The US Food and Drug Administration has urged that vaccines be granted according to the approved method, blaming officials who are trying to change the time between vaccination doses.
The experts advising the World Health Organization recommended against extending the interval between the two doses, a plan under study in the United Kingdom.
People familiar with the talks said that the European Union is negotiating with “Pfizer” and “Biontech” on a deal that could double its vaccine supplies, as leaders across the region face questions about the frequency of vaccinations against Covid-19.
Britain offered new support to the companies after Prime Minister Boris Johnson said the country would go into a third lockdown.
Germany extended its lockdown and tightened restrictions, while Italy expanded some restrictions to face the risk of many cases returning.