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Registered nurse Ana Pereira prepares a Pfizer/BioNTech COVID-19 vaccine at the Gimbel Gymnasium on April 21.

Credit: Chase Sutton

The Centers for Disease Control and Prevention reported this week that 95% of adults in Pennsylvania had received at least one dose of the COVID-19 vaccine — but the real number of vaccinated adults is lower.

A Pennsylvania data cleanup on July 7 found that the CDC has consistently overcounted the number of adults who have received their first doses and slightly undercounted the number of fully vaccinated adults, The Philadelphia Inquirer reported. While state and city officials continue to cite CDC data, acting Pennsylvania Health Secretary Alison Beam told the Inquirer this week that the CDC's data is inaccurate and that Pennsylvania and Philadelphia health departments are more accurate representations of COVID-19 vaccination rates.

The official numbers provided by the CDC have multiple inaccuracies due to difficulties with tracking vaccinations, according to the Inquirer. In July, the number of first doses was overcounted by more than half a million and the number of fully vaccinated people was undercounted by about 64,000. 

While federal data from the CDC is an inaccurate representation of vaccination rates, there are still issues with state and city data. The vaccine statistics published by Philadelphia and Pennsylvania undercount the number of vaccinations because they don’t include out-of-state vaccinations or vaccinations by federal providers, which are included in the CDC data, according to the Inquirer.

The CDC reports that 80% of all Pennsylvanians, including those under five who aren’t yet eligible, have had at least one dose of the COVID-19 vaccine. However, numbers released by the Philadelphia Department of Public Health indicate that only 66% of all Pennsylvanians have received one dose of the vaccine. The real number of adults who have received at least one COVID-19 vaccine likely falls between that range, the Inquirer reported. 

The CDC reported the 95% vaccination rate for Pennsylvania in its state-by-state map, which compiles vaccination data for every state in the United States. The information presented in the map is regularly cited by news outlets and health officials, including the Pennsylvania Department of Health in its daily news press releases.

On Friday, a CDC spokesperson acknowledged the difficulties with gathering accurate vaccination data, yet they did not respond to whether or not the CDC was working to fix the overcounted data for Pennsylvania, the Inquirer reported. In September, a CDC spokesperson told the Inquirer that while the CDC was aware of the inaccuracies in their data, they had no timeline for fixing them. 

When examining the whole population, 72.8% of Pennsylvanians over the age of 18 are fully vaccinated, the Philadelphia Department of Health reported on Friday. As of October, 96% of all Penn students and 97% of faculty and staff are fully vaccinated.