Thursday, March 26, 2020

COVID-19 vs Flu

Many people keep trying to compare the coronavirus to the flu.   Here's a quick post to show why you shouldn't do that.

While many of the symptoms are similar for both, that does not make them comparable.  Especially when comparing death rates.

COVID-19 is the name of the coronavirus strain.
The flu is many different strains including H1N1, H3N2, H3N2v, Victoria Lineage, Yamagata Lineage just to list some major ones for this past season.

Thus you can't just lump all the flu deaths as one and then compare it to just one strain of coronavirus.  It just doesn't make sense to do so.  Here is a graph showing positive specimens collected from US Public Health Laboratories:


The other that makes COVID-19 different from those the flu is that we have vaccines for various strains of the flu.  We don't have a vaccine for COVID-19 yet.  This is what is concerning about the current pandemic.  Without any herd immunity at all, the spread of COVID-19 will cause deaths that we can't prevent yet.   Many deaths from the flu are people who are not vaccinated.  For example 80%  of children deaths in the 2017-18 season were not vaccinated.  Many of those could've been preventable. (https://www.cdc.gov/flu/about/season/flu-season-2017-2018.htm ).   Again, without a vaccine, COVID-19 is a growing concern as it becomes more widespread.  This is why we are practicing social distancing and diligent hand washing.  As you can see in the USA, the number of confirmed cases has sharply risen in just 10 days.


One also has to consider the difference between estimated deaths and incremental deaths. Both have different levels of accuracy, precision and meaning. Worldometers.info for example shows incremental (deaths as they are reported) for COVID19. Incremental data will not be absolutely accurate because not every single case will be detected (i.e. those who die at home or those whose cause of death can't be accurately attributed on the day of death). Thus the actual numbers will be higher than reported. Incremental data though is more precise than estimated.

Estimated is probably closer to that actual number (as estimated is retroactive) but it has a wider range of error as it cannot be precise. So both data sets can be helpful in understanding an issue. To compare estimated deaths of flu to incremental deaths of COVID-19 becomes obviously problematic then.

If we take the Diamond Princess cruise ship as a closed system example, it gives us more complete data. "For this outbreak, the case fatality rate as of late April 2020 was 1.8% (13 deaths out of 712 cases); age adjusted to reflect the general population, the figure would have been closer to 0.5%. A case fatality rate of 0.5% would still be 5 times the commonly cited case fatality rate of adult seasonal influenza." https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2766121

As always, make sure to get your info from verified sources (WHO, CDC, Health Canada, etc) as these will give you the most accurate information you will need to make decisions.

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