COVID-19 Continues Rapid Spread Through US

Over the past week, a tremendous amount has changed in the world. Governments, employers, and social networks have advocated social distancing through travel bans, closures of schools, working from home, and countless other cancelled activities. The goal of these activities is to slow the spread of COVID-19 and protect vulnerable populations.

In our post that we released one week ago, data suggested the growth of COVID-19 was consistent, yet slower in the United States than in Europe. Continuing to use data from Johns Hopkins University Center for System Science and Engineering, we are now seeing that transmission rate change.

Updated Comparison of Growth

Since March 1st, 2020, the rate of transmission in the United States matches that of several of the major European countries. In Figure 1, we see the growth of COVID-19 cases grow at similar rates to Italy, France, Germany, and the United Kingdom.

Figure 1.

Confirmed cases of COVID-19 since March 1, 2020 for US and Four Major European Countries

China and South Korea had fast transmission growth months ago, but enacted strict social distancing policies. In Figure 2, we see the growth of COVID-19 cases in these countries has almost stopped, unlike in the US.  At these current rates, the number of confirmed cases in the United States will pass South Korea in less than a week.

Figure 2.

Confirmed cases of COVID-19 since March 1, 2020 for US, China and South Korea

An estimated growth factor for each country was calculated from the confirmed cases data. Of these seven countries displayed in Table 1, the transmission growth rate is the fastest in the United States, but not different from France, Germany, and the United Kingdom. Italy, South Korea, and China are statistically slower.

Table 1.

Table of the growth factor estimated and implied days to double for a number of countries, including the US

Forecasting Future US Cases

Using the data for confirmed cases in the United States since March 1, we created a forecast for the COVID-19 spread in the US over the next two weeks. The interactive forecast displayed in Figure 3 assumes the transmission growth rate of the last 14 days will continue over the next two weeks.

Figure 3.

From this forecast, we believe rapid growth of new cases will develop during the last week of the month. Our model also suggests that United States may approach half a million cases by the end of March. Whether this estimate is accurate or an overestimate is dependent on our ability to test patients and society’s willingness to comply with mitigation efforts.

References

Johns Hopkins University Center for Systems Science and Engineering. (2020). Novel coronavirus (COVID-19) cases [Data file]. Retrieved from https://github.com/CSSEGISandData/COVID-19

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