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  • Writer's pictureLeon Grice

COVID-19 to increase right through US election

Today, 24 October (NZT) eleven days out from the US election on 3 November we can report that COVID-19 is continue to spread - see here. Our model's Reff calculation allow us to project the next 10 days and it is likely that the spread will continue until at least the election.

On 23 September here we noted that our model was showing that the US reproduction rate had clicked above 1.0 and while daily cases numbers were comparatively low it was an early warning. We tracked the growing problem and reported on 5 October here and on 12 October here.

The US now has Reff=1.25 and it has been above 1.0 since 18 September 2020 giving time for the disease to build. The numbers of daily cases is now starting to exceed the first wave in July. The pattern of spread is reasonably consistent across the US with concentrations building in the northeast, the south, the midwest, and the mountain western states.

Let's look at today's data for some of the swing States in the US election, namely Florida, Pennsylvania, Michigan, Wisconsin, North Carolina, Arizona, Georgia, Ohio and Iowa. We chose these swing states from and All of these swing states have a reproduction rate above 1.0. Only, Florida, Georgia and Iowa have Reff less than the national average. Wisconsin has the highest with Reff=1.8, followed by Michigan (1.5), Ohio (1.5), Arizona (1.4), North Carolina (1.4) and Pennsylvania (1.3). Below we provide a short precis on each State except Georgia and Iowa. But you can look at Georgia here and Iowa here to assess the trends their for yourself.

Wisconsin is being hit by its first real wave

Wisconsin has had a Reff>1.0 since the beginning of September. The county for Milwaukee has a Reff rate greater than 2.2 and COVID-19 is growing mostly in the southeastern corner of the State. Daily cases will continue to grow in the next ten days at least.

Michigan's second wave is hitting harder than its first

At Reff=1.5, Michigan is experiencing a second wave with daily case numbers already higher than in April 2020. COVID-19 seems to spreading mostly across the counties in the south of the State. The reproduction rate has been above 1.0 for well over a month, so it reasonable to expect that daily new cases will continue to grow over the next 10 days.

Ohio's second wave is bigger than its first also

Like Michigan, Ohio has Reff=1.5 and the disease seems consistently spread across the State and its major cities. Daily new cases are growing rapidly. Cases can be expected to continue to grow for the next ten to fourteen days (Note: we do not like to forecast beyond 14 days as after the time period human behavior changes start to have an impact and human behavior is hard to model.)

Arizona's Reff=1.4 but its new daily case numbers are a lot lower than it was in July. It might be able to turn around the spread of the disease with the right epidemiological interventions. You can see that the rate of increase is relatively evenly spread across the State in most counties.

The number of North Carolina's new cases being reported to the Johns Hopkins database has been whipsawing through October and our model's current assessment of Reff=1.4 is consequently bounded by wider confidence intervals. North Carolina's second wave appears on track to be worse than in July and August and daily case growth are likely to grow for the next ten days.

Pennsylvania's reproduction rate went above 1.0 in early September and the trend has had seven weeks to build. Its second wave looks to be almost on par with its April-May surge in cases. While its Reff has been only marginally above 1.0 since September and is currently Reff=1.3 its the length of time it has been above 1.0 that gives the pandemic's exponential dynamic time to build. The confidence intervals around the Reff=1.3 are comparatively narrower than North Carolina reflecting the greater consistency of the new daily case numbers reported to Johns Hopkins.

Florida's July-August wave regularly reported new daily cases above 10,000 people. After that surge it consistently fell in August and settled on around 3000+ cases per day. Our model indicates that Florida's Reff=1.2, but bounded by relatively wide confidence intervals.

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