Scott Gottlieb, former FDA commissioner

Adam Jeffery | CNBC

The Centers for Disease Control and Prevention do not have sufficient resources to properly track “breakthrough cases” of Covid-19, said Dr. Scott Gottlieb across from CNBC’s Squawk Box on Wednesday.

The CDC stopped tracking every groundbreaking case in the US on May 1, focusing only on those leading to hospitalization or death, a move that doctors and scientists are increasingly criticizing.

“They don’t have good real-time reporting,” said Gottlieb. “We have to fix this, and it can be fixed. I mean, we can properly resource them and build better skills there.”

With the rise in cases in the US and new research showing that fully vaccinated individuals can transmit the virus as asymptomatic carriers, the scientific community is increasingly urging the agency to pursue any breakthrough case when fully vaccinated individuals test positive for Covid become.

As of July 19, more than 5,900 fully vaccinated Americans with breakthrough Covid infections have either died or been hospitalized, according to the latest data from the CDC. The website also notes that 1,821 of these cases were either “asymptomatic or unrelated to Covid-19”.

While none of the vaccines are 100% effective, they have shown strong results in protecting against serious illness or death from the virus, health officials say. According to the CDC and the World Health Organization, the vast majority of breakthrough infections are generally mild or asymptomatic.

People who are vaccinated and exposed to the Delta variant are seven times less likely to develop symptoms when infected than unvaccinated people, and 20 times less likely to experience hospitalization or death than someone who is not vaccinated, said CDC Director Dr. Rochelle Walensky in a briefing on Tuesday.

Before the delta variant dominated the US, the alpha variant first found in the UK accounted for the majority of cases. People infected with the alpha strain were not a major source of transmission, unlike Delta, which was a driving factor in the CDC’s decision to reverse their position on masks in areas with low vaccination rates where Covid cases are on the rise.

“We thought it was important that people understand that they have the potential to transmit viruses to others,” said Walensky.

There is mixed data on the effectiveness of vaccines against the Delta strain, but if mRNA vaccines are generally 90 to 95% effective then someone who is fully vaccinated and exposed to the Delta strain will have a 1-in 10 or 1 in 20 chance of getting a breakthrough infection.

“This is why in areas with significant or high transmission, even if you are vaccinated, we say that we think it is important to wear a mask in those environments,” Walensky said.

People infected with the Delta variant carry up to 1,000 times more virus in their nasal passages than other strains, which leads to higher transmittability. New CDC data suggests that vaccinated people can carry the same amount of virus as unvaccinated people.

“The breakthrough infections, rare as they are, have the potential to spread with the same capacity as an unvaccinated person,” Walensky said.

Breakthrough asymptomatic infections aren’t the only thing the CDC doesn’t have real-time data on, Gottlieb also said the agency also doesn’t have the resources to properly track flu infections or flu deaths each year.

“You actually derive it from a model,” said Gottlieb. “So the confidence interval is very wide.”

Gottlieb expects the CDC to improve the tracking of the Delta variant in the coming months.

“They will do a very good analysis of this delta wave, who will be infected and how likely in about four months, maybe a little longer,” he said.