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Flu has disappeared worldwide during the Covid pandemic

scientificamerican.com

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Re: Flu has disappeared worldwide during the Covid pandemic

#651

Post by Majromax »

darkerside wrote: post #615
Majromax wrote: post #237

This should not come as a surprise, and it was largely predictable from the outset. The flu has a base reproduction number (R0) less than 2 ( https://www.vdh.virginia.gov/coronavirus/2020/12/07/covid-19... ). Covid has an R0 in the vicinity of 2.5 ( https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scena... ). In the meantime, public health measures like masking and distancing will work against both viruses. If…

I'm really excited to see this thread on HN because I've got a question about flu vs COVID, and I feel like this is my only (slim) chance to get a non-politicized answer to it. It's a simple question. Flu deaths in the US have dropped precipitously. This past flu season resulted in (very roughly) ~1% of the deaths of previous seasons. It seems obvious that this is primarily due to social distancing efforts as you say…

> To naive little me, this implies that COVID deaths are also likely to have been reduced to ~1% from what they would have been without said measures.

No, unfortunately this is not true. While the flu season disappeared entirely, covid obviously did not -- it grew significantly. As it stands, the United States has seen just shy of 100,000 confirmed cases per million people; if that represented 1% of a "status quo" infection rate then you'd have to expect everyone in the US to have covid 10 times over.

Instead, you have to think about the logistic model of infectious disease growth. As a very rough back of the envelope calculation, Covid has an R0 of about 2.5. It will spread throughout the population until about 60% is immune/recovered (which roughly matches the critical vaccination level seen in Israel, providing a reasonable check on this number).

That implies that absent public health measures (i.e. where covid quickly spreads to a level that gives herd immunity), the United States would have seen about 200 million cases (330m0.6), or 600,000 cases per million.

What that implies about deaths* depends on your estimates of how comprehensive case identification has been. If you think that we've tested and identified the vast majority of cases, then the "worst case" would be about 6x the current rate of infection and a similar increase in the total death rate. If on the other hand you think we've vastly undercounted cases, then maybe the US has in fact come close to that herd immunity level already, and the public health restrictions only succeeded in "flattening the curve" without changing the cumulative outcome much.

Working at this from another angle, the CDC estimates (https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scena..., case 5) give an infection/fatality ratio of about 0.25% when you apply their demographic estimates to the US population writ large. If you back-fit an estimated number of covid cases from the currently-observed 500,000 deaths, you end up remarkably close to 200m total cases -- but you can also quibble here by noting that seniors' homes suffered a disproportionate share of infections and deaths, especially early in the pandemic.

Re: Flu has disappeared worldwide during the Covid pandemic

#652

Post by Raidion »

JoshuaDavid wrote: post #623
darkerside wrote: post #615

Earlier quoted context omitted.

I'm really excited to see this thread on HN because I've got a question about flu vs COVID, and I feel like this is my only (slim) chance to get a non-politicized answer to it. It's a simple question. Flu deaths in the US have dropped precipitously. This past flu season resulted in (very roughly) ~1% of the deaths of previous seasons. It seems obvious that this is primarily due to social distancing efforts as you say…

32.8 million Americans have had confirmed positive tests for COVID-19 as of April 26[1], and the current US population is 328.2 million, so at a minimum 10% of the people in the US have gotten COVID. A maximum of 100% of the people in the US could be infected[2], so that implies an upper bound of 10x worse or 5M deaths averted by all interventions combined. US CDC estimates that about 3 - 3.5x as many people have con…

There are a bunch of stuff that make this hard to calculate. One is that cases are undercounted, while deaths are almost certainly not. Another is that deaths are correlated to available healthcare. 3x cases would mean that the standard of care goes down, which means more deaths. More deaths would probably also mean increased "protective" measures. Risk tolerance (and risk of infection) is elastic. Seeing 3x more deaths would certainly mean at least some people would take it more seriously, which reduces risky behavior and slows down cases, etc.

So you're right, if worst case everyone in the US gets infected, we're in for a lot more deaths, but aside from an apocalyptical R=100 type disease, not everyone is getting infected. The more infections there are, the more preventative measures are taken, etc.

It's a hard problem.

Re: Flu has disappeared worldwide during the Covid pandemic

#653

Post by javagram »

samatman wrote: post #354
Majromax wrote: post #308

Earlier quoted context omitted.

> and the small difference in R0 is crude thinking. Given the reproduction number appears as the base of an exponent, I would not consider the difference "small." If influenza has a typical R0 of about 2, reducing contacts by 50% would make its growth non-exponential. If covid has a typical R0 of about 2.5, doing the same would require a further 20% reduction of contacts, to 40% of baseline rather than 50%. Since pop…

Small but important correction: nothing can make epidemiological spread non-exponential. Driving base reproduction below one additional infection per infected patient means the exponent is less than one, so the incidence of the disease rapidly decreases. This decrease is also exponential by definition: infection is simply an exponential process, and an exponential equation doesn't stop being what it is when the expon…

> Which will be "fun" because our societies now have a hyperactive immune system, and there will be considerable political pressure to "do something" about the next flu wave.

So, do something by taking a flu vaccine like is already available and recommended for annual use by the CDC?

Re: Flu has disappeared worldwide during the Covid pandemic

#654

Post by awwaiid »

kube-system wrote: post #464
nodamage wrote: post #461

Earlier quoted context omitted.

It's disappointing to see this type of misinformation being spread on HN. All you need to do is look at all-cause mortality in 2020 compared to previous years to easily disprove this: https://i.imgur.com/z9RsQ8e.png

I haven't seen this before, thanks for sharing. Do you know the original source?

