San Francisco, US-based pharmaceutical major Moderna has said that it still expects to begin phase-3 clinical trial of its Covid-19 vaccine candidate in July after a report said that the late stage trial of the vaccine involving 30,000 participants got delayed due to changes in the study plan.

The trial was earlier scheduled to begin on July 9, according to investigators at the University of Illinois at Chicago.

Citing unnamed investigators, healthcare publication STAT News on Thursday reported that the trial has been delayed.

Moderna in a statement said that it still hopes to begin the trial in July.

"Moderna has previously disclosed that the Phase 3 trial of its Covid-19 vaccine candidate mRNA-1273 is expected to begin in July. The trial is still expected to begin in July and we expect to be the first to start a Phase 3 trial," the company said.

"We have worked closely with NIH/OWS (US National Institutes of Health / Office of Workplace Solutions) to align on the final protocol in order to begin the trial on time."

The Moderna vaccine candidate is an RNA-based vaccine designed to help the body produce antibodies that protect against Covid-19.

The World Health Organization (WHO) late last month said that the UK-based AstraZeneca is leading the race to develop an effective vaccine against Covid-19, while Moderan is not far behind.