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Comment by samatman | Hacker News Reader

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 exponent is less than one.

The steady state is exactly 1, which is like balancing a pencil on its point.

It's plausible that two things happened here: the various local restrictions reduced the R0 of flu below 1, and the border closures kept mutations from traveling: and influenza is notoriously mutation-prone.

These can combine to practically extirpate influenza. Unfortunately, the effect is temporary, and the next flu season is likely to be a real doozy.

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. This must be resisted but I'm not optimistic.

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At a super fundamental level, epidemics take place on a social graph. In a well connected graph spread will be exponential, but depending on graph shape it could be something else.

In particular you could imagine that if people never venture outside their own block that the social network is an euclidean graph. In an ideal case where people are evenly spaced in the plane and only interact with neighbors, the disease would spread as a circle expanding outwards, so total infections would be proportional to ~ t^2, and current infections ~ t.

You are essentially describing a supersized plaque assay (https://en.wikipedia.org/wiki/Virus_quantification#Plaque_as...).

I'm perplexed why anyone would downvote this comment; it seems very interesting and insightful to me.

I'm perplexed as well. That the perfect mixing models most people think of for infectious diseases are an imperfect approximation of the actual dynamics on a graph is well known in epidemiology.

> The steady state is exactly 1, which is like balancing a pencil on its point.

At exactly one, it's indeterminate; you could see a subexponential growth or decay. With no exponential terms remaining, lower-order terms that are ordinarily hidden by exponential growth become the dominant observables. (Since epidemic spread is also random, you're much more likely to see the stochastic terms show up in the overall statistics in these cases. You really can be lucky or unlucky with Rt ~= 1, but there's no persistent luck with Rt >> 1.)

This is also important before community spreading sets in, and it is the mechanism by which contact tracing can work. Rather than change the general susceptibility of the population to the disease (changing the effective reproduction number), contact tracing tries to operate at the level of individual cases in ways that cannot be scaled to uncontrolled community spreading (even if Rt is close to 1).

> and the border closures kept mutations from traveling: and influenza is notoriously mutation-prone.

Perhaps, but are influenza mutations an important effect within a single flu season? I know the determination of to-be-dominant strains has a great effect on the composition of each season's flu vaccine, but as far as I am aware we don't see declining flu vaccine efficacy over a season.

By the way, now that we are already talking about R ~= 1 ...

Over pretty much the last year you could observe, in different countries all around the world, that the reproduction number was 'magically' floating around 1.

Only recently did I learn that this effect was puzzling for epidemiologists as well and was only solved around 2012 (?) in a model that assumes a network of information about the disease in parallel to the network of disease transmission. The resulting feedback loops lead to the meta-stability of R=1. Super interesting how society acts as this distributed information processor, similar to 'the market' in economics.

A well-known Norwegian economic commentator pointed this out in a newspaper article a few weeks ago. You'll eventually be forced to maintain an R~=1 no matter what you do, so it's best for everyone if your cases have a low baseline when that happens. The measures will be the same, but the baseline risk can either be terrible or okay.

You can almost see the phenomenon in real time during this pandemic. Countries that have low trust in authorities will still freak out when the epidemic hits biblical proportions, and do various forms of impromptu distancing measures which will bring the R number down. Then when the signs of panic subside, they'll loosen them. And so on.

Societies with high trust in authorities will still pressure their authorities to loosen up when things feel safe, with predictible results, leading to further lockdowns.

The economic deviation caused by governments over reacting is your biggest pressure. Unless you shut down all travel, bars, restaurants, schools, universities and dating.

Then all of this will come back in the future and kick you in the teeth. Either we're going to have to accept this as a way of life, which is more detrimental. Or we're pushing off the inevitable.

No one has overreacted, unless you accept an outcome that both leads to improvised individual social distancing and the even worse worse economic devastation that follows.

This was uncertain to most people last year, but now we’ve seen so many examples that it really shouldn’t be so controversial any longer. But if it wasn’t, we wouldn’t be discussing it.

