The approval procedure for a coronavirus vaccine in the European Union (EU) cannot go any quicker than it is being conducted, but a decision should arrive before December 29, European Medicines Agency (EMA) director Emer Cooke said in Amsterdam on Monday.
"We are working around the clock for the approval of the first Covid-19 vaccine," she told reporters.
However, she added that deadlines would be "constantly re-evaluated".
German Health Minister Jens Spahn has called for an acceleration of the process.
Vaccination started in US
The vaccine from Pfizer and BioNtech was first approved for use in Britain. The United States started its vaccination programme on Monday following emergency authorization.
EMA head Cooke stressed that there would be no compromise on safety.
Unlike the US and Britain, the EU does not grant emergency authorization for vaccines, meaning they must pass the usual tests.
