There were enough cases of an unknown pneumonia reported to Wuhan health authorities to trigger an investigation in early January. In the early stages of the epidemic, the number of cases was doubling approximately every seven and a half days.
Visa vya kutosha vya mchochota wa pafu visivyojulikana vilikuwa vimeripotiwa kwa mamlaka za afya Wuhan kusababisha uchunguzi mwanzo wa Januari.Katika hatua za mwanzo wa mlipuko, nambari za visa viliongezeka maradufu takriban kila siku saba na nusu.