The results show that medics significantly underestimate the overall ability of the virus to mutate, finding that different variants have affected different parts of the world, leading to potential difficulties in finding complete treatment.

The study was conducted by Professor Li Lanjuan and his colleagues at the University of Hangzhou, China, and published on the medRxiv.org website.

Li's team analyzed samples from 11 randomly selected patients with coronavirus from Hangzhou, where there were 1264 reported cases, and then tested how effectively they could infect and kill cells.

Over 30 different mutations were detected, 19 of which were previously undetected.

"SARS-CoV-2 has acquired mutations capable of substantially changing its pathogenicity," Li wrote in the article.

The team has discovered that some of the mutations can lead to functional changes in the protein it uses to attach itself to human cells, according to the South China Morning Post.

Cells infected with COVID-19 strains infected by the Li team carrying different mutations, of which the most aggressive strains generated 270 times more viral load than the weakest strains. Aggressive strains kill human cells the fastest.

The results show that "the true diversity of the viral strains is still largely underappreciated" Li writes.

The study may have future implications for the treatment of coronavirus, as several different strains have been identified worldwide.

The United States, which has the highest number of casualties - 42,897 out of 799,515 infected people - is affected by various mutations. New York, which itself has the highest mortality rate in the US, and the east coast show a coronavirus strain similar to that found in Europe, while the western states show similarities to the strains found in China.