Photo: Getty
Photo: Getty

SocietyJune 3, 2020

The week in Covid-19 data: False finishes across the globe

Photo: Getty
Photo: Getty

Here’s The Spinoff’s weekly round-up of data tracking the effects and response of Covid-19 around the world – and how New Zealand stacks up.

Our weekly summaries of data and visualisations use Our World in Data’s work on the Covid-19 pandemic, which is freely available for re-use. Not all data is complete: measurement techniques vary between countries and sometimes within them. Details for each country can be found here.

The countries we’ve chosen to compare are New Zealand, Australia, the US, the UK, South Korea, Sweden and Singapore. Where possible, we’ve included China and Taiwan; there is less data available from these countries so it can’t always be included.

Deaths per million

Shown is the rolling seven-day average of daily deaths per million people. Limited testing and challenges in attributing the cause of death to Covid-19 mean that the number of confirmed deaths may not be an accurate count.

April was Sweden’s deadliest month in 27 years. Its daily deaths per million rose from 4.51 up to 5.7 last week, showing that the trouble is far from over. However, that country’s chief epidemiologist Anders Tegnell believes that in a year’s time, the overall number of deaths will match up with its neighbouring countries.

Every other country we are tracking has decreased or stayed at zero, except New Zealand. One death was added to our tally last week, meaning our average daily death per million rose to 0.03.

Case fatality rate

The case fatality rate (CFR) is the ratio between confirmed deaths and confirmed cases. CFR isn’t always the best measure of a disease’s risk, because it measures confirmed cases and confirmed deaths. In some instances, cases are missed due to low testing rates; in others, deaths attributable to Covid-19 aren’t recorded as such.

One explanation for a low CFR is the capacity of a healthcare system. In Australia, New Zealand and much of Asia the case numbers were low enough for hospitals to cope. In the UK and Sweden the virus spread quickly, so medical centres were overwhelmed.

The UK, once again, has seen a small decrease in its CFR, coming down from 14.18% to 14.01%. This means Covid-19 is very slightly less lethal in the UK now, but it’s still the highest CFR on our chart. Sweden, too, has taken a small dip and has fully breached the 12% line to hit a strong 11.7% CFR. On Sunday, the lockdown-free nation celebrated its first day without a death in 11 weeks.

Age of population

Ageing populations are assumed to be hardest-hit by Covid-19, and it’s true that age increases the risk that the virus will be more severe, or even lethal. This map displays the percentage of a population over the age of 70. We can see that the UK, Italy, Sweden – places where the CFR is high – also have some of the oldest populations in the world.

However, Finland has an older population than the UK and one very close in proportions to Sweden; Japan’s population is older than both; and so is Germany’s. All three have lower CFRs. While Covid-19 is far more dangerous for those over 70, it is not necessarily a death sentence.

Case increase rate

The total number of cases is likely higher than the confirmed number of cases, because testing rates aren’t high enough in some countries to capture everything.

On March 23, New Zealand case numbers passed 100. That brings us to 71 days on the y axis here; we’ve been very steady around the 1,000 case mark since roughly day 20. Taiwan has roughly the same trajectory, but with far fewer case numbers. Australia was slower to even out and therefore has a higher total case number, but has flattened out. South Korea’s still wobbling; as we discussed last week, it had a small surge after it eased lockdown restrictions.

The trajectories of Sweden (the unlabelled dark blue line above Singapore) and Singapore are still on an incline; the virus has spread quickly in the migrant worker dormitories of Singapore.

It’s hard to say when Sweden’s increase in cases will tail off, as the presence of Covid-19 antibodies in its population is lower than expected at 7.3%. It’s also unknown what level of antibodies is required for immunity, so there’s a chance this 7.3% isn’t actually immune to Covid-19. When the “first wave” stops and “second wave” begins could be difficult to say for countries like this.

Daily confirmed cases

As we edge close to eliminating Covid-19 in New Zealand, it’s worth looking at other countries that have done so already. As we can see in the graph above, it’s uncommon to get to zero and stay there.

In Cambodia, a nation of 17 million,one infected patient flying in across the border broke a month-long Covid-free streak.

The same thing happened in Trinidad and Tobago on May 30, after they declared themselves Covid-free only a week earlier.

Hong Kong (no data available) just reported five new cases after two weeks with zero new cases, and an overseas link is not yet clear.

Keep going!