The Gaithersburg, Md., company is struggling to source some of the raw materials it needs for the vaccine, the company said, according to a Reuters report.
A European Union official involved in negotiations told Reuters that the company was delaying negotiations.
The EU earlier this year had been planning to a sign a deal for at least 100 million doses of Novavax's vaccine, with an option for another 100 million doses.
The EU official said that the company has postponed signing a deal for weeks, citing legal issues in meetings. "They are slowing down the process of finishing the contract," the official who attended the meetings told Reuters.
Novavax shares were down 8.7% in afternoon trading at last check.
A company spokesperson told Reuters that the company is working through some pandemic-related raw-materials-supply shortages. The spokesperson did not provide further details.
Beyond Novavax's commitment to provide up to 200 million doses to the EU, earlier this year the company said it would supply 1.1 billion doses of its COVID-19 vaccine candidate to Gavi, an international organization that provides vaccines in poorer countries.
Earlier this month, Novavax reported positive Phase 3 results from its U.K. trial of a vaccine candidate against COVID-19.
The company said the vaccine candidate had a final efficacy of 86.3% against the fast-spreading U.K. variant of COVID-19. The U.K. study enrolled more than 15,000 participants.
The vaccine candidate had even higher effectiveness against the original COVID-19, with 96.4% efficacy.