The covid virus is evolved to fit exactly into the niche of societal behavior where it will be a big fucking problem but not so bad that it’s immediately obvious to enough people.

We're not talking about a single flu season, effectively we're talking about skipping an entire flu season.

Influenza is pretty promiscuous. In normal conditions, very few people aren't exposed to it: either their existing immune resistance (vaccinated or otherwise) is up to the job, or it isn't.

Mutation is therefore the primary driver of flu, year upon year. This is why vaccines are continually reformulated for a best-guess at what strains are going to be dominant.

We had just concluded a northern-hemisphere flu season when travel restrictions started to kick in. This was followed by at least a 90% reduction in international travel, and for most of what remained, it was mandated that new arrivals isolate for long enough to eliminate any influenza they might have carried.

Lockdowns would mean less mutation to begin with, since it happens in human hosts. And such mutations as did present are going to have a tough time jumping oceans, and even when they do arrive, spreading through the populace is substantially inhibited.

Ironically, the universal mask mandates are likely to be more effective against flu than against COVID. Like it or not, masking has minimal effect on spreading aerosols, although using a "real" mask, and being pretty careful to wear it right, can mitigate inhaling those aerosols.

Influenza is believed to be spreadable through aerosols, but the primary vector is droplets, while the opposite appears to be true for SARS2. Bog-standard cloth masks are fairly good at keeping droplets off people and surfaces.

People don't inhale 1 or 0 covid particles they inhale n particles where reducing the value of n makes transmission less likely. Keeping more of your spit to yourself reduces chance of transmission even if masks are imperfect.

> Like it or not, masking has minimal effect on spreading aerosols

[citation needed]

> The overwhelming majority of transmission of SARS-CoV-2 is via large respiratory droplets as conclusively demonstrated by contact tracing studies, cluster investigations, the lack of infection spread in hospital settings with universal masking protocols and the low estimated R.

https://www.pennmedicine.org/updates/blogs/penn-physician-bl...

> The principal mode by which people are infected with SARS-CoV-2 (the virus that causes COVID-19) is through exposure to respiratory droplets carrying infectious virus.

https://www.cdc.gov/coronavirus/2019-ncov/science/science-br...

From what I can tell, you may have your flu/covid mixed up. Covid is spread through respiratory droplets, the spread of which is reduced by wearing a mask.

Both those sources may be out of date now (July and October). While there is limited experimental evidence for airborne transmission except in animals, there is even less evidence for fomite & respiratory droplet transmission.

The claim that "lack of infection spread in hospital settings" rules out airborne transmission due to masking is also questionable. The opposite seems true. As I understand it, infections in hospital settings have been routinely documented throughout the pandemic despite masking, contact protocols, etc. - which implicates airborne rather than droplet/fomite transmission.

This is a really good article in the Lancet recently which solidified my opinion on this. It offers 10 items of evidence for airborne transmission being the primary driver of the pandemic.

https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

For me, the key points are:

> Second, long-range transmission of SARS-CoV-2 between people in adjacent rooms but never in each other's presence has been documented in quarantine hotels.7

> Sixth, viable SARS-CoV-2 has been detected in the air. In laboratory experiments, SARS-CoV-2 stayed infectious in the air for up to 3 h with a half-life of 1·1 h.12 Viable SARS-CoV-2 was identified in air samples from rooms occupied by COVID-19 patients in the absence of aerosol-generating health-care procedures13 and in air samples from an infected person's car.14 Although other studies have failed to capture viable SARS-CoV-2 in air samples, this is to be expected. Sampling of airborne virus is technically challenging for several reasons, including limited effectiveness of some sampling methods for collecting fine particles, viral dehydration during collection, viral damage due to impact forces (leading to loss of viability), reaerosolisation of virus during collection, and viral retention in the sampling equipment.3 Measles and tuberculosis, two primarily airborne diseases, have never been cultivated from room air.15

> Seventh, SARS-CoV-2 has been identified in air filters and building ducts in hospitals with COVID-19 patients; such locations could be reached only by aerosols.16

> Eighth, studies involving infected caged animals that were connected to separately caged uninfected animals via an air duct have shown transmission of SARS-CoV-2 that can be adequately explained only by aerosols.17

