From Stephen Watkins, retired Director of Public Health, Stockport.

Based on 119 deaths in a patient-facing workforce of about 800,000, the Health Service Journal (HSJ) suggests that death rates in NHS staff are no higher than in the general population.

It is important to remember the difference between mortality rate (deaths per 100,000 people at risk) and fatality rate (proportion of deaths in those actually infected).

It is not possible to draw an accurate conclusion without age-specific mortality rates (not fatality rates) for the general population and for NHS patient facing staff. The crude mortality rate for NHS staff based on the HSJ figures would seem to be about 14 per 100,000 per current duration of epidemic. (“Crude” means not adjusted for age and sex).

Based on the Lancet article by Verity et al[1], the age-specific fatality rates in people of working age, based mainly on Chinese figures, appear to be between 0.03% in people aged 20-29 and 0.59% in people aged 50-59, then increasing to 1.93% in people aged 60-69. Assuming a reasonably even spread of ages between 20 and 65 the average would be 0.3%.

Applying this to the 14 per 100,000 mortality rate would equate to 4,666 cases per 100,000.

Therefore assuming the accuracy of the Chinese fatality rates, and assuming an even spread of ages between 20 and 65 in the NHS workforce, the mortality rate in the NHS population is what would be expected if the death rates were the same as the general population if 4.6% of the working age population has been infected to date.

If fewer than 4.6% of the working age population has so far been infected, the rates in NHS staff are higher. If more than 4.6% of the working age population has so far been infected,  the rates in NHS staff are lower. We do not however have accurate age-specific incidence rates for the general population from which to make an accurate assessment.

However, if there were a 4.6% incidence rate in the general population there would now have been 2,990,000 cases and the Government is not quoting anything like that figure.

Subject to caveats about the inaccuracy of the data and the extreme approximations made in the calculation, it would appear that rates in NHS staff are significantly higher than in the general population. This may, however, not be true if the rates of infection in the general population are being grossly understated, which could well be the case.

[1] Robert Verity et al, “Estimates of the severity of coronavirus disease 2019: a model-based analysis”, The Lancet online 30. 03.20.

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