The places people at risk of transmitting infection come from is getting bigger daily. The graph above shows the explosion in cases is mostly outside China. Ive got another somewhere that shows Covid-19 is spreading way faster than any other previous virus like Ebola or the 2003 SARS Coronavirus or MERS.
It only needs someone who is shedding virus to come into Heathrow and catch the tube into London at rush hour and its game over.
2-14 days represents the current official estimated range for the novel coronavirus COVID-19. However, a case with an incubation period of 27 days has been reported by Hubei Province local government on Feb. 22  In addition, a case with an incubation period of 19 days was observed in a JAMA study of 5 cases published on Feb. 21.  An outlier of a 24 days incubation period had been for the first time observed in a Feb. 9 study. WHO said at the time that this could actually reflect a second exposure rather than a long incubation period, and that it wasn't going to change its recommendations. Period can vary greatly among patients. Mean incubation period observed: 3.0 days (0 - 24 days range, study based on 1,324 cases) 5.2 days (4.1 - 7.0 days range, based on 425 cases). Mean incubation period observed in travelers from Wuhan: 6.4 days (range from 2.1 to 11.1 days).