It is still not known whether people vaccinated against Covid-19 can still transmit the coronavirus, the head of the EU's medicine regulator told MEPs on Tuesday.
There are also concerns about whether vaccines developed last year will be effective against new mutations of the coronavirus strain now circulating the globe.
But preliminary indications are that the vaccines in use so far in the European Union -- by BioNTech-Pfizer and Moderna -- "will continue to be effective against at least the UK variant", said Emer Cooke, executive director of the European Medicines Agency.
"I think the South African variant is more complicated, and we need additional work to determine the efficacy," she added.
On possible post-vaccine immunity, she said clinical trial data did not look at transmission "but it is something that we're asking the companies to look at".
The comments, provided via videolink to the European Parliament, came as member countries begin to restrict travel to curb the variants' propagation while hoping that vaccines might provide a solution.
Cooke also addressed delivery delays to the EU of doses from BioNTech-Pfizer and from AstraZeneca, which is poised to get authorisation by the end of this week.
While unable to shed light on the cause of the delay -- something she said fell to the European Commission, which signed the purchase contracts with the firms -- Cooke stressed the EMA "can work to help solve any type of manufacturing issues that do delay the supply."
This could include helping to open of extra manufacturing sites.
She demurred on what authorisation the EMA might give the AstraZeneca vaccine when asked about German media reports -- later denied by the German government -- that the jab could be less effective in people over 75.
Some reports have suggested that the EMA may only approve the AstraZeneca jab for the under 55s.
"I'm not going to prejudge any decision because this is a scientific and expert discussion that is ongoing. But it it is possible to conclude an authorisation that would focus on a particular age group or it's possible to conclude for a wider age group," she said.