New Coronavirus Dashboard Frequently Asked Questions

Why are the estimates on Baltimore City’s COVID dashboard for “Latest 7-Day Average, Daily New Cases per 100K People” different from the CDC’s estimates for “New COVID-19 cases per 100,000 population in the past 7-days”?

The estimates are different because they are calculated in different ways. BCHD, like the Maryland Department of Health, calculates the COVID new case rate as the number of new cases in a day, divided by the population size each day. Then, BCHD uses those estimates to calculate the 7-day average. The CDC calculates the COVID new case rate as the number of cases over 7 days, divided by the population size.

The CDC notes that “COVID Data Tracker may display data that differ from state and local websites. This can be due to differences in how data were collected, how metrics were calculated, or the timing of web updates.” Source:, accessed 3/24/2022.

Why haven’t the metrics for CDC COVID Community Level changed for a few days on Baltimore City’s COVID dashboard?

The CDC updates the COVID Community Level data once a week (on Thursdays). So, you can expect them to be updated on the city dashboard by Fridays.

Why are there odd spikes in the case and death graphs and negative numbers? Do those represent real trends in cases and deaths?

These negative numbers and spikes (on 2/20/2022 for cases and 5/27/2021 for deaths) are due to corrections in data by the Maryland Department of Health. They do not represent real trends in cases and deaths. They represent corrections to the data by report date.

Why was Baltimore City’s COVID dashboard not updated from December 4, 2021, to March 23, 2022?

Due to a cybersecurity incident involving the Maryland Department of Health (MDH) in December 2021, there was a pause in BCHD receiving COVID case, death, testing, and vaccination data from MDH. COVID hospitalization data were not affected and continued to be updated Monday-Friday. For additional details, please visit

Why was Baltimore City’s COVID dashboard updated on March 24, 2022?

On March 24, 2022, BCHD switched to “open data” made publicly available by MDH and CDC. This allowed BCHD to update Baltimore City’s COVID dashboard for new cases, deaths, positivity, test volume, and vaccination even though MDH has not restarted data streams affected by the cybersecurity incident in December 2021.


Content last updated: 4/1/2022