The race to develop a coronavirus vaccine is moving forward rapidly, and some drugmakers have taken an unusual step to rapidly deploy their respective vaccines the moment the Food and Drug Administration gives the green light. Moderna (MRNA 1.90%) is the latest drugmaker to begin manufacturing millions of doses of its still-experimental vaccine, mRNA-1273, at risk.

During a recent conference call to discuss encouraging phase 1 trial results for mRNA-1273, CEO Stephane Bancel sketched out a plan to produce enough doses to vaccinate everybody in the U.S. In fact, the company thinks it can produce between 500 million and 1 billion doses annually. At the moment, Moderna and its manufacturing partners are producing doses of mRNA-1273 at three sites for the U.S. market.

Vials labeled as containing cronavirus vaccine and a stack of cash.

Image source: Getty Images.

During a phase 1 clinical trial, all 45 patients had antibodies in their bloodstream produced in response to mRNA-1273. But the immune system produces lots of different antibodies when it encounters anything foreign, so unfortunately it's hard to draw any meaningful conclusions from the results.

Volunteers vaccinated with mRNA-1273 produced high levels of some antibodies also seen in patients that have recovered from COVID-19. But we still have no idea whether or not high concentrations of those antibodies will effectively prevent SARS-CoV-2 from spreading.

By the end of July, Moderna plans to begin a 30,000-patient phase 3 study with mRNA-1273 that was previously scheduled to begin on July 9. The pivotal study was delayed because the company was late to submit final protocol changes to the FDA. The delay puts mRNA-1273 behind AZD1222 from AstraZeneca (AZN 2.68%), another coronavirus vaccine candidate that began a 5,000-patient phase 3 trial in Brazil at the end of June.