Shares of Moderna Inc (NASDAQ: MRNA), a frontrunner in the race for a coronavirus vaccine, tumbled Thursday afternoon after a STAT News report suggested there could be a delay in the initiation of a late-stage study.

Moderna's July Start In Doubt: Moderna's Phase 3 trial of mRNA-1273, which was set to start next week, is likely to be delayed due to changes the Boston, Massachusetts-based company is making to the trial protocol, STAT News reported, citing investigators who spoke on the condition of anonymity.

A clinical trial protocol is a document outlining all details of study, including objectives, design, methodology, statistical considerations and organization of the trial that would ensure safety of the participants and integrity of data.

Moderna had guided to a July start for a Phase 3 study with about 30,000 participants.

Following the STAT News report, a statement posted on Moderna's Twitter handle suggested the Phase 3 trial initiation timeline is intact.

In mid-June, Moderna CEO Stephane Bancel told Bloomberg that the company plans to have efficacy data as early as Thanksgiving if all goes to plan.

The company announced early data from the NIAID-sponsored Phase 1 trial in mid-May and is also running a company-led Phase 2 trial.

Pfizer's Program Picks Up Pace: Large-cap pharma Pfizer Inc. (NYSE: PFE), which is also developing an RNA vaccine for SARS-CoV-2 in partnership with Germany's BioNTech SE – ADR (NASDAQ: BNTX), reported last week with positive preliminary data from the Phase 1/2 trial of BNT162b1, the most advanced of four investigational vaccine candidates from the BNT162 RNA-based vaccine program, which is dubbed Project Lightspeed.

The companies said they plan to start a large, global Phase 2b/3 safety and efficacy study involving up to 30,000 healthy participants as early as this month, suggesting their program is running neck-to-neck with Pfizer.

See also: Attention Biotech Investors: Mark Your Calendar For These July PDUFA Dates

Oxford University, AstraZeneca Running Late-Stage Program: The Oxford University, which is partnering with AstraZeneca plc (NYSE: AZN) on developing a novel coronavirus vaccine dubbed ChAdOx1 nCoV-19, initiated a Phase 3 study in June, with enrollment ongoing in Brazil and South Africa.

ChAdOx1 nCoV-19 is made from a weakened version of a common cold virus that causes infections in chimpanzees and has been genetically changed so that it is impossible for it to grow in humans.

If results from the trial prove to be positive, Oxford University could have a vaccine by the end of the year.

Chinese Contenders In The Fray: China's CanSino Biologics' adenovirus type 5 vectored COVID-19 vaccine, dubbed Ad5-nCoV, produced virus-specific antibodies and T cells in 14 days with a single dose in a Phase 1 trial that evaluated 108 participants. A Phase 2 trial is ongoing in Wuhan, China, the epicenter of the crisis.

State-run Sinopharm reported in June the inactivated COVID-19 vaccine developed by its subsidiary produced a strong neutralizing antibody response in a Phase 1/2 study.

Sinovac also released in June preliminary results from the Phase 2 part of the Phase 1/2 study that showed its vaccine, dubbed CoronVac, induced neutralizing antibodies in over 90% of the 600 trial participants.

All these firms are imminently planning pivotal trials that could support regulatory clearance.

About 18 vaccine candidates are in clinics and 129 more in preclinical evaluation, according to the World Health Organization.

Related Link: Applied DNA Analyst Says Coronavirus Testing, Vaccine Work Could Drive Major Upside

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