AAccording to the BBC, on October 15, the Prime Minister sent a WhatsApp message: “I have to say that I was shaken by some of the data on the deaths of Covid. The median age is 82 to 81 for men, 85 for women. It is above life expectancy. So catch Covid and live longer. Presumably, it was a joke, but why is the reasoning so wrong?
First, more technically, the message confuses two types of averages. As children learn in school, the median means that if you line up women based on the age at which they died from Covid-19, the woman in the middle would be 85. But life expectancy is an average – you figure out how long, say, 100,000 newborns are likely to live by assuming the current death rates hold up, add them up and divide them by 100,000. UK data for 2017-19, life expectancy at birth is 79 for males and 83 for females, but the median age at death is slightly higher: 81 for males and 85 for women, the same as that cited for Covid-19.
So why do recorded deaths involving Covid have a similar median age to deaths from other causes? Essentially, the risk factors for dying with Covid are remarkably similar to those for dying from something else – this bullying virus amplifies vulnerabilities and therefore acts pretty much as an underlying fatal risk multiplier.
Most importantly, your life expectancy improves with age. Once a man turns 79, his life expectancy increases: to around 88, or nine years longer. Fortunately, your death continues to overtake you, and reaching the life expectancy you had when you were born does not mean you are on the verge of breaking out of this death spiral. The average man reaching his 98th birthday can expect to live beyond 100 years.
The Health Foundation has estimated an average of 10 years of life lost for each death from Covid-19, with a similar figure for the United States, even taking into account pre-existing health problems. The deaths of Covid-19 were therefore not at the brink of death.
Get Covid-19 and Live Longer? Unfortunately not.
David Spiegelhalter is President of the Winton Center for Risk and Evidence Communication in Cambridge. Anthony Masters is Statistical Ambassador of the Royal Statistical Society