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Coronavirus Trends – what can we learn


We examine the coronavirus trends, and look at death rates from Covid-19, including absolute numbers, adjusted for population, and daily change rates. The daily change rates are declining for almost all countries, including Italy and Spain, but remaining alarmingly high for US and especially New York State.



Last week I examined Coronavirus Data and Poll Results, and we looked at the number of cases per country. These numbers continue to grow too fast for many countries, but even those large numbers may not be representative, because the testing is very uneven. Furthermore, there have been studies that suggest that 80-85% of all coronavirus cases are not reported.

The more representative and final measure is the number of deaths from Covid-19.

Here is an excellent chart from Financial Times journalist John Burn-Murdoch, who updates this and other charts daily.

Coronavirus Deaths
Fig. 1: Covid-19 Deaths in most affected countries, as of March 30, 2020.


While the above chart shows the absolute number of deaths, it does not show the relative impact on each country because it does not take the population into account.

Next chart shows the number of deaths from Covid-19 per million people. In addition to countries, we also added 2 regions: China-Hubei province and US-NY state.

Coronavirus Death Per Million, March 30
Fig. 2: Covid-19 Deaths per million people, as of March 30, 2020.


We note that Italy and Spain have been the most affected countries so far, with Spain numbers rising faster.

Netherlands and Switzerland lag behind Spain but also have very high growth rate. So does Belgium.

US overall has relatively low death rate, but the impact of coronavirus in the US is very uneven. We separate the New York State (US-NY), which is the hardest hit area, and it has the steepest rising curve.

UK and France seem to following Italy's curve. South Korea is the success on this chart with very low death rates.

Finally, to understand the trends, we look at the daily change rate in the number of deaths, defined as
DChange(N)=(Deaths(N+1) / Deaths(N)) -1
where Deaths(N) is the number of deaths on day N.

Note that the death change rate would be the same for absolute number of deaths as for the deaths adjusted by population.

The actual rates fluctuate a lot, especially in the first week or two, so we smooth them by taking a 5-day moving average. Ideally, we would use a 7-day moving average, but some countries do not have enough data. This chart is shown in Fig. 3.

Coronavirus Death Change Rate, March 30
Fig. 3: Covid-19 Daily Death Change Rate, as of March 30, 2020.


We see some hope in that almost all the lines are declining, indicating some progress in limiting the spread of coronavirus.

We note that although the total numbers in Italy grow, the rate of growth is declining and is now down to about 10%.

Iran has an even lower rate of growth, but their line looks suspiciously straight in the last 2 weeks, compared to almost any other line , which raises questions about the accuracy of their reporting.

Spain rate is now about 20% and is declining and tracking Italy with a delay of 10-12 days. France rate has declined dramatically after spiking in the first 2 weeks and is now 19% and has downward trend.

Among the more developed countries, US has the highest rate of growth of death cases, around 28%. Much of this is driven by the New York State (US-NY), which has about half of all US deaths, but only about 6% of US population.

For more up-to-date information, see our Topic: Coronavirus page, with links to data and several excellent dashboards.

I am not an epidemiologist, and I am NOT making any predictions here, just visualizing the current data.

Here are the very worrying COVID-19 Projections from the experts in U. of Washington, which have been used to set the current US policy.

Their model assumes continued social distancing in USA until May 31, 2020, and the chart below, with almost 100,000 deaths in USA is their optimistic scenario.

Covid19 Death Projections Mar31
Fig. 4: Covid-19 Death per day projections by U. of Washington, as of March 31, 2020.


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