Hong Kong and Macau suspended the use of Pfizer/BioNTech´s coronavirus vaccine on Wednesday after being informed of a packaging problem affecting one batch of vials, while stressing they did not believe there was a safety risk.
The stoppage is the latest blow in efforts to role out mass vaccination programmes against a deadly virus that has killed more than 2.7 million people around the world and hammered the global economy.
"For the sake of precaution, the current vaccination must be suspended during the period of investigation," Hong Kong´s government said in a statement.
Both Chinese cities said their decision came after they were contacted about the issue by Fosun, the Chinese pharmaceutical company that is distributing the Pfizer/BioNTech vaccine in China.
Vials with the lot number 210102 were found to have defective packaging, authorities said.
The statements from Hong Kong and Macau did not give any details on how the packaging was defective but both said they did not believe there were any safety issues.
Authorities said they decided to act out of an abundance of caution until their investigation is concluded.
Some Hong Kongers took to social media to say their appointments that day had been cancelled and that some vaccination centres were closed.
Alexander the Great's bronze portrait is discovered in Denmark
Moscow, Washington boost military expenditure to reach $109 and $916 billion, respectively
Welsh journalist, presenter leaves BBC after 40 years of service
African-American commentator is not liked by many people but adored by others
Indian Prime Minister accused for hateful comments against Muslims
US President is observing Earth Day with special announcement