> Tenth, there is limited evidence to support other dominant routes of transmission—ie, respiratory droplet or fomite.9, 24 Ease of infection between people in close proximity to each other has been cited as proof of respiratory droplet transmission of SARS-CoV-2. However, close-proximity transmission in most cases along with distant infection for a few when sharing air is more likely to be explained by dilution of exhaled aerosols with distance from an infected person.9 The flawed assumption that transmission through close proximity implies large respiratory droplets or fomites was historically used for decades to deny the airborne transmission of tuberculosis and measles.

>> there will be considerable political pressure to "do something" about the next flu wave. This must be resisted

Why on earth does it make sense to resist sensible public health measures to reduce the influenza to R0<1?

The measures would not need to be nearly as drastic as those for COVID ("normal" R0 of 2 vs 2.5+), so more handwashing (good to minimize a broad spectrum of pathogens), masks (already culturally ordinary in many countries), and especially better indoor ventilation systems would be a long-term benefit to everyone.

I'm mostly hoping that the success of better sequencing, mRNA vaccine technology, and the rapid development deployed for CV-19 will also be applicable to influenza and help minimize or practically eliminate it.

Are you assuming other measures?

"so more handwashing (good to minimize a broad spectrum of pathogens), masks (already culturally ordinary in many countries), and especially better indoor ventilation systems"

Let's not forget a substantial portion of the population working from home, using less public transportation (choosing to travel by car when traveling at all), a huge decrease in tourism and large public gatherings, much less eating out at restaurants, contactless food delivery becoming the norm, etc.

So many factors figure in to why much of the (wealthy, developed) world is a lot more resistant to contagious pathogens today than it was a year ago.

Politicians have shown themselves throughout this pandemic to be opportunistic authoritarians who obviously don't believe in their mandates since they break them themselves so frequently. There's no reason to expect that these sociopaths won't jump at the opportunity to drink more from the fountain of power again given the chance. Since they've gotten away with so much this time, they might even be tempted to go even further next time.

Are you serious?

If anything, politicians have vastly under-managed the situation, timidly afraid of offending constituents' offense at any inconvenience, and only partially at best following sound science.

In states that did issue orders for masks and stay-at-home, the orders were weak, late, and lifted early, resulting in multiple waves that only abate now because of the rapid deployment of vaccines.

Most importantly, there was very little and late funding to cover the costs of those who should most have been shut down, group travel, entertainment, dining, etc. - should have been fully shut down immediately, and everyone's costs covered.

6-10 weeks of hard shutdown, while standing up a full masking, test/trace/isolate protocol would have handled it, yet few countries did it.

A few countries did implement early, strong, and effective measures, such as New Zealand. They also then opened up many months earlier than the rest of the world with near-normal life.

Where are the politicians "drunk with power" who are restarting lockdowns for their own gratification?

Where is the advantage for such a "drunk on power" politician? What could they possible gain by unnecessarily implementing measures that are seen at best by the smart ones who understand it as a necessary inconvenience, and by the rest as an assault on them?

Even flat-out authoritarians do no such thing. E.g., China, who is unashamed to run literal concentration camps for Uyghur minorities, and who did hard lockdowns at the start, is not opening up as soon as scientifically feasible.

Unless you can show some citations of evidence, this looks a lot less like a real phenomenon, and more like a pseudo-libertarian teenager's trope.

This is basically a fantasy. Public health measures that restrict freedom are unpopular even when they are justified. More than anything else your least favorite lawmaker wants to remain employed and to do so they will eventually bow to the will of the people even when the people are ignorant.

Public health measures that you disdain aren't popular where they are because your neighbors want to step on your neck they are popular because people who know more than you do know they on net save lives.

When there is nothing to be gained by such measure support will blow away like dust in the wind. There is no battle for you to fight.

Those measures are not entirely different from the measures previously suggested, though.