Here is the one I look at (might need desktop version), https://www.cdc.gov/nchs/nvss/vsrr/covid19/excess_deaths.htm

Re: Flu has disappeared worldwide during the Covid pandemic

#655

Post by lifeformed »

Majromax wrote: post #237

This should not come as a surprise, and it was largely predictable from the outset. The flu has a base reproduction number (R0) less than 2 ( https://www.vdh.virginia.gov/coronavirus/2020/12/07/covid-19... ). Covid has an R0 in the vicinity of 2.5 ( https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scena... ). In the meantime, public health measures like masking and distancing will work against both viruses. If…

Does this mean the excess death rate is undercounting covid then? Since the baseline death rate is counting normal flu deaths.

Re: Flu has disappeared worldwide during the Covid pandemic

#656

Post by Majromax »

joshuamorton wrote: post #643
timr wrote: post #430

Earlier quoted context omitted.

> Sorry to be harsh here, but that's exactly what I meant by dodging: Parent asked for evidence that the R0 of influenza is higher on average than the R0 of SARS-Cov-2. Burden is on the parent to prove their claim, not for me to disprove claims advanced without evidence. All current estimates for R0 have wide, overlapping confidence intervals that make it impossible to differentiate them from other viruses. The best…

> Burden is on the parent to prove their claim, not for me to disprove claims advanced without evidence. Multiple people have cited many papers that all generally agree with the trend that influenza has a lower r0. You've discounted those by making what are ultimately statistically unsound claims. > I cited just such a paper. Please refer to it The paper you cited supports the other person's contention: that r0 of in…

> The paper you cited supports the other person's contention: that r0 of influenza is lower than that of covid.

As "the other person[1]," I'd like to point out for the sake of accuracy that the paper you mention here does not in fact study covid. While published in February 2020, the "SARS-CoV" it talks about was SARS 1, not the virus behind the current pandemic.

I've taken my prior for covid's R0 from sources such as the CDC (https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scena...), which seem to report a best guess of about 2.5 with some room for variation.

[1] -- Who is also leaving the argument. We've both made our points well enough for others to form their opinion, and I don't think there's much unexplored territory.

Re: Flu has disappeared worldwide during the Covid pandemic

#657

Post by jrek »

jimsmart wrote: post #496
collyw wrote: post #427

Earlier quoted context omitted.

Around Autumn it was subtly mentioned that the UK figures were going to be for flu and covid combined. Before that it was noted that flu was killing more than coronavirus in summer.

Do you have any links to substantiate those claims, please?

You have to understand - it was REAL subtle.

Re: Flu has disappeared worldwide during the Covid pandemic

#658

Post by seattle_spring »

SamBam wrote: post #575
xyzzy21 wrote: post #516

Earlier quoted context omitted.

Or....(and without any conspiracy theories - never mind MOST conspiracy theories of the last 30 years have entirely become true - conspiracy TRUTHS). Everything that was flu was labeled as COVID since doctors, hospitals and medical professions were PAID a bounty on COVID. Multiple this by PCR testing being 99% fraudulent due to high cycle counts which enable cold viruses and even flu viruses to to test positive becau…

> since doctors, hospitals and medical professions were PAID a bounty on COVID. You what? Do you actually believe this? Seriously?

Oh man I gotta figure out how to get my wife backpay for all the bounties she must be owed!

Re: Flu has disappeared worldwide during the Covid pandemic

#659

Post by SV_BubbleTime »

dizzystar wrote: post #650
dcolkitt wrote: post #640

Anybody care to weigh in on something I can't figure out. Last October I had some sort of illness, with severe flu like symptoms. However my nasal swab PCR test, taken 48 hours after symptoms, came back negative. I assumed it was flu, but everything I'm read suggests that flu is virtually unheard of this season. For a standard cold, it seemed to severe (102 F fever, body aches and chills). I also had a strong reactio…

I took the PCR test back in November. I looked up all the data I could and it wasn't really possible find any straight answers, but this is the closest I could come up with: If you test positive, you likely had it and can spread it. If you test negative, there is about a 40% of a false negative, but it also depends on when you were exposed, so you'll end up negative if you are outside the window... post symptom, you…

> and it was bad enough that the testing company lost their contract (whether they were fudging numbers or not is debatable, I can't find any good information on it either)

Ah yea. That happened in California and Florida for sure, probably other places too. In Florida there were two labs specially that were reporting 100% positive for weeks, I don’t care how badly they had it, that wasn’t actually possible.

You probably had it, my personal experience was I got it early and aside from two days of flu symptoms it was gone. Didn’t know until I gave blood months later and had positive antibodies.

Re: Flu has disappeared worldwide during the Covid pandemic

#660

Post by kalleboo »

abunuwas wrote: post #511
timr wrote: post #271

Earlier quoted context omitted.

> This should not come as a surprise, and it was largely predictable from the outset....the flu has a base reproduction number (R0) less than 2....Covid has an R0 in the vicinity of 2.5....In the meantime, public health measures like masking and distancing will work against both viruses....there's really no need for conspiracy theorizing. Assuming that this is due to "masking and distancing" and the small difference…

This makes sense. I've always caught a flu or cold in the tube or in the office, usually from an infected parent. Last year many parents were enjoying a flu-less life while the schools were closed, only to catch it again a week after opening the schools again. I don't have kids, so last year, for the first time in my life, I didn't spend a single day sick.

Dueling anecdotes:

I live in a country where schools have stayed open and our 2 kids have been going to daycare normally throughout the whole pandemic.

Our kids have also been eerily free of colds/flus this winter, after the previous winter where it seemed like they had fevers weekly and so much snot they'd choke on it while asleep.

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