Shares of Novavax Inc fell 20% after a report from Politico said the company faces significant hurdles in proving it can manufacture its experimental COVID-19 vaccine that meets regulators' quality standards, resulting in production delays.

The methods Novavax used to test the purity of its vaccine have fallen short of U.S. regulators' standards, according to the Politico report, citing people familiar with the matter.

Novavax in a statement said it was confident in its ability to deliver its high-quality vaccine.

"We underscore our ongoing commitment to the stringent standards of production and manufacturing for our recombinant nanoparticle protein-based COVID-19 vaccine candidate with Matrix-M adjuvant," the company said.

The company said it has filed for regulatory authorization for its shot in India, Indonesia and the Philippines and reiterated that it expects to file for emergency use authorization in the United States before the end of 2021.

(Reporting by Ankur Banerjee in Bengaluru; Editing by Sriraj Kalluvila) ((;; Mobile - +919008417318; Twitter: @AnkurBanerjee17;))