Dr. Scott Gottlieb warned that Covid-19 could force schools to pull out again this fall amid concerns over possible classroom outbreaks.

“Unfortunately, it’s possible, especially if you go into this school year without the kind of mitigation we introduced last year,” Gottlieb, the former FDA chief in the Trump administration, told CNBC’s The News with Shepard Smith “.

“We cannot expect fewer measures to be taken to contain infection in schools and the same outcome to keep infection at bay.”

The American Academy of Pediatrics found that children accounted for 15% of all new Covid cases last week. Gottlieb recommended Covid containment tools for schools such as masking, placing children in defined social groups, routine tests, and retrofitting air filter systems.

Gottlieb pointed out to host Shepard Smith that schools shouldn’t “take their foot off the break” if the goal is to stay open.

“This is a much more contagious variety, it could be a lot harder to control in school so the goal should be to keep schools open and try to keep these measures going until we see how it goes,” said Gottlieb.

Disclosure: Scott Gottlieb is a CNBC employee and a member of the board of directors of Pfizer, genetic testing startup Tempus, health technology company Aetion Inc., and biotechnology company Illumina. He is also co-chair of the Healthy Sail Panel of Norwegian Cruise Line Holdings and Royal Caribbean.