Might Johnson & Johnson (JNJ 0.12%) soon vault to the top of the coronavirus stock list?

It's conceivable, as an entry on the government's list of clinical trials reveals that the company's Janssen Vaccines subsidiary is about to launch a relatively large-scale, phase 3 study of its Ad26.COV2-S vaccine candidate. The estimated start date is Sept. 5, with both the primary and completion date anticipated for March 10, 2023.

All told, the Johnson & Johnson/Janssen study aims to involve roughly 60,000 participants with moderate to severe COVID-19, age 18 and older. It will be a randomized, double-blind, and placebo-controlled trial.

Coronavirus container receiving swab.

Image source: Getty Images.

That 60,000 figure is double the typical late-stage participant number; front-runners Moderna, with its mRNA-1273 candidate, and Pfizer and BioNTech with BNT162b2 have both targeted approximately, or at most, 30,000 patients in their respective trials.

Although other biotechs and pharmaceutical companies are in more advanced testing stages of their coronavirus vaccine candidates, Johnson & Johnson has a particular advantage that might ultimately pull it ahead of the pack.

In preclinical testing on primates, Ad26.COV2-S produced high levels of antibodies to combat infection with only a single dose; other vaccine candidates further along in their development require two doses to produce a similar response.

The coronavirus "race" is one of the most closely watched developments in the healthcare world just now. The outbreak is still very much a threat to global health, and no vaccine has yet been approved for use by any major regulator.

In late afternoon trading on Thursday, Johnson & Johnson's stock was up by 0.6%, outpacing the 0.4% rise of the S&P 500 index.