No European Union country has a bigger stock of AstraZeneca (AZ) vaccines or has used a smaller percentage of its stock than Italy.
Rome, with European Commission permission, stopped a shipment of 250,000 of the Oxford University jabs leaving the EU for Australia.
The ban was a rebuke to the British-Swedish pharmaceutical firm, which Brussels accuses of breaking its contractual obligations, which AZ denies.
In January it cut supplies to the EU in the first quarter to 40 million doses from the 90 million in the deal, and said it would cut deliveries by another 50 per cent in the second quarter.
The EU has lagged far behind the UK, US and Israel in rollout, which it blames on supply shortfalls. Italian prime minister Mario Draghi aims to use AZ to speed up vaccinations as his country gears to face a third wave.
He is expected to lift age restrictions and follow Britain's lead in having a longer gap between first and second jabs to increase the number having at least one shot. But a new YouGov survey of 1,029 Italians found that almost a quarter (23 per cent) would refuse the AZ jab and demand an alternative.
While Italy blocked the shipment to Australia, it had the largest reserve of that company's doses in the EU. It also had the third largest total stock of vaccines, which include the Pfizer and Moderna, behind France and Germany.
Italy has more than 1.5m AZ vaccines, the European Centre for Disease Prevention and Control said. The third most populous EU country behind Germany and France had used just 322,801 of its jabs - 21.3 per cent, as of Friday. It is a lower percentage than every other EU country except Malta, which has not received any AZ vaccines at all.
Germany has 1.4m doses of AZ and has dished out 466,596 or 32 per cent of its stock. France has just over 1.1 million AZ doses and has administered 275,529, 24 per cent. Spain has administered 47 per cent (382,962) out of its 808,600 doses of the Oxford inoculation.
Belgium is the closest to Italy's low rate, doling out just 21.7 per cent of its 201,600 AZ jabs. Italy still performs poorly in the EU when it comes to the percentage of its total vaccine stock of 6.4 million jabs.
Rome has administered 67.6 per cent, 4.3 million doses, of its stock, which lags behind most of the EU, including Spain, Lithuania, Latvia, Poland, Portugal and Romania. Only Bulgaria, Croatia, Hungary, Luxembourg and the Netherlands have used a lower percentage.
In Italy, some 3.5 million people out of the 60 million population have received at least one dose. Italy's new government wants to speed up the administration of AZ and other doses by drafting in doctors and nurses from the Italian armed forces and the widely-respected Civil Protection Agency, which deals with natural disasters.