Lethality of SARS-CoV-2 aka COVID

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JMJ

 

[I am waiting on book, but will post this article as-is at the end of October ... and update as necessary]

 

Back in April I was discussing the lethality of SARS-CoV-2 compared with other diseases.

At that point I wrote: 

 For the Spanish Influenza the data is estimated at greater than 2.5% ... see this 2006 NIH article (link)), NIH 1918 Influenza: The Mother of all Pandemics - table below p19 (link), and WHO Pandemic Influenza Risk Management (link).

 Nota Bene: The footnote on the Spanish Flu CFR listed below is that this is for the USA. The world wide data is probably unreliable due to the lack of records.  I'm guessing that the USA data below is more reliable as the US had better records.

(See WHO Graph below)

Side Note: Something  has been bothering me for a while. Why is the American CFR for Spanish Influenza between 2-3% ... it would seem the COVID-19 - while not as bad as H1N1-1918 - it is in the same league.  I will be digging into this more in another article. (Note: Links to a couple of papers that started me down this path: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7318986/ and https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30484-9/fulltext

I have been doing some additional research and decided that it would be beneficial to publish my research and conclusions.

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                            Part 1 Sources of Data                             

McKinsey

 

I first came across this graphic in the early days of the pandemic and thought it was useful.  However, I was thrown off by the scales used to compress the data. I found it useful to provide context vs other diseases, such as the 1918 influenza pandemic.  However, as I dug into the data, it didn't quite jive, so I did some more digging.

WHO Report (page 19)

https://www.who.int/influenza/preparedness/pandemic/GIP_PandemicInfluenzaRiskManagementInterimGuidance_Jun2013.pdf?ua=1

 

 

The scale that McKinsey used and the emergence of some serological studies from Germany set me off in the search for more comparative data.  This table from the a WHO 2013 influenza planning report set me off as the CFR for the 1918 Spanish Flu was estimated to at between 2-3%. This is close that of SARS-CoV-2 in some regions so it caused me to re-evaluate some of my earlier thoughts and ... of course keep digging.  The great thing about the report is that they had references for the CFR!

I have ordered the book cited in #30 and look forward to reading it. 

So here's the reason this finding tweaked my interest.  I had thought that the 1918 epidemic had a much higher CFR - at least on the order of 10%.  If it was indeed 2-3%, then the gap between the Spanish Flu and SARS-CoV-2 is much smaller than originally thought.  Given the devastation created by the 1918 epidemic, it would cast in a much different light the reaction of those responsible for our welfare.

Cited Sources

https://pubmed.ncbi.nlm.nih.gov/17517812/

26. Pandemics of the 20th–21st centuries. Stockholm, European Centre for Disease Prevention and Control. (Available at: http://ecdc.europa.eu/en/healthtopics/pandemic_preparedness/basic_facts/Pages/historical_pandemics.aspx, accessed April 2013.) 

27. Vynnycky E, Trindall A, Mangtani P. Estimates of the reproduction numbers of Spanish influenza using morbidity data. International Journal of Epidemiology, 2007, 36(4):881–889

 28. Jackson C, Vynnycky E, Mangtani P. Estimates of the transmissibility of the 1918 (Hong Kong) influenza pandemic: evidence of increased transmissibility between successive waves. American Journal of Epidemiolog y, 2010, 171(4):465–478. 

29. Miller MA et al. The signature features of influenza pandemics – implications for policy.
New England Journal of Medicine, 2009, 360:2595–2598. 

30. Taubenberger JK, Morens DM. 1918 influenza: the mother of all pandemics. Emerging Infectious Diseases, 2006, 12(1):15–22.

 The MICROBSCOPE

https://www.informationisbeautiful.net/visualizations/the-microbescope-infectious-diseases-in-context/

 The information is beautiful site also had some interesting information and again the lower CFR was present and they provided a gift!  A link to their data along with references, which led me to the WHO table (above) and as I followed the sources, Taubenberger's book popped up a number of times regarding the lethality of the Spanish Flu.  

So I have it on order!

Spanish Influenza in the USA

 So most people have heard about the Spanish Flu Pandemic that raged across the Earth.  I used it as a meter stick for how bad things can get.  We know the COVID's IFR (0.1 to 1%), CFR (2.3%) and how does that compare with Spanish Flu?

There are huge variations in the estimated lethality of Spanish Flu 2.5 to 10% or even 20%. This variation has been noted:

 

Global death rate

How do these estimates compare with the size of the world population at the time? How large was the share who died in the pandemic?

