A German man acquired the infection from a colleague who had returned from Wuhan, according to news reports and a statement from Bavaria’s health ministry. In a 27 January update, the World Health Organization confirmed that a person in Vietnam acquired the virus from an infected family member. And media reports indicated today that a tour bus driver in Japan, who had transported tourists from Wuhan, also tested positive for the coronavirus.
David Heymann, an epidemiologist at the London School of Hygiene and Tropical Medicine, agrees that more cases of human-to-human transmission beyond China are likely. Health authorities can limit further transmission by isolating infected patients and closely following people they have had contact with.
But the effectiveness of these measures depends on the virus not being able to spread widely through the air. “You can generally keep an outbreak at very low levels unless it’s aerosolized,” Heymann says. In that case, contact-tracing and isolation are unlikely to stem spread.