The European Union drug agency said it may need four more weeks to approve its first coronavirus vaccine, even as authorities in the United States and Britain continue to aim for a green light before Christmas.

The European Medicines Agency plans to convene a meeting by December 29 to decide if there is enough safety and efficacy data about the vaccine developed by Pfizer and BioNTech for it to be approved. The regulator also said it could decide as early as January 12 whether to approve a rival shot by American pharmaceutical company Moderna Inc, which submitted its request to U.S. and European regulators this week.

If its vaccine is approved, Germany-based BioNTech said the shot’s use in Europe could begin before the end of 2020. Any approval granted by the European regulator will be conditional on companies submitting further information to confirm the vaccine’s benefits outweigh the risks.

The date now being eyed would be later than some European countries had hoped. Germany, which has given BioNTech 375 million euros in funding to develop the vaccine, has been preparing to start immunizing people from mid-December onward.