EU leaders threatened to block exports of AstraZeneca's coronavirus vaccine from the European Union after the company said it may only meet around half of its delivery schedule promises.  

EU leaders said that AstraZeneca's revised vaccine distribution plan was "unacceptable." The pharmaceutical company changed its distribution plan after it said that it may be experiencing significant shortfalls on its original delivery schedule.

AstraZeneca initially committed to delivering 100 million doses of its COVID-19 vaccine to EU member countries in the first quarter of this year. However, the company said that it will likely only be able to deliver around half that amount.

European commission president, Ursula von der Leyen, reportedly had a "heated call" with AstraZeneca's chief executive officer, Pascal Soriot, on Monday. Von der Leyen reportedly demanded that the company meet its contractual obligations.

"She made it clear that she expects AstraZeneca to deliver on the contractual arrangements foreseen in the advance purchasing agreement," an EU spokesperson said in response to questions regarding the call.

Von der Leyen reminded the company that the EU had paid them upfront to ensure that production is ramped up even before the vaccine had received a market authorization.

EU health commissioner, Stella Kyriakides, expressed her disappointment in the company in a televised statement Monday.

Kyriakides said that EU member states have requested that AstraZeneca submit a detailed plan of its vaccine deliveries and distribution. EU leaders and AstraZeneca executives are expected to hold another meeting on Wednesday to discuss the matter further.

EU member countries are significantly falling behind in terms of how much of the population they have vaccinated. In the UK, around 10 out of 100 residents have already been inoculated, while the EU has only administered about two out of every 100 residents.