Spanish virologists believe they may have found traces of COVID-19 in a sample of waste water collected in Barcelona in March of last year.
If that is proven to be the case, it would mean the discovery was made nine months before the coronavirus was first identified in China.
Dr Joan Ramon Villalbi of the Spanish Society for Public Health and Sanitary Administration said it is a single sample, however, and more would be needed to confirm the result.
Despite there being the potential for a false positive, because of the virus’s similarities with other respiratory infections, Dr Villalbi said the finding was “definitely interesting and suggestive”.
The research has been submitted for peer review after the sample was found by a team from the University of Barcelona, which has been testing waste water since mid-April.
Sewage samples taken in Italy suggest the virus may have been there as early as December.
It is thought COVID-19 may have been present in France in the same month.