WASHINGTON - US biotech firm Moderna said on Thursday it expects to begin a phase-3 study of its COVID-19 vaccine candidate in July.

Moderna has finalized the phase-3 study protocol based on feedback from the US Food and Drug Administration. The randomized, 1:1 placebo-controlled trial is expected to include approximately 30,000 participants enrolled in the United States and is expected to be conducted in collaboration with the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, according to a release of the company.

With the phase-3 dose being finalized at 100 mcg, Moderna remains on track to be able to deliver approximately 500 million doses per year, and possibly up to 1 billion doses per year beginning in 2021, said the release.

"We look forward to beginning our Phase 3 study of mRNA-1273 with some 30,000 participants in July," said Moderna Chief Medical Officer Tal Zaks.

"Moderna is committed to advancing the clinical development of mRNA-1273 as safely and quickly as possible to demonstrate our vaccine's ability to significantly reduce the risk of COVID-19 disease," he said.