Charting COVID-19 by country: Early actions brought big rewards

Updated 1 July 2020 with the latest case and death numbers as of 28 June, and updated analysis on actions and reactions from around the world as COVID-19 continues to evolve.

The rapidly changing dynamics of this invisible enemy and its march around the world cut across many political and social dimensions.  All raise the important question of timing.  What's the best, most effective time for interventions to begin, and now, to be lifted?  What's realistic? What's safe? What's practical?

There are no clear answers, but we can draw insights by comparing the magnitude of the spread and growth in cases and deaths across each country and testing their relative success against the invisible viral enemy.

Using a common "time zero" for comparison purposes

Drawing accurate comparisons across countries is difficult as each one began programs of social distancing, lock downs and aggressive testing at different times and with varying degrees of intensity.  This makes it harder to understand the magnitude of the spread by country and a country's relative success in the fight against the virus

To give more meaningful comparison and insights, it's helpful to plot the progress from a common "time zero" event.  For purpose of our analysis, we established a common time zero event as the date when cumulative deaths exceeded 10 or cumulative cases exceeded 100. This presents a more revealing picture of the scope of the disease.

The plots used are based on the number of cases and deaths as of 28 June 2020.

Many Western nations underestimated the benefits of strong early interventions

In our analyses, we focus on eight countries: US, UK, China, France, Spain, Italy, Japan and South Korea. We consider Hubei Province separate from all of China because using the overall picture for China leads to some distortions as the pandemic was very well controlled outside of Hubei Province.

We selected the most informative graphs in the series below which tell an interesting story:

  1. Countries that adopted early and comprehensive measures clearly controlled both the magnitude of the disease and shortened the overall time from the peak to having a manageable, small number of cases. These measures included social distancing and lockdowns, sometimes in conjunction with contact tracing and isolation.
  2. Among the countries selected, Japan and South Korea are notable exceptions in that they managed to control the spread from its very beginning due to Japan implementing strict control measures and South Korea's extensive testing program in conjunction with controls early on. Japan has seen increased growth rates of deaths beginning of April, see figure 2, but these growth rates are still much lower than in Western countries.

Figures 1 and 2: Absolute progression is faster outside China (except for Japan and South Korea)

First, we look at the progression of the absolute number of cumulative deaths across countries. Figure 1 shows the progression has been much faster in all countries compared to China (blue line)/ Hubei (red dash) with notable exceptions of Japan (green line) and South Korea (purple line). This also illustrates how much higher the death count is in Western nations compared to China, plus that the number of deaths continued to climb dramatically, well after the period from time zero when China began to see the number of deaths level off.

The black dots represent the date when lockdowns or stringent social distancing measures or "interventions" were imposed. The US (red line) individually initiated interventions quite late compared to other countries, and many states started reopening earlier than other countries at a similar stage of the pandemic. This is likely to cause a continued steep increase in the number of deaths over the coming weeks. Responding to a significant resurgence in recent weeks, states such as Florida, Texas, and Arizona are now imposing stricter measures than at the beginning of the outbreak. Other states that partially reopened are reconsidering or reversing decisions on lockdown status.

The conclusion is this: the early and strict measures in China plus extensive testing clearly helped control the pandemic. South Korea and Japan are excellent examples where social distancing measures and - for South Korea in particular - stringent testing, contact tracing and isolation helped to keep the virus at bay. Although there have been sporadic reports of spikes in Beijing and Seoul, so far these countries have avoided a second wave.

Figure 1: Comparative of number of cumulative deaths, time zero = 10 cumulative deaths

These conclusions are even more apparent when we plot the log of the number of deaths. Log plots are useful to depict the rate of growth. The steeper the curve, the faster the growth. In figure 2, we can see that Spain (blue dash) appears to have had the fastest initial growth rate with UK (green dash) a close second and Italy (orange line) and France (orange dash) vying for third. The US experienced a slow growth rate initially (probably due to limited testing) but has picked up pace and is currently experiencing the fastest growth rates among this set of countries. As the initial spread in European and Asian countries is believed to be over, the focus has now shifted further west, as the US has breached 125,000 total deaths. The situation in Latin America continues to be of concern with many countries whose number of cases or deaths have yet to peak.

