How Georgia And CDC Don't Agree On Vaccine Math
Throughout Georgia’s fight against COVID-19, Gov. Brian Kemp has taken issue with CDC statistics that paint a less positive picture for Georgia than the state’s own statistics. Now, a new data page from the Centers for Disease Control and Prevention might clear up at least one area of disagreement.
The new page tracks how much vaccine comes into a state and how those shipments are shared across the different kinds of providers. Those providers range from chain pharmacies, such as Walgreen’s or CVS, to Georgia public health clinics that ultimately report to the state Department of Public Health.
The page also tracks how much vaccine is administered in a state.
Those two streams of information — shipments into a state and vaccinations performed in a state — set up a math problem you may remember from grade school. But it’s in this calculation where the Georgia DPH and the CDC part ways.
It’s all about a division problem. Visualize it like a fraction.
First, take the total number of vaccine doses administered in Georgia. That's the top number, the numerator.
Then, take the total number of doses shipped to Georgia. That's the bottom number, the denominator.
Now divide the numerator by the denominator, take the extra step of multiplying the result by 100 and you have the percentage of Georgia’s vaccine supply that has successfully found a person’s arm.
The problem, first sussed out by Georgia COVID-19 watcher and science communicator Amber Schmidtke, is that the DPH and the CDC don’t agree on what the denominator is in that math problem.
As of Friday, the CDC said Georgia has received over half a million more doses than what DPH accounts for on its vaccine dashboard. To compound the problem, the state says it has administered over half a million more doses than the CDC has in its accounting.
The result is an over 1 million dose discrepancy. Depending on if you believe DPH, Georgia has either dosed out 80% of what has been shipped to it or, if you believe the CDC, 68%.
So why this gap?
For the denominator, Schmidtke said the DPH is apparently not counting the doses shipped by the federal government to pharmacies and maybe not even those shipped to the mass vaccination sites run by Georgia Emergency Management Agency (GEMA) when it calculates the percentage of shipped vaccine that has been administered.
Schmidtke said that may just be because the federal government isn’t keeping the state on top of what it is sending to non-state providers in the state.
“They can only track what they know of,” Schmidtke said of the DPH. “So if they're only aware of the doses that have been delivered to DPH, then that is the only denominator they have.”
As for the numerator: The reason why the two agencies' numbers are so different for what has been administered in the state is less clear.
Regardless, Schmidtke said that given the federal government is the source for all vaccines, and given the data discrepancy, DPH is likely not the best source of information for data around Georgia’s vaccine effort.
“I don't think that DPH is in a position — or the state in general is in a position — to grade their own performance,” Schmidtke said. “They don't get to sort of make up a new math. It's not right to look at all doses administered from all providers compared to just the doses that the state controls.”
Georgia DPH was asked about why its calculation differs from the calculation by the CDC for this story. The agency has not yet responded.