A new Centers for Disease Control and Prevention study found health care workers who got the Pfizer or Moderna vaccines were 90% less likely to get COVID-19.

"The findings of this recent CDC study are actually huge," said Dr. Thomas Unnasch, a distinguished professor with the University of South Florida and co-director of its Center for Global Health and Infectious Disease Research. 

The study followed nearly 4,000 health care workers, first responders and other essential personnel after they received the mRNA formulas. Unnasch said the reason these results are so impressive is because that 90% efficacy rate refers to both symptomatic and asymptomatic cases.

"Back when they did the studies in the initial clinical trials on the mRNA vaccines, they really wanted to get these things out as quickly as possible. So, they looked at an endpoint of how good were the vaccines at preventing people from getting, you know, severe disease," said Unnasch. "But the one thing that we weren't really sure about was if you were vaccinated, could you still get infected and be asymptomatic and transmit to other people?"

BayCare Health System Executive Vice President and Chief Medical Officer Dr. Nishant Anand said the study's results provide some answers.

"They never were infected. And then, more importantly, they would never go on to infect other individuals — extremely significant because that whole question has been lingering out there. We've been wondering, we've been worrying about those folks. Again, even though they were vaccinated, would they still inadvertently transfer it to a patient or to a loved one? So, that question is actually starting to be answered."

Anand notes this is an interim analysis, which means the study has yet to be completed.