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Coronavirus: an estimate of the real number of infections in Switzerland


Today, according to the Federal Office of Public Health (FOPH), there were 815 confirmed cases in Switzerland.

There are obvious challenges to this figure. Possibly the most important is the time lag between infection and a confirmed case.

On average, there are 5.1 days between catching the virus and the onset of symptoms.

If you look at the chart above from a WHO report on COVID-19 in China, which shows new coronavirus cases from 8 December until 20 February for all of China, you’ll see there are orange and blue bars. The orange bars represent confirmed cases. The blue ones are actual cases – these are calculated by counting backwards from when the symptoms appeared, something that can only be done in retrospect.

Нew coronavirus cases from 8 December until 20 February for all of China

Нew coronavirus cases from 8 December until 20 February for all of China

- Click to enlarge

On 24 January 2020, there were around 1,000 confirmed cases. This is the sum of all the orange bars up to and including that date. Now add up all of the blue bars up to and including 24 January 2020 and you’ll arrive at a cumulative total of more than 16,000 actual cases.

In the early phase of the epidemic in China when there were 1,000 confirmed cases, there were 16,000 actual cases, 16 times the number of confirmed cases. They just couldn’t see all these cases because most patients hadn’t shown symptoms and tested positive.

A few days ago, medical professionals in Switzerland were instructed by the FOPH to reserve testing for high risk patients with symptoms, which includes those over 65 and those with certain underlying illnesses. So, many of those with symptoms are no longer tested.

In addition, many with the virus are asymptomatic or have symptoms so mild that they’re not aware they have the illness. In a number of Asian countries they tested people without symptoms that had been in contact with people testing positive. But Switzerland isn’t systematically testing this group.

Given the patchy testing in Switzerland, the 815 confirmed cases could be much higher. If we conservatively assume that with better testing they’d have identified 1,000 cases in Switzerland, then as we saw in China, there could be well over 16,000 actual cases.

From here, the number cases in Switzerland is set to rise fast. One difference between China and Switzerland is that China appears to have contained the spread. However, there are no signs that Switzerland has managed to do the same thing. In Switzerland, there has been little of the lockdown, testing, cleaning and vigilance that contained the spread in China.

Epidemic Curve of Confirmed Covid-19

Epidemic Curve of Confirmed Covid-19

- Click to enlarge

If you look at the epidemic curve above from a recent WHO COVID-19 situation report it offers some insight into the near future. The bars in this chart are new confirmed cases outside China between 30 December and 8 March. The pink bars, which represent new cases in Europe, show total confirmed cases roughly doubling every two days from 1 March 2020. If Switzerland is on a similar curve it could reach 100,000 actual cases next week.

In the UK, they have belatedly presented more realistic figures. This evening, the UK’s chief medical officer admitted that up to 10,000 in the UK are “likely to have coronavirus”, a large number when compared to the 459 confirmed cases. He also said “we’re in a period where we’ve got some cases but it hasn’t yet taken off.”

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About Le News
Le News
The newspaper Le News is a free, quality, local English language newspaper launched on 31 October 2013. Le News fills a gap in local Swiss media for the numerous English-speakers living and visiting Switzerland. In late January 2015 we decided to put our print medium on hold and focus on our digital media presence.
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