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Fauci Curious to See Secret of Covid Shot’s Success Unlocked

Dec. 14, 2020, 8:56 PM

Forthcoming data on Johnson & Johnson and AstraZeneca Plc’s Covid-19 vaccine candidates will shed light on the one question still unanswered by the Pfizer and Moderna vaccine frontrunners—what gives the shot its fighting power.

Pfizer Inc.-BioNTech SE and Moderna Inc.'s vaccines will be the first to use the messenger RNA platform outside of a clinical trial, and the 95% success rate far exceeded expectations—which bodes well for other diseases like cancer. Moderna’s vaccine should be recommended for use by a Food and Drug Administration advisory panel Dec. 17 with an emergency use authorization quickly following, top infectious disease expert Anthony Fauci predicted in an exclusive interview with Bloomberg Law.

Messenger RNA instructs cells in the body to make proteins that fight off or prevent disease. However, it is fragile and must reach cells before the body breaks it down. The Pfizer and Moderna coronavirus vaccines use a modified form of mRNA and coat it with fatty nanoparticles.

Moderna and Pfizer’s vaccine platforms are practically identical, said Fauci, director of the National Institute of Allergy and Infectious Diseases. The conformation of the spike protein, which is found on the surface of the SARS-Cov-2 virus that causes Covid-19, is nearly identical as well.

A couple factors could explain the success of these vaccines, Fauci said. One of them could be the vaccine platform itself. The other could be a technology developed by Barney Graham, deputy director of the NIAID Vaccine Research Center, to stabilize the spike protein that gives the coronavirus its crown-like feature before it infects immune cells, in order to produce the anitibodies needed to fight off the virus.

“So it could be not only the platform itself, which is highly adaptable to a successful outcome, but it’s actually the conformation of the spike protein,” Fauci said.

Vaccines that are still in the pipeline from AstraZeneca and Johnson & Johnson could help unlock this mystery. AstraZeneca uses a weakened version of the common cold called an adenovirus that contains the genetic material of the SARS-Cov-2 spike protein.

Johnson & Johnson is also making what’s called an adenovirus-based vaccine. “If we get the same results, then it’s likely the conformation of the spike as opposed to the particular platform. If the mRNA is the reason, we’ll find out soon enough,” Fauci said.

Moderna Awaits Review

The FDA‘s panel of outside scientific advisers will meet Dec. 17 to review Moderna‘s request for an emergency use authorization for its Covid-19 vaccine. The committee met one week earlier to review Pfizer and BioNTech’s vaccine, which the FDA authorized the following night. If authorized, Moderna’s vaccine will be added to initial doses shipped out this week for essential health workers and long-term care facility residents.

“I don’t want to get ahead of the FDA, but I would be surprised if we didn’t see the same result regarding the FDA and Pfizer compared to FDA and Moderna,” Fauci said. “The results are so similar and the platforms are essentially identical.

“By next week we believe we could be having a second vaccine,” Health and Human Services Secretary Alex M. Azar said Monday.

Federal officials anticipate a Moderna vaccine will likely be authorized this week and shipments for that vaccine will begin next week. “Our goal would be for the Moderna product to be available this time next week across the United States,” Gen. Gustave Perna, who heads the Operation Warp Speed vaccine distribution effort, told reporters Monday.

—With assistance from Jacquie Lee

To contact the reporter on this story: Jeannie Baumann in Washington at

To contact the editors responsible for this story: Fawn Johnson at; Andrew Childers at