Cases with travel links to China, Italy, or Iran accounted for almost two-thirds of
the first reported COVID-19 cases from affected countries. Among cases with age information
available, most were among adults aged 18 years and older. Although there were many
clusters of household transmission among early cases, clusters in occupational or
community settings tended to be larger, supporting a possible role for physical distancing
to slow the progression of SARS-CoV-2 spread.
Source: www.thelancet.com