Estimates suggest that the world population in 1918 was 1.8 billion. 

Based on this, the low estimate of 17.4 million deaths by Spreeuwenberg et al. (2018) implies that the Spanish flu killed almost 1% (0.95%) of the world population.⁹

If we rely on the estimate of 50 million deaths published by Johnson and Mueller, it implies that the Spanish flu killed 2.7% of the world population. And if it was in fact higher – 100 million as these authors suggest – then the global death rate would have been 5.4%.¹⁰ 

The world population was growing by around 13 million every year in this period which suggests that the period of the Spanish flu was likely the last time in history when the world population was declining.^{11
Source: The Spanish flu (1918-20): The global impact of the largest influenza pandemic in history}

Here's a good comparison from that article ...

 I am not the only one making comparisons between 1918 and 2020.

Any mortality comparisons between these two pandemics in the United States, 2020 and 1918, must differentiate between totals and rates. The current US population, a little more than 330 million, is more than three times larger than the population in 1918, estimated at 105 million. The 675,000 deaths attributed to the influenza epidemic made up 0.64 percent of the total population, a little more than six in every thousand people. By contrast, the more than 500,000 deaths attributed to COVID-19 make up about 0.15 percent of the total population, or between one and two in every thousand people. If COVID-19 caused deaths at the same rate as the 1918 epidemic, the total would approach two million. Even the disturbing projections of more than to 600,000 deaths by July 1, 2021, would still remain below the rates recorded in the earlier epidemic.

 It is important to recognize that we don’t know precisely how many people died of “Spanish flu.” Measuring influenza deaths is complicated because this disease often contributes to deaths attributed to other primary causes. The Centers for Disease Control and Prevention Pneumonia and Influenza Mortality Surveillance combines two causes into one reporting category. Most reports during the “Spanish flu” anticipated this practice by combining influenza and pneumonia deaths together, thus recognizing that the epidemic produced more deaths than were just attributed to influenza. We see a similar pattern today, as the actual count of pandemic deaths should include far more than those attributed specifically to COVID-19. Source: Measuring Mortality In The Pandemics Of 1918–19 And 2020–21

 

 

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                                     Part 2 Thoughts                              

First I don't know how the Spanish Influenza CFR of  2.5-3% value was arrived at, however the variation in deaths makes this well within the realm of possibility. I look forward to reading Marks and Beatty's book Epidemics (on order), with the goal of understanding how this number is derived.

I also remember reading a report from the 1920's describing the deaths a region of the US and that the CFR was on the order of 2.5%.  So, I am inclined to believe that the CFR >3% may be more accurate than the numbers that could be conflated with deaths due to WW2.

 

                                     Part 3 Conclusions                             

For me, this comparison is useful to put SARS-CoV-2 into the context of treating disease in the 21st century.

The numbers are consistent with SARS-CoV-2 being a significant health emergency, if not on the same level as 1918 when young people were dying in 24hrs, at least on the potential impact on society in terms of deaths.

I wonder how many people would have survived if the 1918 pandemic have been the 2021 pandemic.

P^3

References

• Variations in Case Fatality during the Influenza Epidemic of 1918
• https://www.jstor.org/stable/4576118?seq=1#metadata_info_tab_contents
• Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic
• https://academic.oup.com/aje/article/187/12/2561/5092383
• https://www.contagionlive.com/view/astrazeneca-files-eua-for-the-first-covid-19-antibody-prophylaxis
• https://europepmc.org/article/pmc/pmc7314216
  
• Comparison of Estimated Excess Deaths in New York City During the COVID-19 and 1918 Influenza Pandemics
• https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2769236
• https://jamanetwork.com/searchresults?author=Jeremy+Samuel+Faust&q=Jeremy+Samuel+Faust
  
• Public health interventions and epidemic intensity during the 1918 influenza pandemic
• https://www.pnas.org/content/104/18/7582
• Study Finds 'Comparable' Mortality Rates Between 1918 Influenza, COVID-19 
• https://www.healthleadersmedia.com/covid-19/study-finds-comparable-mortality-rates-between-1918-influenza-covid-19
• Measuring Mortality In The Pandemics Of 1918–19 And 2020–21
• https://www.healthaffairs.org/do/10.1377/hblog20210329.51293/full/
• The Spanish flu (1918-20): The global impact of the largest influenza pandemic in history
• https://ourworldindata.org/spanish-flu-largest-influenza-pandemic-in-history