In a new unpublished study by the University of Barcelona, scientists have reported that the novel coronavirus was present in wastewater in Barcelona, Spain, in March 2019. If proven to be true, this could mean that the virus was present long before any case of COVID-19 was reported.

However, several independent experts are skeptical about the research. They said that it is flawed, and other evidence still strongly suggests that the virus first emerged in China in the later part of 2019.

According to the study's lead author, Albert Bosch, a microbiology professor at the University of Barcelona who has been conducting studies in wastewater for more than 40 years, Chinese people usually visit the city to tour and do business. Additionally, this could also be true to other places that the Chinese people have visited.

Coronavirus in Wastewater

Scientists have struggled to find the origin of the virus. So far, the earliest evidence point to Wuhan. China, where the first cases of the virus were reported in December 2019.

Researchers have examined the mutations of the novel coronavirus around the world and estimated the basis of their findings that they share a common ancestor that dated to late 2019. As the months pass by, more evidence suggests that the origin of the virus came from animals, particularly in bats and other wild animals sold in the Chinese market.

Furthermore, there were also reports that coronavirus can be found in the feces. These led some researchers to begin examining wastewater to detect if coronavirus lives there.

Researchers posted their results online on June 13, which mostly described their research in wastewater in 2020. Meanwhile, researchers discovered rising levels of the virus's genes in wastewater in Europe, Australia, and the United States days before anyone knew to look for it.

Just last week, researchers reported that they found the virus in Milan and Turin on December 18, two months before COVID-19 plagued the country.

In a separate study, Dr. Bosch and his team took weekly wastewater samples from two of Barcelona's treatment plans in April. They found that the coronavirus is present in the samples collected, which prompted them to look back at earlier samples of wastewater.

Dr. Bosch believes that it is possible that coronavirus might be present in March but not show up in more recent samples. He said that the virus usually peaks around this time of the year, and the virus back then might have already disappeared.

Some Experts are Doubtful

a "big, if true" from @carlzimmer: Study Suggests Coronavirus Emerged Much Earlier Than Thought. But Some Scientists Are Skeptical. https://t.co/SyekuYrajs — Virginia Hughes (@virginiahughes) June 26, 2020According to the New York Times, several independent experts pointed out the problems of the new study, which has not undergone any review yet from outside experts before its publication in a scientific journal. The experts think that there might be problems in storing the samples, and the contamination has also participated in getting a false-positive result.

"I don't trust the results," said Irene Xagoraraki, an environmental engineer at Michigan State University.

She noted that the researchers only used tests that search for bits of three different genes. Moreover, she said that the test can only come back positive when the gene RdRp is present. One of the tests used in the study that looks for gene N is known to be more sensitive.

"It should have shown a signal as well," Dr. Xagoraraki said.

Though many experts are skeptical, Gertjan Medema of the KWR Water Research Institute in the Netherlands said that the research came from a reputable team and should be taken seriously. But she also said that tests should be done first to confirm these findings.