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Evidence shows that stay-at-home policies reduce COVID-19 infection rates

Despite the presence of hundreds of protesters demanding an end to stay-at-home policies designed to contain this coronavirus, polls show sizable majorities support their governors who are trying to flatten the curve and keep our health care system from being overwhelmed.  We need to test whether such stay-at-home policies worked as COVID-19 spread in early April.

A few weeks ago, I looked at evidence from history, showing that cities like Philadelphia who failed to heed the warnings were flattened by Spanish flu, while smart cities like St. Louis who practiced social distancing were able to flatten the curve against the scourge of Spanish Influenza.  Additional findings from 17 other cities backed this approach back in the 1918-1920 time frame, though such results were not applied to pandemics in the 1950s and 1960s, which explains those high death tolls.  Pragmatic policies were not adopted until the late 2000s.

But what do we know about evidence from COVID-19?  To determine this, I look at work from Thomas C. Frohlich from 24/7 Wall St.  You can follow along, if you’d like to as well (https://247wallst.com/special-report/2020/04/17/state-where-the-virus-is-growing-the-fastest-right-now/2/).  It includes data on virus growth rates, per capita infection rates, population density (for control purposes in my research) and how many days it took the state’s governor to issue a stay-at-home directive after their state had its first infection case.

Yes, several states have not issued stay-at-home directives at all.  So I took the number of days since their first case through April 25, 2020, the evening I conducted the analysis.

Here’s what I found.  For states that instituted a stay-at-home directive within three weeks or less, their COVID-19 infection growth rate in cases in early April (described by a program on NPR as the peak of the cases) was eight percentage points lower than state governors that took longer than three weeks to call for a state-at-home directive.

In fact, two of the top ten states with the highest rate of infection in April never put a stay at home policy in place.  One of those states that refused to pass a stay at home policy, South Dakota was the nation’s hottest hot spot, with a 139% increase in coronavirus cases in early April.  Of the ten states with the highest rate of infection growth in April, six of them took longer than three weeks to call for people to stay at home. 

Meanwhile, of the ten states with those lowest increases in infection rates, six of them put in place a stay at home policy in less than three weeks, a mix of 3 Democratic and 3 Republican governors.  Only one of the states in the bottom ten for low early April infection rates, Wyoming, never had a state at home plan, though their governor pleaded with Trump to declare a 50-state disaster area.

There’s an increasing level of partisanship in COVID-19 accusations.  But there’s not as much difference in party governors, though states with a Democratic Party Governor passed a state-at-home policy an average of six days earlier, had early April infection rates that were four percentage points lower, and ranked two states lower on the early April infection rate scale.

As states are pressured to reopen their economies while coronavirus infection rates still climb, we are millions of promised tests behind, and there’s no cure or vaccine in sight, we need to conduct studies like these, so we don’t continue to make the same mistakes down the road.