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There is no such thing as a mild (unmitigated) pandemic

by: SusanC

Mon Apr 30, 2007 at 01:35:43 AM EDT


( - promoted by AnnieB)

SusanC :: There is no such thing as a mild (unmitigated) pandemic
This diary is inspired by lugon, who said yesterday that he refuses to call any pandemic `mild'.  Let's see if you agree with him.

I'm going to take the lowest end of the figures used in the UK pandemic plans, 25% AR occurring over the first wave and 0.4% CFR, and see what this means for a city like London.

Inner London has a population of 7.4M (National Statistics 2004).  A pandemic with 25% AR and 0.4% CFR would mean 7400 deaths over a 15 week period (still using figures from UK plans). 

The last mass casualty event that happened in London was the bombings in the London Underground on 7 July 2005 which killed 52 people.  7400 deaths would be the equivalent of 142 bombings, happening over a 15 week period, or just under 10 a week.

Of course, in reality these deaths would not be evenly distributed over 15 weeks, but more-or-less follow the epidemic curve, such that the weekly rate of accumulation of deaths would look something like this: 7, 22, 81, 310, 1095, 2694 and so on.

As you look at those figures, at which point do you think the people of London will stop going to work to avoid infection?  At which point would parents pull their kids out of school?  At which point would supplies run out because too many people did not turn up for work while at the same time everyone is buying more in anticipation of shortages?  At which point would the public start blaming the government for failing to warn them? 

At which point would looting (of closed shops), rioting, or at least general vandalism happen?

At which point would the London Stock Exchange suspend trading because of staff absences, extreme volatility of trading, failures in payment systems, or grid failure?

Let's look at the impact on health services.  Still using this same scenario, at the peak 2 weeks (weeks 6 & 7), there would be approximately 1600 people dying per week, which is the equivalent of 31 London bombings per week or 4.5 per day.  Can the health services deal with an emergency where the number of deaths is 4 ½ times that of the last mass casualty event, except that it's happening day after day, and at a time when the staff sickness rate would have at least equaled if not surpassed the attack rate of the general population, assuming none of them have gone AWOL? 

Now let's take a look at what such a pandemic would mean at a global level.  25% AR and 0.4% CFR for 6.6 billion people works out at 6.6 million deaths.  The last biggest mass casualty event globally was the tsunami in December 2004, which killed 280,000 people.  Assuming it takes about 6 months for the first wave to cover all parts of the world, 6.6 million deaths is the equivalent of 24 tsunamis over that period, or 4 tsunamis per month each covering a region the size of say 3-4 countries the size of UK.

About 2.9 million people died of AIDS in 2006, of which 2.1 million occurred in sub-Saharan Africa.  The devastation to this region is profound, but has had minimal effect on the rest of the world because this is one of the poorest regions in the world and it's share of global trade is minuscule.  But influenza is a very different disease; it can devastate rich as well as poor countries.  If the next pandemic, as with previous ones, exhibits variations in severity in different parts of the world, what are the chances that those cities that are faring a lot worse than London (described above) would include at least some of the ports crucial for world shipping, such as Hong Kong (world rank #1), Vancouver (Canada rank #1), Long Beach, CA (US rank #5), or Rotterdam (world rank #2)?

There is no such thing as a mild (unmitigated) pandemic.

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Agree, SusanC
Thanks for quantifying the impact of a "mild" pandemic.  I don't see how it could be easy, when it finally hits.  No matter what.

The problem is - memory is short
and when we point out to people that there were two pandemics in the fifties and sixties they just don't remember them. It works againt us, because they think 'I don't remember the last two pandemics, they can't be that terrible'.

Most people assign the title flu to any old cold or noro virus they've had, so they don't think flu is that traumatic. Yes people die, but it's old people isn't it? I'm healthy so I'll be fine. That's what the vast majority think about a 'mild' pandemic. It's where the business as usual thinking comes from.

I've had some success recently asking people to recount their worst flu experience (so there's a fighting chance they are actually thinking of influenza). I then ask them what lengths they might have gone to to avoid catching it. I point out, that unlike seasonal flu where usually very few people catch it, a pandemic could affect half the population.


"this year's flu is worse than last year's" usually means "last year it was a cold, NOW it's flu"


You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.

[ Parent ]
actually...
"this year's flu is worse than last year's" usually means the speaker (or someone in their family) caught it this year and not last year.

[ Parent ]
yep - "folk definition of flu" is not very precise - so
maybe we need to include that somehow in "ExplainingFlues" (wikipage). :-?

It looks like a minor thing - to us.

You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.


