The leaders will not be asked to vote on the measure, already provisionally applied, at Thursday's summit, and most would back it if it helps pressure AstraZeneca to boost its deliveries.

BRUSSELS: The looming third wave of coronavirus infections and Europe's struggle to mount a vaccination drive will dominate Thursday's EU video summit, despite a welcome guest appearance by Joe Biden.

The new US president will address the 27 EU leaders by video link in the evening as Washington and Brussels put on a show of mending ties after the dramatic diplomatic battles of the Donald Trump years.

But his intervention will only be a brief respite from the main matter at hand: How to outpace the resurgent epidemic when drug deliveries came up short and vaccination campaigns started slowly?

Host Charles Michel, the president of the leaders' European Council, had hoped to hold a substantive face-to-face summit, but was forced to accept a stripped down video conference as EU members reinstated lockdown measures.

The Europeans are angry that UK-based pharma giant AstraZeneca has failed to meet its vaccine delivery promises to the EU while ensuring smoother supplies to former member Britain.

But they are also squabbling among themselves over how to share the vaccines they have received, and not all are happy with the European Commission's threat to block some vaccine exports.

EU chief Ursula von der Leyen's executive updated its month-old control mechanism on Wednesday, giving the bloc more power to block vaccine shipments to countries like Britain that produce jabs but do not export them.

The leaders will not be asked to vote on the measure, already provisionally applied, at Thursday's summit, and most would back it if it helps pressure AstraZeneca to boost its deliveries.

But some -- like UK neighbour Ireland, and vaccine producers Belgium and the Netherlands -- are wary of any move to block exports from operations like Pfizer/BioNTech, which supplies both the EU and UK.

If the pharmaceutical industry's global supply chains are disrupted, many countries could lose out, as both British Prime Minister Boris Johnson's government and von der Leyen's commission accepted.