could have been misdiagnosed with the flu" as a bad flu season was a legitimate health concern prior to the pandemic.  

USA TODAY is awaiting comment from the author of the original article. 

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Coronavirus likely in wastewater 

The University of Barcelona, as cited by the Truth Theory article, did indeed find evidence of the novel coronavirus in wastewater. The study, which comes after many others using wastewater to monitor potential coronavirus outbreaks, tested samples collected months to a year before March 2020. The first positive sample was obtained on Jan. 15, 2020, 41 days before the first official case was declared in Spain on Feb. 25. Other archival samples collected up to March 2019 returned negative; a March 12, 2019, sample returned positive for the novel coronavirus.    

“The levels of SARS-CoV-2 were low but were positive,” research leader Albert Bosch was quoted as saying by the university.    

The scientific caveats      

Spain is not alone in this newest finding: studies out of Italy and Brazil have also suggested coronavirus may have been circulating earlier than thought. But there is reason to be cautious. 

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While a positive result could entail a true positive – that novel coronavirus was actually detected – it could also mean contamination of the test sample (which can happen in labs regularly handling positive specimens) or a false positive.

"When it’s just one result, you always want more data, more studies, more samples to confirm it and rule out a laboratory error or a methodological problem," said Dr. Joan Ramon Villalbi of the Spanish Society for Public Health and Sanitary Administration in an interview with Reuters. 

It is also important to note that this finding runs contrary to epidemiological data.

"The authors don’t cite reports of a spike in the number of respiratory disease cases in the local population following the date of the sampling," Dr. Clare Crossan, a lecturer in virology at Glasgow Caledonian University, writes in an article for The Conversation. 

"Also, we know SARS-CoV-2 to be highly transmissible, at least in its current form. If this result is a true positive, it suggests the virus was present in the population at a high enough incidence to be detected in an 800ml sample of sewage, but then not present at a high enough incidence to be detected for nine months, when no control measures were in place," Crossan further adds.  

The University of Barcelona study, as well as those out of Italy and Brazil, is in preprint and awaiting peer review.   

Our ruling: More information needed

The claim that novel coronavirus was discovered in wastewater samples predating the pandemic needs more information before it can be fully rated, based on our research. It is true that a sample yielded a positive result in testing for coronavirus. However, a positive finding can result from a variety of scenarios, including contamination from a positive sample or a false positive. Additionally, these findings have not yet been peer-reviewed and no definitive conclusion should be made until more studies are done.  

Our fact-check sources:

• Media Bias/Truth Check, "Truth Theory"
• medRxiv, "Sentinel surveillance of SARS-CoV-2 in wastewater anticipates the occurrence of COVID-19 cases"
• Science Magazine, "Coronavirus found in Paris sewage points to early warning system."
• Reuters, "TIMELINE-How the coronavirus spread in Spain"
• Bloomberg, "Italy Had Coronavirus in Sewage as Early as December, Study Says"
• medRxiv, "SARS-CoV-2 in human sewage in Santa Catalina, Brazil, November 2019"
• Reuters, "Coronavirus traces found in March 2019 sewage sample, Spanish study shows"
• The Conversation, "Was coronavirus really in Europe in March 2019?"

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Our fact check work is supported in part by a grant from Facebook.