Tuesday 7 April 2020

Coronavirus: the truth. So far as we know

They say that the first casualty of war is truth. There’s no reason why the war against Coronavirus should be any different.

Generally, the problem is that governments are lying about what’s going on. You know, claiming to have shot down more planes than the enemy ever had, or claiming that a retreat is a strategic withdrawal to more defensible positions. Today, though, the mist over the truth is just the lousiness of the information.

For instance, we’ve been counting total numbers of infected cases. But we know that no country has the means to test every one of its citizens. So how can we know what the true figure is?

The number of infections in Germany is currently at about 70% of the number here in Spain. But the number of deaths stands at about 12%. Is that simply because they’re testing much more widely, and therefore identifying far more cases than don’t lead to death?

I’ve seen conflicting estimates of the true number of Spanish cases. Some authorities say they should be four times higher, others twenty times. Four times or twenty? How do you get anywhere near the truth with that kind of variation?

The same is true of the number of deaths. Some countries don’t count deaths in certain contexts. Maybe someone died outside a hospital and wasn’t tested. So they’re not included in the figures. On the other hand, if someone with CVid dies they may be counted as one of the deaths, even though they had underlying conditions, one of which may have been the real cause of death.

There are certain phenomena that are particular to certain nations. For instance, in the UK death figures can be reported over several days. The number of deaths reported for one day may therefore climb later.

In Spain, too, there’s a problem with weekends, when reporting may be delayed. That means figures may be low for Saturdays and Sundays, but exaggerated on Mondays. And that may or may not happen. 

That’s how exciting this all is.

Still, perhaps one can make a couple of assumptions, just as long as one remembers that they are assumptions and they are open to challenge as any assumption is.

The first is that however bad the figures may be, within a single country, they’re likely to be just as bad any day as they are on any other – or just as good. So if the case figures are a twentyfold underestimate on one day, then they’re likely to be a twentyfold underestimate on another. That means that comparing the figures over time may at least give a view of where we’re heading.

The second assumption is that the figures for a single day can jump about a bit. They may be up or down by chance. So it’s best to look at what happens over several days or a week.
Coronavirus cases (left) and deaths (right), by day, in Spain
Rolling seven-day average as dotted line
The black line marks the lockdown-start date
In the graphs, I’ve shown the daily figures for cases and deaths in Spain. I’ve also included a trend line based on how the average for the previous seven days has been changing. The trend line only starts on day seven, because no seven-day average can be counted before. The black line marks the day on which the Spanish lockdown began in earnest, 16 March.

Both lines show an uptick right at the end, but remember what I said about not putting too much weight on a single day’s figure. In any case, they’re for a Monday, so it’s possible they reflect late reporting at the weekend. Still, it’s possible there’s a real uptick. The lesson is that both figures can start growing again, whatever the prior trend may show.

That trend itself is at least a little encouraging. It does look as though both lines may at last be dipping. The deaths have not dropped as much as the cases, but that’s to be expected: patients dying today were probably first counted as cases a week ago.

It has, however, taken three weeks of strict lockdown to get here. Far stricter, for instance, than in the UK. As strict as Italy, where the figures also seem to be showing a tendency to drop.

This is, however, only the start of the drop. How long will it be until we get to figures so low that we can sensibly think about relaxing restrictions?

The Spanish government has started planning for that moment and one decision has already been taken: work regarded as non-essential, currently suspended, will start again on 11 April. But when will parks reopen? Or schools? Or bars and restaurants? That’s still unclear, but we do know that Wuhan, where the epidemic started, is only just beginning to relax, after eleven weeks of lockdown.

What this says to people in other countries is that lockdowns aren’t quick fixes. This is a long battle; restrictions have to be tough; they have to be in place for a longer period than any of us would like; and they can only be removed gradually.

Still, if we can trust the Spanish figures at all, they do seem to work.

Eventually.

No comments: