The COVID-19 case in Shanghai that was reported on Wednesday was likely to have been infected by the recent imported cases or contaminated environments, said the municipal epidemic control authority on Friday.

The leader group of the Shanghai municipal COVID-19 prevention and control efforts said an epidemiological survey showed that the infected person who works in a hospital in Songjiang district had not made contact with domestic cases and their close contacts in the past 14 days, had not traveled to high- or middle-risk areas, and was not exposed to cold-chain logistics.

The Wednesday case was confirmed to be infected with the COVID-19 Delta variant, and the municipal center for disease control and prevention said that gene sequencing of the case was found to be related to previous imported COVID-19 cases who had been quarantined in the hospital where the female case works.

State and Shanghai experts concluded that the new infection case was due to a lapse in personal protection measures.