Former FDA commissioner Scott Gottlieb warned Wednesday that the latest CDC mask reversal could have a "negligible impact" on the spread of the Delta variant, telling CNBC that "we're not going to get enough bang for our buck" by instructing those who have already received the COVID-19 vaccine to continue to mask up indoors.

The updated CDC guidance urges vaccinated people to wear masks in indoor public settings as part of a nationwide effort to curb the Delta variant as it rears its head in cities across the U.S. 

BIDEN ADMINISTRATION SLAMMED OVER MASKS, VACCINE REVERSAL

While Gottlieb believes the recent spike in positive cases will likely dissipate in the coming weeks, he worries the CDC's guidance will have a counterproductive impact by further dissuading those already on the fence about the vaccine. 

Gottlieb did however emphasize that vaccinated people "need to be mindful" that they are still at risk of transmitting the virus, he told CNBC’s "Squawk Box."

Instead, he argued, the guidance should be focused on encouraging symptomatic individuals to get tested and take necessary safety precautions, he explained. 

"Much more prudent guidance to people would be that if you are vaccinated in a high prevalence area, in contact with [the] virus, you think you might have the virus because you have mild symptoms, be prudent, get tested, maybe wear a mask especially if you are around a vulnerable person," he said.

There is still significant pushback against universal masking, and not all jurisdictions are following the CDC's suit. The St. Louis County Council voted to end its recently implemented mask mandate Tuesday night, according to FOX 2. County Executive Sam Page, however, says the mandate is still in effect despite the vote. And the St. Louis city mask mandate, FOX 2 reported, is still in effect. 

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Even some Democratic governors who are known for their aggressive coronavirus mitigation measures are now slow to follow the CDC with universal masking. 

"Whether or not that should then translate to general guidance for the entire population, I don't think that that's the case," Gottlieb said. "I don't think we're going to get enough bang for our buck by telling vaccinated people that they have to wear masks at all times to make it worth our while."