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expert reaction to ONS data comparing COVID-19 to flu and pneumonia as a cause of death

The Office for National Statistics (ONS) has published an article exploring how COVID-19 compares to flu and pneumonia as a cause of death.


Dr Adam Jacobs, Senior Director of Biostatistics at Premier Research, said:

“One thing which is quite important here for any journalists to understand is that there is a really big difference between “deaths due to flu/pneumonia” and “deaths due to flu”.  Lumping flu and pneumonia together in that way obscures a lot of detail, mainly because, although when flu is fatal it’s very often the resulting pneumonia that kills you, there are a great many deaths from pneumonia that are nothing to do with flu.  Pneumonia is quite a common “last straw” that finishes off frail elderly people with a variety of different underlying health conditions.”


Dr Stephen Griffin, Associate Professor in the School of Medicine, University of Leeds, said:

“The constant comparison between seasonal influenza and SARS-CoV2 is a source of frustration and exasperation.  This is clearly borne out by this important analysis.  Influenza is not to be underestimated, but the novel exposure of humans to SARS2 sets this apart from other viruses that are circulating.  Naturally, a pandemic influenza would raise many of the same concerns and impacts as we have seen since 2020.

“Disease is a product of virulence (the capacity of a microorganism to cause harm), immunity (ideally via vaccines, but also prior exposure) and environment.  Thus, the infection fatality ratio (IFR, or case CFR where confirmed by testing) can vary on the population level if a disease has been with a population for some time, disease is worst in older, immunocompromised and societally disadvantaged populations.

“IFR/CFR also need to be factored alongside both prevalence (the number of infections over time) and the total time people are exposed.  Of course, these remain dynamic properties for most, as highlighted by the ability of omicron SARS2 to overcome antibody immunity.

“Hence, the overall clinical impact of a disease with a relatively low IFR but massive prevalence can be far higher than the opposite scenario…a colleague once made the comparison of a mass shooting using a submachine gun versus a sniper rifle.

“Then, there is also the matter of the contribution made by the agent in question to mortality, i.e. whether it is the underlying cause or a contributing factor.  Death certification is a complex, tightly regulated process.  Those slinging mud at this institution in an attempt to minimise the pandemic are in incredibly tenuous and dangerous territory.

“Accordingly, influenza accounts for relatively few deaths as the underlying cause, but the frequent complication of secondary bacterial pneumonia leads to profound clinical impact.

“By contrast, the majority of COVID deaths listed SARS2 as the underlying cause.  This is thankfully reducing because of widespread vaccination, but still accounts for hundreds of deaths every week just in the UK.

“Thus, whilst I balk virologically at the direct comparison between SARS2 and influenza, comparing the clinical impact and resultant strain upon the NHS is reasonable, apart from one critical element.

“Simply put, the hazard of death from any given illness is naturally only relevant if you contract it.  The very high transmissibility of SARS2, especially Omicron, compared to seasonal influenza led to the latter being essentially eliminated during 2020/21 (i.e. the lack of community transmission) whilst the former was barely held in check by all but the harshest protection measures.  Indeed, one particular lineage of influenza B is now thought to potentially be extinct.

“We should also remember that morbidity takes a massive toll upon our population, especially wrt long COVID; death is not the only metric.

“Hence, countries such as Belgium are mandating minimum safety standards for the ventilation of public buildings as well as other measures to complement their already successful, albeit still incomplete vaccination programme.

“Sadly, the UK has not embraced the opportunity to safeguard its citizens in public spaces, its children in schools, or the longevity of the vaccination programme in this way.  Clearly, such measures would also greatly mitigate the impact of other diseases.  Better ventilation also improves cognition by reducing carbon dioxide levels and, along with filtration, can reduce the impact of e.g. pollen and other allergies.

“Thus, whilst I don’t believe we will be able to directly compare SARS2 with seasonal influenza for some years yet, the clinical impact of both should not be underestimated.  The lack of mitigations and protections is a grave concern, and independent SAGE have launched their COVID safety pledge to garner support for safer working, educational and public environments.

“To leave the “living with” strategy, whether applied to flu or SARS2, to a combination of personal choices, vaccines, and limited antivirals (the last two being brilliant, but not infallible) is unwise at best.  We have missed an opportunity to genuinely reduce clinical burden, make reasonable adjustments for clinically vulnerable people and avoid further unforeseen consequences of repeated infections with what remains a novel virus.”


Prof Rowland Kao, the Sir Timothy O’Shea Professor of Veterinary Epidemiology and Data Science, University of Edinburgh, said:

“This report comparing deaths due to COVID-19 compared to flu and pneumonia, highlights the substantial impact that physical distancing measures and vaccination have had on seasonal flu which in both the previous years were substantially lower than previously.  These figures are particularly important, as the recording of deaths tends to be more reliable than for cases, which are more difficult to interpret due to the dependence of case numbers on voluntary reporting.  That COVID-19 deaths were both greater in number and affected a broader range of ages highlights just how much more lethal COVID had been, especially when one considers the broader rollout of COVID vaccination across all adult age groups.  It is however, difficult to tell what this means for the future, where the absence of physical distancing measures and the likely reduction in COVID vaccine booster coverage, and likely lower flu vaccine coverage will mean that future mortality is difficult to predict.  As well, indirect effects of the pandemic on health as well as other stresses on individual health (where pre-existing health conditions and deprivation are known risk factors for more severe COVID outcomes) may result in higher health burdens and relatively high mortality due to both COVID and flu.”


Prof Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said:

“I think the heading should have been how COVID-19 ‘compared’, rather than ‘compares’ to flu, as this is a look at past data.  Data collected from March 2020 includes consequences of infections in a totally naive population as well as data collected after immunity started to build, mainly through vaccination but also from natural infection.  What this doesn’t do is tell us about how COVID and flu will compare in future.

“Future toll will depend on the transmissibility and disease potential of the two viruses set against the protection offered by vaccines and treatments.  Vaccines for flu have improved over the past few years – vaccines for COVID are already proving to be some of the best performing vaccines known.  The only thing likely to massively impact on either is the emergence of a very different variant, and this is always going to be difficult to predict – for both influenza and SARS2.”



All our previous output on this subject can be seen at this weblink:



Declared interests

Dr Stephen Griffin: “Member of Independent SAGE.”

No others received.


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