- 05 Apr 2020 05:50
Why Covid-19 deaths are a substantial over-estimate
John Lee, consultant histopathologist at Rotherham General Hospital and formerly clinical professor of pathology at Hull York Medical School.
Next, what about the deaths? Many UK health spokespersons have been careful to repeatedly say that the numbers quoted in the UK indicate death with the virus, not death due to the virus – this matters. When giving evidence in parliament a few days ago, Prof. Neil Ferguson of Imperial College London said that he now expects fewer than 20,000 Covid-19 deaths in the UK but, importantly, two-thirds of these people would have died anyway. In other words, he suggests that the crude figure for ‘Covid deaths’ is three times higher than the number who have actually been killed by Covid-19. (Even the two-thirds figure is an estimate – it would not surprise me if the real proportion is higher.)
This nuance is crucial – not just in understanding the disease, but for understanding the burden it might place on the health service in coming days. Unfortunately nuance tends to be lost in the numbers quoted from the database being used to track Covid-19: the Johns Hopkins Coronavirus Resource Center. It has compiled a huge database, with Covid-19 data from all over the world, updated daily – and its figures are used, world over, to track the virus. This data is not standardised and so probably not comparable, yet this important caveat is seldom expressed by the (many) graphs we see. It risks exaggerating the quality of data that we have.
The distinction between dying ‘with’ Covid-19 and dying ‘due to’ Covid-19 is not just splitting hairs. Consider some examples: an 87-year-old woman with dementia in a nursing home; a 79-year-old man with metastatic bladder cancer; a 29-year-old man with leukaemia treated with chemotherapy; a 46-year-old woman with motor neurone disease for 2 years. All develop chest infections and die. All test positive for Covid-19. Yet all were vulnerable to death by chest infection from any infective cause (including the flu). Covid-19 might have been the final straw, but it has not caused their deaths. Consider two more cases: a 75-year-old man with mild heart failure and bronchitis; a 35-year-old woman who was previously fit and well with no known medical conditions. Both contract a chest infection and die, and both test positive for Covid-19. In the first case it is not entirely clear what weight to place on the pre-existing conditions versus the viral infection – to make this judgement would require an expert clinician to examine the case notes. The final case would reasonably be attributed to death caused by Covid-19, assuming it was true that there were no underlying conditions.
It should be noted that there is no international standard method for attributing or recording causes of death. Also, normally, most respiratory deaths never have a specific infective cause recorded, whereas at the moment one can expect all positive Covid-19 results associated with a death to be recorded. Again, this is not splitting hairs. Imagine a population where more and more of us have already had Covid-19, and where every ill and dying patient is tested for the virus. The deaths apparently due to Covid-19, the Covid trajectory, will approach the overall death rate. It would appear that all deaths were caused by Covid-19 – would this be true? No. The severity of the epidemic would be indicated by how many extra deaths (above normal) there were overall.
John Lee is a recently retired professor of pathology and a former NHS consultant pathologist.
"only 12% of death certificates have shown a direct causality from coronavirus, while 88% of patients who have died have at least one pre-morbidity - many two or three." - Professor Walter Ricciardi, Director of the Department of Public Health