Ohio has 17% more residents than Michigan.

Its first confirmed case of coronavirus COVID-19 was Feb. 15, more than three weeks before coronavirus came to Michigan.

Yet as of April 13, Michigan had 24,638 confirmed cases of coronavirus compared to 6,518 in Ohio.

Why?

Michigan is doing the right things on coronavirus. So why is the caseload so high?

Here’s some the factors that separate the coronavirus outbreaks in Michigan and Ohio.

1. Metro Detroit has an international airport and a business community with an unusual amount of international travel.

While travel has largely shut down in recent weeks, public-health experts theorized that international travelers helped to “seed” coronavirus into Michigan during late February and early March.

They note Detroit Metro Airport has been one of only 13 in the country and one of only two in the Midwest along with Chicago’s O’Hare International Airport with flights from Europe and Asia since the COVID-related travel restrictions.

And between the airport and the auto industry, Detroit metro area “is an incredibly interconnected region” in terms of global commerce, said Emily Martin, an epidemiologist for University of Michigan.

“We’ve got a major airport. We have a lot of international businesses here,” she said. “We have a lot of travel in and out."

And it’s particularly striking when you look at Michigan’s business ties to China, South Korea and Italy, others say.

“How could that not have an impact, when you have people traveling through Detroit from countries with COVID outbreaks?” said Dr. Dennis Cunningham, an infectious disease specialist in Flint.

2. Michigan has a more concentrated urban population than Ohio.

About 43% of Michigan residents live in metro Detroit. By contrast, the metros areas of Cleveland, Columbus and Cincinnati each have about 17% of Ohio’s population.

Conoravirus thrives in more densely populated communities. So the fact Michigan’s population is concentrated in one area instead of three makes a big difference. Moreover, Michigan’s urban core is more densely populated than any of the three in Ohio.

About 80% of Michigan’s coronavirus cases are in metro Detroit. The Ohio cases are much more spread out: 17% in metro Cleveland, 14% in metro Columbus and 8% in metro Cincinnati.

3. Michigan’s March 10 primary election.

It’s likely -- even probable -- that Michigan’s March 10 presidential primary helped fuel the spread of coronavirus in metro Detroit.

For days leading up to the primary, Bernie Sanders and Joe Biden were holding campaign rallies and get-out-the vote events in southeast Michigan, where the state’s Democratic voters are concentrated. The election itself drew 2.3 million voters.

Two and a half hours after the polls closed on March 10, Gov. Gretchen Whitmer announced the state had confirmed its first two cases of coronavirus.

By contrast, Ohio’s primary was scheduled for March 17. Both Sanders and Biden canceled campaign events after the Michigan election, which meant there were no rallies or mass gatherings in Ohio that week, and Ohio Gov. Mike DeWine canceled the election itself on March 16.

4. Michigan has more concentrated poverty.

Nowhere in Michigan has coronavirus been more problematic than the city of Detroit, which has almost as many cases of coronavirus as all of Ohio.

One reason that Detroit is a hotbed of coronavirus: It’s the nation’s largest, poorest city -- and that combination of large population and high poverty makes the city especially vulnerable.

People in low-income households are more likely to have health issues such as diabetes and asthma that make coronavirus a more serious illness. They are less likely to seek medical help until they are seriously ill. Low-income residents are less likely to be able to follow social distancing guidelines because they rely on public transportation, more likely to live in communal housing and less likely to have jobs that can be done at home.

Cleveland also has a very high poverty rate and sociodemographics similar to Detroit. But Detroit has twice the population. And that, along with the other factors that have fueled the numbers in Michigan -- including Detroit’s proximity to Detroit Metro Airport and the March 10 election-- helps explain why Detroit had 6,501 coronavirus cases as of April 13 compared to 312 in Cleveland.

5. Ohio was especially aggressive in shutting down.

Whitmer has been given high marks by many for being aggressive in shutting down schools, bars and restaurants and issuing a stay-at-home order.

But DeWine has consistently moved ahead of Whitmer, and is cited as perhaps the most pro-active governor in the country.

On March 3, before the state had any confirmed cases of community spread of coronavirus, DeWine canceled the Arnold Classic, a body-building and fitness expo in Columbus. He banned gatherings of 100 people or more on Thursday, March 12, a day before Whitmer issued a similar ban.

DeWine was the first governor to close in-service dining for bars and restaurants, issuing that order on Sunday, March 15, a day before Whitmer followed suit. The Ohio stay-at-home order was issued on March 22, the day before Michigan’s stay-at-home order.

6. Michigan has tested more people.

This is probably the least-important factor, but worth mentioning. As of Monday, April 13, Michigan had tested about 76,000 people for coronavirus, about 20% more than the 63,000 tested in Ohio. That more testing, the most cases likely to be identified.

CORONAVIRUS PREVENTION TIPS

In addition to washing hands regularly and not touching your face, officials recommend practicing social distancing, assuming anyone may be carrying the virus.

Health officials say you should be staying at least 6 feet away from others and working from home, if possible. Carry hand sanitizer with you, and use disinfecting wipes or disinfecting spray cleaners on frequently-touched surfaces in your home (door handles, faucets, countertops) and when you go into places like stores.

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