TAMPA, Fla. -- Russia's announcement that its health ministry approved the world's first coronavirus vaccine was met with concerns from health experts. 

"If you actually look at the news they put out there, they actually haven't developed a vaccine. We have vaccines already in phase three trials," said Dr. Michael Teng, an associate professor of the University of South Florida's internal medicine department.

Among the concerns brought up by Dr. Teng and others is the limited testing the Russian vaccine, known as "Sputnik V", has undergone on just dozens of people.

In the United States, 30,000 participants are required to take part in vaccine testing before it's approved. 

"The trials are not only to see efficacy, to see how well it works in the population. They're also to see, maybe there's a minor component of safety that they didn't see in those first few studies where they did a small number of people," said Teng."

Larger scale trials on the Russian vaccine are expected to begin this week.

Another issue is that Russia isn't releasing evidence to back up claims of efficacy. Dr. Teng said even with vaccines still under development in the United States and elsewhere, preliminary information has been released.

"They've actually gone ahead and shown some of those data. Some of those studies have been, not necessarily published yet, but they actually have papers out there where people can actually look at the data," said Teng. "The Russians have not shown any of the data, and really, these trials that they've done are basically safety trials."

Dtr. Teng said a concern is that a rushed vaccine turns out to be ineffective, eroding in the public's confidence in other vaccines under development. Teng said it's unlikely the FDA would approve this vaccine for use in the U.S. unless Russia releases its data or it was involved in an FDA-approved clinical trial.