An Italian study supporting the case that the novel coronavirus was circulating outside China earlier than previously thought has sparked doubts among some Western scientists who called for further tests.

The paper published by the Italian Cancer Institute (INT) describes the presence of neutralising antibodies to SARS-CoV-2 in blood taken from a small number of healthy patients in Italy in October last year during a lung cancer screening trial.

If the data are correct, they would change the history of the pandemic and raise questions of when and where the virus emerged.

Currently it is thought it was first identified in the central Chinese city of Wuhan in December 2019.