Data on deaths from COVID-19 show an association with age that closely matches the “normal” age-related risk of death from all other causes that we all face each year, says statistician David Spiegelhalter in The BMJ today.
His findings are based on analysis of death certificate data for England and Wales over a 16 week (112 day) period between 7 March and 26 June 2020.
For the general population aged over 55, he calculates that the risk of catching and then dying from COVID-19 during this time was equivalent to experiencing around five weeks extra risk above the “normal” annual risk of death.
This risk decreased steadily with age, corresponding to just two additional days above the “normal” annual risk for school children.
For those over 55 who are infected with COVID-19, he suggests that the additional risk of dying is slightly more than the “normal” risk of death from all other causes over one year, and less than this for under 55s.
He shows that the death rate during this 16 week period was around 12-13% higher for each year older, corresponding to doubling for every five to six additional years of age, and this relation is consistent from childhood to old age. One in 50 people over 90 died with COVID-19 over this period, compared to 1 in 2,300,000 schoolchildren aged between 5 and 14.
It is difficult to communicate the huge range of individual mortality risks from COVID-19 experienced by people of different ages, he writes, but explaining risk in terms of the “normal” risk people face could help people understand and manage their response.
He points out that this analysis refers to averages over populations, and although age seems to be the overwhelmingly dominant influence on mortality, clearly other factors, such as pre-existing medical conditions, affect individual risk.
He also stresses that these are observed historical rates in the population and cannot be quoted as the future risks of getting COVID-19 and dying.
Nevertheless, he concludes that normal risk “appears a reasonable comparator for interpreting both population and infection fatality risks, although incorporation in any public facing tool would require careful evaluation, especially in light of the growing concerns about the prolonged impacts of infection.”
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