The cause of several pneumonia cases in the Chinese city of Wuhan remains a mystery, as the number of infected people continues to grow, health authorities reported.
Seven of the sick are listed as critically ill, down from 11 on Friday. The number of close contacts of cases under medical observation has risen to 163.
Sunday’s statement, the third from the Wuhan Municipal Health Commission about the incident, is the first to give information about when people became infected. The first person known to have become ill began to show symptoms on Dec. 12 and the last date of symptom onset among the sick was Dec. 29, the statement said.