The WHO investigation team in China found 13 nCoV variants in Wuhan during the late 2019 outbreak, suggesting that the disease may be larger than reported.

Information was investigator of the delegation of the World Health Organization Peter Ben Embarek said on 14/2.

Data from the WHO mission trip may add to concerns among scientists working on the origin of Covid-19.

The WHO expert added that the delegation was presented by Chinese scientists on 174 nCoV infections in Wuhan city and surrounding areas in December 2019.

The data above suggests Covid-19 may have affected more than 1,000 people in Wuhan by the end of December 2019, and Chinese doctors may only pay early attention to serious infections such as, Embarek said.

"We have not made any predictive modeling since then. But we know, in the data of people infected with nCoV, about 15% of the cases are advanced, and most are mild cases.

The WHO expert added that their delegation was also able to collect 13 different gene sequences of nCoV since December 2019.

"Some come from the marketplaces, but others are not. This is something we have found as part of our mission," Embarek said of the nCoV strains.

Changes in the genetic makeup of viruses are common and often harmless, occurring over time as disease passes between humans or animals.

However, the discovery of so many different variants of nCoV may also indicate that the virus has been around for longer in December 2019, as some virologists have previously suggested.

"Since there was genetic diversity in the nCoV sequences sampled from Wuhan in December 2019, it is likely that the virus has been circulating for longer than just one month," says Giao.

Holmes, who has studied the timing of the occurrence of nCoV, said the 13 strains of the virus could indicate that nCoV had been undetected for a while before the outbreak in Wuhan, of which the first time

The WHO's international team of experts just ended their investigation in Wuhan city, where Covid-19 started, with an assessment that there was insufficient evidence to conclude that nCoV had spread in Wuhan before December 2019,

Dominic Dwyer, an Australian expert and also a member of the WHO investigation team, said China refused to provide raw data on the first 174 nCoV cases in Wuhan, including details on the

UK and US have expressed concern about the WHO Covid-19 investigation, especially about the level of information access provided by the group to the Chinese side.