# But the flu…

Too much write-up to not share here, but someone had asked why we cared about COVID19 deaths right now, considering influenza had around 730k hospitalizations, and 61k deaths.

I’ll take a stab at it. The 730k and 62k look like preliminary estimates of the 2017-2018 flu season in the US. Flu season is October through February, or 5 months. To translate that into a hospital burden, we need to know that mean influenza hospitalization is 5.4 days. That totals 3,942,000 hospital days over what was the highest flu season in the last several years. That amounts to 17,600 hospital days per calendar day.

By comparison, the average COVID19 hospital days is 10 per patient, which is almost double what influenza needs. In the first three weeks of US COVID19 hospitalizations, we had a cumulative 400 hospitalizations. 10 days per hospitalization, so that’s 4000, over 21 days, so 190 hospital days per calendar day. Almost nothing. Who cares, right?

In the fourth week, we had 2200 additional hospitalizations. Ok, that’s something. 2200 times 10 is 22k, divided by 7 days (a generous suppression of the 7th peak day), and we get 3143 hospital days per calendar day. That’s something, but it’s still only a 5th of the flu.

In the fifth week, we had 17,200 additional hospitalizations. That puts us at 24,571 hospital days per calendar day. Again, generously ignoring that the last day in the week is about 4x the first day, we still are 50% over influenza’s peak highest peak week in the last 10 years.

We’re finishing up week 6 on Monday, April 6. On that day, we’ll have 48k cumulative hospitalizations, or 28,200 additional from the prior week. That’s 282,000 additional hospital days committed, or 16x influenza’s highest peak. Any errors in my math or assumptions simply go away at this point.  Even if I’m off by half or double, we have blown past the flu by a gargantual margin.  Also, we have not reached the peak yet for COVID19.

Since we do not have any sort of partial herd immunity, and because its incubation period is about 3x that of the flu, without quarantine or treatment to reduce the serious and mortal cases, this sweeps through the nation in such a way that it does not slow down until we have 60% immunity, a quarter of the nation is sick at one time, and about 9.8 million US citizens die, mostly over the course of 2 months. It’s just more than our system can handle.

Back to the death portion of the influenza equation, the deaths happen over a certain span, such as week 48 to 23 in 2016-2107, or 42 through 22 in 2017/2018. 2017-2018 was a particularly rough year, though 2018-2019 had a longer flu season, week 41 through week 37. 2019-2020 is not fully recorded yet, and will be muddied by COVID10 this year. Either way, flu season is about 32 weeks, with a peak of 12% of the deaths in one week. It’s pretty consistent that way.

That means the worst week in the worst seasonal influenza cycle in the last decade had around 1100 deaths per day for one week, and everything else is an pretty steep, inverted bell curve. COVID deaths happen around day 20, and detection happen around day 12. That means we have 8 days of latency in the statistics.

The simple and accurate way to look at that is to project the death rate ahead by 8 days, and that’s what you will actually have. Anything further, and you might have a big fall off of cases that you cannot see yet. Also, +1 day because the official numbers always report the next day, with the WHO posting at 4am CDT, and JHU posting at 8pm CDT, and some other stats posting at 4pm EDT.  Alternatively, you can look at today’s hospitalization cumulative counts, and that is what your death count will be in 8-9 days.  That’s just how is has aligned, and is not because all of these people die.  As things slow down, that shortcut will no longer apply.

Well, April 2 formal number was 1100 deaths just for that day. We have already reached the peak influenza deaths per day, and our hCOV19 infection rates are still growing by 15% per day, and death rates still growing by 20% per day. That’s compounding, like a bad payday loan. So, we look ahead 8 days, and that’s 48k deaths, with 10k on April 11. That is nine times the peak influenza deaths per day.

Also, the deaths and hospitalizations don’t just suddenly stop. It’s not 10k one day, and zero the next. We’re on board for at least 100k deaths this year from COVID19. That assumes we have no further flare-ups. No new outbreaks. No new hot zones. None of the hospitals overload and have their death rates go up by 2-4x… You know, like NY/NJ/MA area which is already at capacity, and planning for who to refuse service to because they simply do not have beds, equipment, and staff to handle.

Deserving of mention is ventilator days, but that’s about 10 days for both patient types. Influenza is about 60% death from ICU and COVID19 is about 86% death from ICU, but that doesn’t matter so much as the raw numbers above.

What does matter is that if we listened to everyone who said “it doesn’t matter”, or “we’re overreacting”, or “there’s nothing we can do”, or “the flu is worse”, then in about 4 weeks, we will have a single day that had as many new cases and as many new deaths as the entire influenza season combined. At that point, the naysayers would say “Oh golly, why didn’t THEY do something about this!

So, what’s happened is that they have done something about it. They have chosen a reaction level which skirts the edge of how many people will refuse to comply, vs how many people can die without their re-election campaigns being affected. If it were up to the medical experts, then restrictions would have happened weeks earlier.  It’s not unpredictable, nor a surprise.  We knew China was not being forthcoming.  We knew this was coming.  The naysayers simply suppressed mitigation.

The WHO and the CDC are not able to control disaster funds on that level, nor financial packages to help prevent everyone from losing their houses in a lockdown. They also don’t have the authority. They had to wait for the governing bodies to make those decisions, and grant additional power by delegation. Some countries were faster, and better at reacting. We see those with low infection and death rates, and they are still open for business.

Others, who did like us, are suffering pretty heavily right now, many of them simply unable to report how many people died from the disease, because it overwhelmed their systems. We will have to count the deaths, cremations, burials, etc. after the fact, and subtract the normal amount year to year to find the excess deaths. Not every death will be from the disease. Many will be people who could not get medical care, or supplies, or suicides from the stress.

A common argument is “but Italy has an older population” and a variety of other issues. Yes, they do. That accounts for why their death rate is more than double what China’s was (both went into hospital overload). In the unconstrained mode, doubling happens every 2.2 days, so that is really not a good argument.

Some sources for various claims above:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4603361/ – Mechanical ventilation demand estimates for an influenza pandemic

https://www.ncbi.nlm.nih.gov/books/NBK63484/ – Length of hospital stays for the flu

https://www.cdc.gov/flu/about/burden/index.html – Number of deaths per year from the flu in the US

https://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html – pediatric mortality by week, which I’m using as a proxy for all mortality.

If you want to know what the healthcare community is doing to prepare for and handle the hot zones that exist now, and the ones that will sprout up over the next couple of weeks, check out this site:
https://www.elsevier.com/clinical-solutions/covid-19-toolkit

This site is my favorite for easy to understand visualization of the spread of the disease. A straight line 45 degrees up on a log scale means it’s not getting better, and each unit up is 10x the previous unit. Horizontal means no more spread.
http://91-divoc.com/pages/covid-visualization/

If you want to play with the raw data yourself, you can get daily detail reports, as well as tables showing each day in a single row for confirmed cases, and confirmed deaths. Check here for JHU’s data:
https://github.com/CSSEGISandData/COVID-19/tree/master/csse_covid_19_data

Similar data for testing rates, hospitalizations, ICU usage, ventillator usage, etc is here:
https://github.com/COVID19Tracking/covid-tracking-data/tree/master/data

Unfortunately, there is no formal estimate on how many unreported cases there are out there, but it is probably somewhere between 3x and 10x the official counts. That dilutes the relative mortality rates to somewhere around 0.2% and 1.0%, compared to influenza which is somewhere around 0.05% according to the sources above.

EDIT: Fixed hospital-days math, and corrected spelling/grammar.