There’s no need for Covid booster doses right now, the dean of Brown University’s School of Public Health said Friday, as highly transmissible, new variants test the protections of the available vaccines.

“Let me tell you where we are: the data is very clear, if you’ve gotten your two shots of Moderna  or Pfizer  or single shot of J&J, you have a very high level of protection against all variants, including delta,” said Dr. Ashish Jha. “I have not seen any evidence, so far, that anybody needs a third shot.” 

Jha’s comments come after Pfizer and BioNTech announced Thursday that they are developing a Covid-19 booster shot intended to target the delta variant. Company officials say another shot may be needed because immunity from the vaccine appears to wane over time. 

On CNBC’s “The News with Shepard Smith,” Jha underscored the importance of waiting for the data when it comes to a booster shot. 

“If that evidence emerges, and obviously we’re going to want to take that into consideration, in my mind, I think there’s little likelihood that we’re going to need third shots for most people,” Jha said. 

The Centers for Disease Control and Prevention and the Food and Drug Administration issued a joint statement that said Americans who are fully vaccinated do not need a booster shot. 

“Americans who have been fully vaccinated do not need a booster shot at this time. FDA, CDC, and [the National Institutes of Health] are engaged in a science-based, rigorous process to consider whether or when a booster might be necessary,” read a joint statement released Thursday evening.