Obviously your quoted poster’s concerns are less about “hand washing”, “wear a mask if you have symptoms”, and “stay home” while you recover, and instead are about an overreaction in which entire businesses are forced to shut down, children without symptoms are forced to wear masks even as they run and play, and people are forcibly prevented from leaving their homes “just because it’s flu season”.

This may be necessary, at times, for COVID-19, but as you recognized, not for the normal flu.

Given the spotty record of both public and private policy with regards to using actual science as a driver, these are not invalid concerns.

Or put differently, rather than presuming that anyone against “doing something” is against “common sense” measures, perhaps we should be supportive of making sure that we do something, AND that the “something” that we do remain in the realm of common sense, to assuage the very real concerns that “doing something” could mean something more harmful than good.

The normal flu can be pretty bad. In 2018 the spike in total deaths in TX and surrounding states were between a third and a half of the covid spike in those regions. Masks might have been a good idea in 2018 and I hope they become part of our culture at least when you think you might be coming down with something. You know, that first day of a cold when you are telling yourself its allergies or drainage. Shutting down stores makes less sense.

How about a culture and social support system where you can just stay home and rest if you feel something's up? Probably a lot more efficient than a mask, and would probably help with lots of other problems as well.

Plenty of people, hourly, gig, and self-employed people don’t get paid if they don’t work. You might be able to force some of those to be paid while sick-not-working, but the last category will be very difficult to address without either missing a lot of folks or creating tons of fraud and grift risk (and represent a lot of interactions with the public).

I think this goes under culture and social support system. Perhaps worth a thought that giving more support for everybody can help everybody. This interaction is quite apparent in e.g. epidemics, but probably has similar effects for many phenomena.

Of course it falls into the category of social support system, but what the specific design choices are matter in terms of driving behavior.

If I (salaried) take a sick day, I get paid the same amount from the same source; there’s next-to-no economic incentive for me to risk the health of others by working when sick: problem is solved.

We could more or less force the same by law for scheduled hourly workers. It’s a little more difficult for gig. It’s basically impossible (as I see it) to put self-employed people at the same outcome as if they worked without substantial risks of under-comping some and over-comping others.

It seems pretty clear that the person you’re replying to agrees with you, they just committed the crime of stating your position more succinctly.

Washington state has a tax funded state paid sick leave program for anyone who has worked at least n hours in the prior year and paid into it.

But sometimes it is allergies, and you feel fine and want to get some work done. Masks aren't a big deal, I forget I have mine on, and I wear it all day. Maybe some people have more difficulty? If I vwas in construction or something more physical vthan typing I might vfeel differently.

People who are subject to allergies know they are so and allergies doesn't cause most of the same symptoms. You could probably differentiate most cases of sickness by simply taking your temperature.

I think most people have allergies now don't they? It didn't used to be that way. I get colds with no fever usually.

I think only 1 in 6 or 7 are allergic to anything if you mean seasonal allergies to pollen what most people seem to mean when they say they feel poorly from allergies its only half as prevalent.

That is to say most people don't have allergies to confuse with illness and although you might wake up feeling poorly for a number of reasons flu sufferers are liable to suffer from one or more distinguishable symptoms for example for myself when I've contracted the flu I always get a really shitty body ache.

It's possible to get a cold without also having a fever. You are absolutely correct about that but even in that instance the majority are liable to be able to know when they are ill. They just don't stay home because the social pressure has been in favor of bringing your sickness to work as if you were doing everyone a favor by showing up and making your cohorts sick.

When I was a kid with allergies I think it was 15% had allergies. Now 30% of adults and 40% of kids have them. https://www.webmd.com/allergies/allergy-statistics

Sometimes my throat is sore but its just allergy drainage. It doesn't help that the things I'm allergic to line up with flu season.

7.8% of Adults suffer from hay fever. *1 Around 50 million out of around 330 or about 15% suffer from any sort of allergies according to the AAAAI *2 which references data from the CDC

https://www.aaaai.org/about-aaaai/newsroom/allergy-statistic...

https://acaai.org/news/facts-statistics/allergies

1 Hay fever, or allergic rhinitis, is a common condition with symptoms similar to those of a cold. There may be sneezing, congestion, runny nose, and sinus pressure. It is caused by an allergic response to airborne substances, such as pollen.