Figure 2: Comparative of log plot of number of cumulative deaths, time zero = 10 cumulative deaths

Figure 3: Death rates in European countries are lagging the experience of Hubei Province

It's also helpful to understand the growth in "death rate" from the virus, which expresses the deaths per 100 million of population. For this, we look at the log plot of cumulative cases per 100 million. This plot shows the Hubei Province death rate has been much higher than overall China mortality, proving that interventions and the lockdown, along with contact tracing, effectively contained the pandemic within the Hubei Province, while in Hubei itself early opportunities to contain the spread were missed.

Figure 3 shows the death rate in UK (green dash) is currently the highest of the selected countries/regions, closely followed by Spain (blue dash) and Italy (orange line). The UK (green dash) is on track to perform the worst globally in terms of the peak death rate, despite now showing a significant decrease. Across all western countries, Belgium (not charted) has the worst death rate but officials have explained this is likely due to expansive guidelines for what's recorded as a COVID-19 death compared to other countries, and a smaller and more dense population.

Hubei's death rate (red dash) began to level off at about 25 days from time zero, but Western nations still exhibit an increasing rate. With 61 million people, Hubei Province is a good comparative to other European countries. 

Figure 3: Comparative of number of cumulative deaths per 100 million, time zero = 10 cumulative deaths

Figure 4: Observed cases per 100 million of population shows Western nations clearly faring worse

Looking at case rates (in addition to deaths) per 100 million can also be insightful. We see the growth in case rates in Western nations has exceeded that of East Asian countries at the same phase for a while now, and at present all observed Western nations in this study have exceeded Eastern nations – and Hubei – in case count per million. The initial spread in Hubei was quickly arrested, with Western countries, and the rest of China, having a larger overall case count.  

Note that there might be substantial differences between reporting of cases due to limited testing capacity and variance in testing strategies (for example broad population-wide testing in Iceland or testing of at-risk population in the Netherlands). The time series for deaths, shown next, are therefore considered much more reliable to draw conclusions on the effectiveness of the control measures.

Figure 4: Comparative of cumulative cases per 100 million, time zero = 100 cumulative cases

Figures 5 & 6: Case and death rates slowing as social distance breaks the spread

A plot of the 5-day moving average of the increase in cases does show some positive news. Though the new number of cases and deaths continue to be quite high, the rate of growth has come down in most countries. The US (red line) is still leading with new case growth rates. Not only is a resurgence occurring in some areas of the US, other states are being affected for the first time. South Korea (purple line) is also very high, but this is less of a concern. Having weathered the initial outbreak extremely well, South Korea has seen a sharp spike recently. They were able to control the initially outbreak so well due to both a rigorous track and trace regime, helping to identify all of those who are infected, and the impact of super-spreaders. These individuals infect a disproportionately large number of people, while often remaining asymptomatic or only mildly infected.

Either way, the success of the countries least affected is directly linked to their use of intervention methods such as social distancing, school closings, lockdowns and other measures implemented in areas where the virus hit the hardest.

Most countries went into lockdown soon after case counts exceeded 100 and deaths exceeded 10. The relative daily increase of deaths is insightful as it shows that countries need to keep up their efforts to get to where Hubei Province in China stood at 60 days post lockdown.

Figure 5: Moving average of relative daily increase in cumulative cases, time zero = 100 cases
Figure 6: Moving average of relative daily increase in cumulative deaths, time zero = 10 deaths

The virus must be tackled early with strength and continuous determination to blunt its destruction

The message from these charts is clear: social distancing, lockdowns, travel restrictions and other actions in conjunction with widespread testing early in the pandemic blunt its speed and magnitude effectively.

When localised spikes emerge, authorities must be swift to re-enact stronger measures to blunt any chance of a second wave.

The lessons learned in the first wave are proving to be invaluable as countries start to remerge from lockdown.

Countries which have yet to see the virus run its course, such as Brazil and India, would do well to follow the lead of Asian countries. As a continent, Africa has yet to be severely affected and has had the most chance to prepare for the possible spread. Europe is mostly reopening, with governments ever vigilant for a second wave toward the end of the year.

As the economic damage mounted, political pressure to remove restraints, despite health consequences, rose quickly across Europe, and is still being felt in the US. As countries get closer to the point at which China started easing its restrictions, they must think about how to manage recurring outbreaks. A key measure to consider is when to lift travel restrictions for everyone. We have seen that in many Asian countries, an easing of travel restrictions triggered a minor recurrence.  As Western nations are only now permitting international travel, can they take a similar path to East Asian nations to continuously manage through contact tracing, limiting travel and other control measures?

With each week, we continue to learn more about this disease with such a complicated impact on mortality across the globe. We'll look at this indepth in our next L&H Trend Spotlight.

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