The Covid-19 pandemic has introduced us to many unfamiliar new terms, like social distancing and deconfinement. Another is excess mortality.
Excess mortality is a calculation that often comes up in the aftermath of a heatwave or a flu epidemic, and describes the number of deaths resulting from that event, minus the number of deaths that would be expected at that time of year in normal circumstances.
The result is the number of deaths that may be presumed to have been a result of the event in question.
In Belgium the peak of excess mortality came on Friday April 10, when a total of 674 people died, all causes included. That compares to 303 at the same time in 2019, resulting in an excess mortality of 371. The figure published by the health institute Sciensano for that day was 318 deaths reported to be a result of Covid-19, although daily reported figures in that period were less than perfectly accurate.
Now the country is, it appears, at the beginning of a second wave of the epidemic, but deaths are not going up. In fact, the number of deaths in July so far is lower than it has been in any of the three preceding years. On July 6, 209 people died, all causes included. In 2019 on that day the total was 281. One Covid-19 death was recorded on that day this year.
So why is the excess of deaths being followed by what might be called a mortality deficit? The answer lies in what demographers refer to as the harvesting effect.
Put rather bluntly, this states that an increase in mortality during a period of time should be followed by a lower than average mortality, because those who were fatally affected by the initial event – in this case the first wave of Covid-19 – were people whose health was already compromised to the extent that had they not died when they did, they would probably have died soon after.
Sure enough, by far the largest group of people who died in the initial phase of the epidemic – more than half of all fatalities – were residents of care homes. In those homes, medical care was not up to the standard of hospitals, staff were less well equipped, and serious cases were not being transferred to hospital.
Of a total of 9,817 deaths, 3,470 were over the age of 85, and another 2,188 aged 75-84. No age data is available for 2,660 more deaths, of which a large portion may be assumed to have been care home residents, who were the only section of the population, a handful of cases excepted, who died outside of hospital.