Michigan COVID-19 Timeline

Here we present a timeline of major COVID-19 milestones, executive orders and actions taken in Michigan to reduce crowding and enforce social distancing, and how the trajectory of cases has changed since COVID-19 began to appear in Michigan.

Early, aggressive action taken starting March 12th (by closing K-12 schools), through March 23rd (issuing the Michigan Stay Home, Stay Safe order) does appear to have curbed the trajectory of COVID-19 infections in the state, or ‘flattened the curve’, with infections levelling off around April 6th.

However, even with 2 months of a stay-at-home order, there are still hundreds of cases per day, indicating that there are still substantial infections in the state of Michigan. When social distancing precautions begin to lift with the end of Governor Whitmer's Stay Home, Stay Safe period, vigilance will be necessary.

What is the relationship between changing behavior and COVID-19 case rates?

Since the discovery of the SARS-CoV-2 virus in China late in 2019, the disease caused by infection with this virus, COVID-19, has rapidly spread around the globe. In the United States, the first case was detected on January 22, 2020. Data from John Hopkins University shows that in the months since the first case was detected in the United States, there are now nearly reported cases and deaths across the country due to COVID-19.

There are currently no approved treatments for COVID-19, and there is no vaccine. The CDC has guidelines on what to do if you are sick, but because there are no effective treatments or ways to prevent infection, the best tool we have to protect ourselves and our communities is social distancing. Social distancing means keeping about 6 feet of distance from others, staying home whenever possible, and avoiding groups.

However, even with aggressive social distancing policies put in place by Governor Gretchen Whitmer, cases are not disappearing altogether, and only very recently are we seeing evidence of a steady decline. Part of this is due to the fact that there is a long delay between getting infected with COVID-19 and being sick enough to get tested for COVID-19. After exposure to COVID-19, it typically takes 4-6 days to develop symptoms, though it can take as long as 14 days.This means that there is up to a two week delay between when someone comes into contact with the virus (either through a sick person or touching a contaminated surface) and when they begin to show symptoms.

80% of those infected with COVID-19 appear to have mild to moderate illness, and may not seek testing at all. For those ~20% whose symptoms progress to more severe illness, it takes about 5-8 days to experience shortness of breath, 8-12 days to acute respiratory distress syndrome, and 10-12 days to be admitted to the ICU. Thus in settings where tests are administered most commonly to those who are experiencing severe symptoms and/or seeking hospital care, there could be as much as a month delay between exposure to COVID-19 and seeking treatment where a patient would receive a COVID-19 diagnosis. This means that we can expect up to a 4 week delay between changes in social distancing behavior and changes in case and mortality rates.

As the state begins to reopen, recall that this delay applies not only to decreasing cases after social distancing measures are enacted, but also to increasing cases after those distancing measures are relaxed.