Maryland’s Department of Health said in a Thursday announcement that it revised the state’s COVID-19 death count to include deaths that were not properly classified by medical certifiers over the past year. The department’s statistics administration added 517 confirmed COVID-19 deaths and 21 probable cases to its total death count, bringing the overall tally to over 9,500.

“When necessary, our epidemiologists make adjustments to reported health data as information is reviewed, verified, and corrected,” said Maryland’s deputy secretary for public health services, Jinlene Chan. “It is important for medical certifiers to closely follow [Centers for Disease Control] guidance when reporting COVID-19 deaths. This data is critical for the public and the public health community, and our systems and processes are designed to ensure accuracy and transparency in our reporting to the public.”

The department’s COVID-19 death data are updated as changes to death records are received, it said in a press release. Maryland’s Vital Statistics Administration was performing maintenance exercises when it recognized that some medical certifiers had miscoded the cause of death for these cases.

The data error spiked the daily death count to well above 500; over the past month, Maryland’s daily case count has ranged anywhere from 3 to just above 20. A health department spokesperson told The Washington Post, however, that these uncounted deaths occurred throughout the pandemic, many during the spikes in spring and winter of 2020.

Similar technical issues have shifted numbers in D.C.’s and Virginia’s tallies over the course of the pandemic.

Even with the case anomaly, Maryland’s case positivity rate fell to 1.84% on Thursday, and the region’s seven-day average fell below 700 for the first time since April.