2 The American Academy of Allergy, Asthma & Immunology (AAAAI) is the most prominent membership organization of more than 7,000 allergists / immunologists (in the United States, Canada and 72 other countries) and patients' trusted resource for allergies, asthma and immune deficiency disorders. This membership includes allergist / immunologists, other medical specialists, allied health and related healthcare professionals—all with a special interest in the research and treatment of allergic and immunologic diseases.

WebMD's doesn't actually seem to actually source their data at all despite styling it like a link for some reason and since their is a disparity between what the CDC and AAAAI say I strongly suspect they are full of shit

I only think I have very occasional allergies by observing my health during the pandemic. I have no clue what it's from. I just assumed they were colds before, though I certainly had less illness of any kind this last year.

"Shutting down stores makes less sense."

Depends on what you want to achieve. If you like a increase of infection, you do it like here in germany and close down hardware stores etc. multiple times on short notice, without telling when they will open again - so people try to storm them before they close, all coming closely together by doing so, which they would not have otherwise.

This particular type of unintended consequence has been repeated multiple times during the crisis, it's puzzling.

For example here in order to avoid contamination in public transports they limited the hours of service. Consequence: same number of people took transport but in less time, increasing density and contact.

Similarly with the curfew forcing shops to close earlier in the day, more people gather in less time.

Most of the measures the public health community is pushing are:

- Paid sick leave. First and foremost.

- Increased flexibility for people WFH as possible if sick or vulnerable.

That's really about it. Maybe masking, though that well has been throughly poisoned.

We will be lucky if we can normalize washing your hands more and staying home when you are sick. The idea that we are going to react to flu with fanatical zeal and need to prepare to resist public health measures is a fantasy promoted by those who are preparing to fight a war that exists only in their own heads.

We've had, in the past year, at various times, public policies that have prevented grocery stores from selling "non-essential" items such as towels and blankets (while allowing alcohol), halted critical health services such as cancer treatments, and led to people from the same household being verbally and physically assaulted for not distancing or wearing masks - after a period of time in which people were verbally chastised for wearing masks when the official stance was not to.

We've sorted a lot of this out over the past year, but there is an all time distrust of institutions surrounding both policymakers and the public health recommendations informing them, and there's a reason for it.

We can either help assuage people's fears (whether you see them as founded or unfounded) by empathizing with their concerns and experiences and addressing them while ensuring that any measures enacted remain rooted in science that we can trust...

OR we can be part of the problem for why there's so much distrust, by ignoring anyone who may have real experiences that have caused them to lose trust in our science and health institutions, and telling them that it's all in their head.

I strongly hope for the former, myself.

OR we can shutdown social media. A lot of the misinformation has been spread through social media - it has a tendency to amplify extremism by providing 'echo chambers' people can select into to reinforce their preconceptions.

> children without symptoms are forced to wear masks even as they run and play

Well, yeah, they can be asymptomatic, spread their sickness to other kids, who then take it home to their parents and grandparents.

Agreed. There seem to be too many folks frantically "doing something" these days. The road to hell is paved with good intentions.

>>Small but important correction: nothing can make epidemiological spread non-exponential.

“Exponential with R varying over time” and “not exponential” differ only in interpretation imposed by an observer.

> infection is simply an exponential process

No, in the hyperidealized perfect mixing scenario, its a logistic process, like most other resource constrained processed that look exponential when analyzed over a dhort period.

In the real world, its neither exponential nor even perfectly logistic, even before considering changes to the environment in which the disease spreads (including those induced by the disease, including people’s response to knowledge of it.)

> 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?

The flu vaccine isn't hugely effective at the best of times, and with flu disappearing worldwide and global travel locked down I don't see how they'll even be able to figure out what strains to target for the next one.

Even when not perfectly matched, the flu vaccine does offer some protection.

Both @makomk and @enkid seem to be right [0].

[0] https://www.cochrane.org/CD001269/ARI_vaccines-prevent-influ...

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