China has found harmless traces of the novel coronavirus in some Covid-19 inoculation sites potentially linked to vaccine liquid, its disease control centre said.
Samples taken from tables, walls, doorknobs and hallways of the sites tested positive for the virus but were not infectious, Chinese Center for Disease Control and Prevention (China CDC) said in a statement late on Sunday.
The traces had identical genome sequences as the strain found in used vaccine vials but were different from the strains currently spreading, China CDC said.
Inactivated vaccines contained relatively complete nucleic acid snippets of the virus and were not infectious, it added.
Inactivated vaccines from Sinopharm and Sinovac Biotech are being used in China's vaccination scheme.
Benjamin Cowling, an infectious disease expert from the University of Hong Kong, confirmed the possibility of contamination in the sites from vaccine liquid and said such virus traces were "nothing to worry about."
Staffers in contaminated vaccination sites had tested negative of the virus, China CDC said.