Researchers from Harvard Medical School have been analysing increased hospital traffic from the country.
Some scientists believe Covid-19 might have been spreading in China as early as August last year.
Researchers at the Harvard Medical School in the US have been analysing increased hospital traffic and search engine data from the country.
They say the evidence supports claims the virus emerged before it was identified at a market in Wuhan.
"Increased hospital traffic and symptom search data in Wuhan preceded the documented start of the SARS-CoV-2 pandemic in December 2019," the research states.
"While we cannot confirm if the increased volume was directly related to the new virus, our evidence supports other recent work showing that emergence happened before identification at the Huanan Seafood market."
"These findings also corroborate the hypothesis that the virus emerged naturally in southern China and was potentially already circulating at the time of the Wuhan cluster."
To date, the coronavirus has infected more than 7.2 million people and claimed over 411,000 lives.
