The European Union's drug agency is now allowing doctors to draw up to six doses from each vial of the Pfizer/BioNTech vaccine.
This is one more than the five originally approved by the European Medicines Agency (EMA) when it gave the go-ahead for the coronavirus jab on 21 December.
German health ministry spokesman Hanno Kautz said the practice, which is already permitted in the UK, would come into effect immediately, boosting available doses of the vaccine by 20%.
The move comes after European Commission President Ursula von der Leyen said the bloc had secured an extra 300 million doses of the Pfizer vaccine.
EU member states have also been offered the chance to buy an extra 300 million - bringing the total available to 600 million.
Ms Von der Leyen said 75 million of the extra doses would be available before July, with the rest delivered throughout 2021.
The bloc has six contracts for up to 2 billion doses, with Moderna, AstraZeneca, Sanofi-GSK, Janssen Pharmaceutica NV, Pfizer/BioNTech and CureVac.
This week, Moderna became the second COVID-19 vaccine approved by the EU following the one produced by Pfizer.
The EMA is still assessing the Oxford/AstraZeneca version with approval possible by the end of the month. The UK started administering it this week.
Vaccination programmes in the EU have started slowly, with some states blaming the Commission for a perceived failure to deliver the right number of doses.
It has defended its strategy, saying vaccinations have just started and large deliveries are foreseen around April.
Ms von der Leyen said: "We were faced with a situation where we had huge demand, but the production capacity had not kept pace with that as yet. Now, we have a positive step forward."
After reports some EU countries tried to secure separate deals with vaccine manufacturers, Ms von der Leyen made clear these would violate the agreement accepted by EU members.
"We have all agreed, legally binding, that there would be no parallel negotiations, no parallel contract," she said.
"So the framework we are all working in is a framework of 27. Together we are negotiating, together we are procuring and together we are bringing forward this vaccination process."