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So how deadly is it? This question is much more relevant, but less straightforward to answer.

Reports of the virus’s lethality vary by an order of magnitude. While most people manage to recover from COVID-19, a significant proportion succumb to direct viral damage, pneumonia and sepsis.

On March 3 the World Health Organization stated the death rate was 3.4 per cent. Other widely quoted estimates have put the figure at 3.0 per cent or 5.0 per cent. But other sources have estimated it at well under 1.0 per cent.

One reason for these discrepancies is that they often use two different ways to calculate the death rate.

The Case Fatality Rate (CFR) is the number of deaths divided by the number of known infections. This figure can be greatly biased upwards or downwards due to sampling.

Imagine the virus infects 100 people; 70 are asymptomatic and unaware of their infection, while 30 fall sick and are diagnosed, and one of these 30 people dies.

In this example the true death rate is 1.0 per cent (1/100), but the CFR is 3.3 per cent (1/30).

This bias is often strongest during an outbreak’s early stages, when many mild cases are missed and the number of confirmed cases is still low.

For this reason, some epidemiologists now think the initially reported death rates are severe overestimates.

There is a second measure we can use here, which corresponds more closely to most people’s idea of “deadliness.” The Infection Fatality Rate (IFR) is the number of deaths divided by the true number of infections (including both confirmed and undiagnosed cases). This statistic is harder to calculate, as it requires estimating the number of undetected infections.