The Centers of Disease Control and Prevention report that 77.6% of eligible Space Coast residents have received at least one dose of a vaccine. The Florida Department of Health puts the number at 70%.
Which is it?
You’d think that would be an easy answer. But it’s not and it comes down to, in part, what goes into that data set and how it’s calculated.
So which is more accurate? The CDC or FDOH?
That depends who you ask.
We all prefer information that’s clear and comprehensive so when two different agencies seem to disagree over the same data point, it can create “undue confusion and frustration,” said Jason Salemi, associate professor of epidemiology at the University of South Florida.
“A clear explanation of each data metric is vital so that people can understand how and why seemingly identical metrics may actually be different.”
The CDC reports that as of Feb. 16, there were 448,030 people in Brevard County aged five and older who had received at least one dose of a vaccine. However, the FDOH only reported that 407,221 residents had received at least one dose of a vaccine as of Feb. 10.
What’s behind the difference?
For starters, the CDC figures include federal entities like the Department of Defense, which means it includes military personnel assigned to Florida bases, said CDC press officer Scott Pauley.
That can complicate things.
Since FDOH doesn’t count federal entities like service people, that can lead to differences.
So if, “Let’s say you’re a DOD and you’re stationed in Tallahassee and you get the shot but you’re a resident of the state of Georgia, you might be counted in Georgia as opposed to Florida.”
Another difference between the two agencies: the CDC derives the vaccination rate using 2019 Census data whereas FDOH uses 2021 population estimates from Florida CHARTS.
According to Pauley, the CDC also tracks vaccines given rather than people who get vaccinated. When a vaccine is given, it is recorded and given a recipient identifier and a vaccine event identifier. The CDC gets counts from different entities like pharmacies, state health departments and federal entities and relies on those entities to make sure doses and records aren’t double counted.
But Pauley added that there can be problems when for example, someone gets vaccinated somewhere that sends their data to an immunization information system, like Florida SHOTS that the FDOH uses, but then gets a second dose somewhere that does not use an immunization information system. The result: that individual’s second dose may not be linked to their first dose and the CDC may end up misclassifying it as a first dose.
Pauley said that it if there are any duplications or errors, “we try to review those and correct that data back down to get the most accurate count.”
At an emergency management meeting, John Davis, community health nursing director at FDOH-Brevard, emphasized that what matters most is that you’re consistent with the data you use, which he said FDOH-Brevard has been.
“The numbers that we are given have remained consistent, I mean we’re using the same database,” Davis said.
Salemi agreed that’s important.
“I do value that FDOH confirms a consistent approach has been used,” he said. “That is important because any changes we see in the metrics over time are more likely to be due to actual changes as opposed to artifacts in the data that result from changing definitions, methodologies, or data sources over time.”
“I don’t know that I would necessarily consider it a discrepancy between the two, its just that we’re counting the full breadth of the vaccination data. Whereas the Florida Department of Health might not have as much from the base or from the military agencies,” Pauley said.
According to Jay Wolfson, distinguished service professor of public health medicine and pharmacy at the University of South Florida in Tampa, if the difference between the two rates was larger, it may be an issue for the public. However, since “there is already so much distrust within the public of many reported measures by both state and the federal government, I don’t expect it is going to make much of a difference and can be ‘explained away’ by reporting nuances,” Wolfson said.
Though there may be discrepancies between CDC data and FDOH data, Salemi still believes that they can be trusted to provide a sense of how many people are vaccinated in Florida.
“I believe that we can absolutely trust the data. They are imperfect in every state and in every country but I do think they give us a very good snapshot of where we’re at and what we’re doing,” Salemi added.
Amira Sweilem is the data reporter at FLORIDA TODAY. Contact Sweilem at 386-406-5648 or asweilem@floridatoday.com.
