Coronavirus: the maths behind the panic

Viral: Iran’s deputy health minister mops his brow. Hours later, it turns out he has Covid-19. © Getty

How worried should we be? The headlines shout: “killer virus”, “crisis”, and “confusion”. Italy accuses misleading media of creating an “infodemic”. But what do the numbers say?

Global stock markets are plummeting amid warnings of school closures, self-imposed quarantines, and mass testing. The first case is reported in sub-Saharan Africa. Top sports events are under threat.

But what do the cold, hard numbers say?

The spread. The World Health Organisation (WHO) has now recorded over 81,000 cases and 2,800 deaths from Covid-19. Of the 50 countries affected, China is by far the worst, with 78,191 cases at the last count. South Korea comes next, with 1,261 cases. In Europe, there have been 470 confirmed cases – 400 of them in Italy – and 14 deaths. Britain has 19 cases so far.

The risk of infection. The number of people infected so far is equivalent to a little over one in 100,000 of the global population. At present, that means you have the same chance of being infected as being murdered in the UK, or choking to death on a fishbone if you lived in the US. However, as the virus continues to spread, one leading academic, Professor Marc Lipsitch of Harvard University, believes that 40-70% of people around the world could contract it within the next year.

The risk of death. The figures to date indicate that about 1% of people who contract the coronavirus die from it – mainly, elderly people with pre-existing health problems. However, a study by Imperial College London points out that this does not account for people who have the virus, but show no symptoms. If there are a lot of them, as many scientists suspect, then the proportion of those with a fatal infection could be under 1%.

How it compares. The Spanish flu pandemic of 1918 to 1920 is thought to have infected 500 million people – around a quarter of the world’s population. Estimates of how many died vary from 20 million to 50 million. The Sars epidemic of 2002 to 2004 resulted in 8,098 infections, and took 774 lives. There were 28,600 reported cases of the Ebola virus in West Africa between 2014 and 2106, of which 11,325 were fatal.

Other diseases. In the US alone, an estimated 19 million people have caught flu this winter – 180,000 of them badly enough to go to hospital; 10,000 have died. Cancer kills around 165,000 people a year in the UK; 50% of those diagnosed with it survive for 10 years or more.

Other killers. According to the latest global figures (from 2016), we are most likely to die from heart disease, which killed more than 12 million of the 57 million people who died that year. Strokes accounted for approximately six million deaths; respiratory diseases, such as pneumonia, for three million; Alzheimer’s for two million, and lung cancer for 1.7 million. Around 1.4 million people died in road accidents.

The worst case. According to the Sun, a UK government report called “Covid-19 Reasonable Worst Case Scenario” suggests that cases in this country could snowball over a period of two to three months, with 80% of the population becoming infected. More than two million people could be hospitalised, and half a million might die.

How worried should we be?

No sweat?

Some say that this could be one of the biggest pandemics the world has ever seen. Although the percentage of fatalities is small, the ease with which the disease seems to spread means that, ultimately, the number of deaths could be enormous. It is particularly difficult to deal with because people today travel so widely, and it can be spread by carriers who are unaware that they have it.

Others argue that the danger from the virus has been exaggerated: the main reason it spread so widely in China is that the authorities were slow to acknowledge its existence. Other countries will be better prepared. Even in China, the daily number of new cases has been falling, and the number of people released from hospital rising, which suggests that the disease may already have peaked.

You Decide

  1. If you were offered the holiday of a lifetime in China or Italy starting tomorrow, would you go?
  2. Is under-reporting an epidemic ever justifiable?


  1. Draw a map of the world showing where the most serious outbreaks of the disease have been.
  2. Imagine you are in charge of a cruise ship on which one passenger has contracted the coronavirus. Write a one-page letter to the other passengers explaining why you are not prepared to let them leave the ship.

Some People Say...

“Our reaction to phenomena, such as epidemics or religious war, is not that different to how we reacted to plagues or battles millennia ago.”

Karen Maitland, British novelist

What do you think?

Q & A

What do we know?
What distinguishes the Covid-19 epidemic from other modern medical emergencies is how far it has spread. The Sars and Ebola viruses, though much more likely to be fatal, were restricted to comparatively small areas. Experts are worried not only about the immediate health threat, but the damage to trade and tourism, which some believe could cause a global recession – and that would inevitably mean less money for health care, increasing the chance of Covid-19 doing further damage.
What do we not know?
Whether it is seasonal, like flu, which is more prevalent in winter. We don’t know how long it will take to find a vaccine or cure. Scientists have managed to recreate the virus in a laboratory as a first step, but say that it could take a year or 18 months to come up with a vaccine which has been proved safe and effective.

Word Watch

The World Health Organisation
A branch of the United Nations established in 1948 to improve global healthcare.
The official scientific name for the type of coronavirus now sweeping the world.
An outbreak of disease which occurs across a wide geographic area, as opposed to an epidemic, which is confined to a particular region. The WHO has not yet declared Covid-19 a pandemic.
Severe Acute Respiratory Syndrome, another type of coronavirus.
A highly infectious disease causing internal and external bleeding. A vaccine against it has recently been developed.
A disease which affects the brain and causes confusion and memory loss.


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