No widespread nucleic acid testing was conducted on the public in the city.
Zhang said, "Our refined management measures help us detect a case among crowds in the city, identify those possibly infected before they develop symptoms, and contain the virus.
"These factors are particularly significant, as COVID-19 cases that emerge from time to time will become a new normal."
More than 100 million COVID-19 cases have been reported worldwide. Local infections in China last month totaled 2,016, the most since March last year.
Li Qiang, Shanghai's Party secretary, said the pandemic situation is still complicated and everyone must constantly remain vigilant, detect any shortcomings and check for loopholes.