Policy Corner: Data tells the story of COVID-19

Numbers tell the story of the COVID-19 pandemic. Even with all the data points that are routinely calculated after more than 10 months of the outbreak in Illinois, readers often want more.

We aim to provide it, along with some perspective.

It's not meant to scare anyone, though the numbers often have been scary.

Illinois public health officials report a panoply of statistics on COVID-19. Cases and deaths are the at-a-glance backbone of the daily update, and are still relevant.

Tracking the data allows us to point out, for instance, that January was Illinois' third deadliest month for COVID-19, even amid optimism about vaccines. It will enable us to report on the effect, if any, of a rollback of restrictions last week across the suburbs.

The array of numbers has evolved in this fast-developing crisis, and our reporters have become experts.

Take "probable cases," a term that swept in people who died of apparent COVID-19 without having been tested, and later, people who tested positive via rapid-result antigen tests rather than the gold standard molecular tests. In November, 8,000 cases were moved from the "probable" column to the total cases column in Illinois, under the guidelines of the U.S. Centers for Disease Control and Prevention.

Our reporters sorted it out for readers in a story Nov. 12.

We report deaths, now 19,138 in Illinois, and we report recovery rates, now 98% of the state's 1,120,528 cases.

We report the positivity rate, which indicates how fast the disease is spreading and, indirectly, a person's relative risk of being exposed in the community.

Now, the vaccination data is the most closely watched, and the focus of our reporting.

It also has its subtleties: Number of doses delivered, number of shots in arms, number of people fully vaccinated with the recommended two doses.

All the metrics are different, but together they tell a story that will be analyzed for decades after our COVID-19 era has passed.