Each patient infected with coronavirus passes the illness to between two and three other people, on average, at current transmission rates, according to two separate analyses of the epidemic.

Control measures would have to halt transmission in at least 60% of cases to contain the spread of the epidemic, the researchers say.

One of the studies, co-led by Professor Neil Ferguson, an infectious disease specialist at Imperial College London, suggests as many as 4000 people in Wuhan were already infected by 18 January.

Each case would have infected between two and three people, according to their analysis, which is based on past estimates of the size of the outbreak in Wuhan and modelling of potential epidemic trajectories.