News that Pfizer's coronavirus vaccine strongly protects people against infection is good news for other vaccines being developed against the pandemic, Dr. Anthony Fauci said today.

Pfizer said its candidate vaccine was more than 90% effective in preventing infection in volunteers. It uses a never-before-approved technology called messenger RNA, or mRNA, to produce an immune response in people who are vaccinated.

"This shows that the mRNA platform actually does work. And there's another vaccine candidate, Moderna, that's using the same platform," Fauci told CNN in a telephone interview.

Fauci's National Institute of Allergy and Infectious Diseases is working with Moderna and other companies to test their experimental vaccines.

The US federal government has invested $1.95 billion in Pfizer and BioNTech's vaccine but is not directly working to help its development.

The mRNA vaccine approach uses genetic material called mRNA to trick cells into producing bits of protein that look like pieces of the virus. The immune system learns to recognize and attack those bits and, in theory, would react fast to any actual infection.

"Really encouraged to see this exciting announcement. Assuming it's supported by the data then this not only represents a potential breakthrough for Pfizer/BioNTech, but also for vaccines in general," vaccine expert Robin Shattock, whose team at Imperial College London is working on an mRNA vaccine against coronavirus, said in a statement.

"It also demonstrates the speed and utility of RNA vaccines technology," Shattock added.

"This announcement certainly gives a boost to our own self-amplifying RNA vaccine program. Not yet the end game, but hopefully the beginning of global efforts to control this pandemic. A significant light at the end of the tunnel."

There's a second reason the Pfizer results are good news for other vaccines. They show that using spike protein as a target was the right call, Fauci said.

"The other good thing about it is that an actual immune response to the spike protein is a protective response," Fauci said.

The virus has a structure called the spike protein to grapple the cells it attacks. The mRNA vaccines make the body produce little copies of just that structure.

"Remember -- people were not sure that if you made an immune response against the spike protein that that's the best and most appropriate target for an actual vaccine," Fauci added.

"The good news is that this is the spike protein target and virtually every one of the other vaccines that are being tested also use the spike protein as a target, whether it's expressed in mRNA or it's a soluble protein. The spike protein is used in all of them, which bodes well for all the other vaccines."

Four coronavirus vaccines are in advanced, Phase 3 trials in the US now. They are made by Pfizer, as well as Moderna, Johnson & Johnson and AstraZeneca. Plus Maryland-based Novavax is expected to start a US-based Phase 3 trial later this month. It has a trial underway in Britain.

Pfizer got such a quick indication that its coronavirus vaccine is highly protective against infection in part because the pandemic is so bad, Fauci said.

The data was revealed as part of what's called an interim analysis. These are pre-planned peeks at the data.

In this case, Pfizer had planned to have a look as soon as 62 people in its 44,000 volunteer trial developed Covid-19 infections. But before the company could even finish discussing its plans with the U.S. Food and Drug Administration, it said, 94 people had become infected within a week of getting their second dose of either vaccine or placebo.

Pfizer's Data and Safety Monitoring Board -- an outside team of experts who watch the trial with a neutral eye -- unblinded the data and saw that more than 90% of those cases were in people who had gotten placebo, or dummy shots.

That's a reflection of both the large size of Pfizer's trial and the rate of infection across the United States, which just passed its 10 millionth diagnosed case, Fauci said.

"An answer depends on the size of the trial and how many infections there are in the community," he said. It's not clear if all the cases used by Pfizer for its interim analysis were in the United States. The company is also testing the vaccine in Brazil, South Africa, Japan and other countries.

"This was a trial that was geared to 44,000 people and we are in the middle of a major surge right now. Those two things together make it much more likely that you'll get an answer quickly, which is what happened -- we got an answer quickly," Fauci added.

Fauci said he expects Pfizer to apply to the FDA for emergency use authorization within about a week and a half. That will make it two months since volunteers got their second doses of vaccine. The FDA has asked vaccine makers for two months of safety data before they apply for authorization.