The US is expected to back the use of the Pfizer/BioNTech vaccine for people aged 12 to 15 within a week. Europe's watchdog launched its review on Monday with a decision expected in June.
The European Commission president has announced that 70% of the adult population in the EU will receive at least one vaccine dose by July.
Authorities in the US and the EU have already started planning for such an eventuality.
The European Commission chief said the total doses EU countries will receive from Pfizer will now be 250 million in the second quarter of this year.
Hong Kong halts use of Pfizer vaccine, cites defective lids
The latest vaccine exports figures from the EU Commission come days after London and Brussels lobbed accusations of vaccine nationalism at each other.
The extra doses will be delivered in the next two weeks as the bloc faces sharp criticism over the slow rollout of vaccinations.
Sanofi is to produce as many as 12 million doses a month of the Johnson & Johnson vaccine once approved. It has also agreed to manufacture 125 million doses of the Pfizer/BioNTech jab.