[ Parent ]
I'm reading over my notes
from the various meetings I went to in DC.  In the discussions on NPI's, there were these warnings that we must be careful that we won't create consequences from school closure etc that would be more painful than the pandemic itself.

When I look at these low-CFR (hat-tip to lugon again!) scenarios, it would be quite hard to imagine planned co-ordinated uniform school closure for 4 weeks (using current CDC guidelines for CFR < 1%) would be more painful than what I've described.



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


see article from Alabama
A doomsday scenario of a flu pandemic that might never happen is driving a sweeping review of what states should do to minimize the potential impact.

Closing schools has been determined to be one of the best defenses to slow the spread of a flu outbreak, but the implications of long-term school closings are staggering. A flu outbreak of huge proportions would force school doors shut for weeks, if not months.

School administrators, health officials, law enforcement officers and business executives gathered recently to discuss how to handle closing schools for such an extended time. They also received a lesson on the realities of a flu pandemic.

http://www.al.com/ne...


[ Parent ]
I spent till late last night
stuffing envelopes for my school board candidacy.  I've talked to too many people around here who say they won't allow a spouse to pull kids from school if pandemic begins before schools are officially closed.  They think the fears are overblown.  I do not feel comfortable with taking the chance that individual decisions will be made prudently.  The parents who resist the idea of closure during a pandemic have given me the objection that it is not because they feel it will create undue economic hardship, but because the pandemic they see coming they figure will not be too much worse than a regular flu season, for some reason.  ;-(

The only way around that is to become a part of the team that's going to make that decision.  I don't know if my own candidacy will be successful - I haven't lived here too long, and know people only through the local elementary school.  But it's worth a shot. 

I'd encourage anyone else to try to do the same for their community.  If you don't see a BOE opening happening in the near future, then at least make a point of attending Board meetings and bring this issue to their attention in whatever ways seem feasible.  As SusanC pointed out, closing schools is likely going to be the lesser evil of the available choices, by a great margin. We need to make it clear to people how true this is.


[ Parent ]
"not much worse than regular flu"
we need a picture with "gradients"

- regular flu has x1% without symptoms, x2% with mild symptoms, x3% severe, x4% dead
- avian flu also four groups
- previous pandemics same four groups
- next pandemic unknown groups

People have a hard time imagining this.  For me, the Pandemic Severity Index brought much needed light because now we can have, all in one picture, the several posibilities.  We need the same for individual outcomes.

Do we have some data on this?

You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.


[ Parent ]
i mean same groups, very different percentages


You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.

[ Parent ]
tell that to the Indonesian parents! n/t




All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
see this and put all the flus on the same graph




[ Parent ]
Dem, the 3 pandemix *in the same graphic* would be great for ...
this introductory presentation  http://www.fluwikie.... which in turn would be useful for this "let's talk then listen" kind of presentation http://newfluwiki2.c...

You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.

[ Parent ]
I'll give it a shot tonight... n/t


[ Parent ]
better still if the figures are per million people or per 10 million or whatever - then people can multiply or divide as needed - and thanks!


You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.

[ Parent ]
Are these graphs somewhere else so I can print them?
Saving it on my Mac saved the entire diary.  Thanks!

"The truth does not change according to our ability to stomach it."  Flannery O'Connor

[ Parent ]
on a Mac
hit control click and "save" picture. You can "view picture" first if you'd like.

[ Parent ]
I am attending my local town BoE tonight
and the city I work in next week. Both BoEs have panflu on the agenda.

I am using this simple handout.

http://www.newfluwik...


[ Parent ]
Cool!
A picture is worth a thousand words.

I guess that will save you like a couple of them...?  LOL

Good luck with the meeting!



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
How did it go?
I have friends in those towns, and they have kids.  ;-)

[ Parent ]
Good for you Pixie!


[ Parent ]
Legaly required to meet SOL standards
Pixi,

  Just re-read your post and it may be an up-hill battle.

  Schools are required to teach X number of day - typicaly 180. After a bad storm closed schools in my area for a week they added 15 min to the school day. They said "we meet our oblicagation to teach 180 days."

  Also, to maintain school accredidation the students must pass tests. To be successful the schools scores must improve.

  The short of it is I agree with you. The schools have to balence student safety against "a known threat." Hmm, if only a few people are sick then that is not a pandemic - is it? Shedding of germs, what sheeding of germs. I do not see any. The school is very clean.

  I am not defending the school, just voicing what I think they will say or do - IMHO. It is just an opinion.

  Good luck. I just dropped a bunch of Pandemic Flu stuff from the CDC off at my vets and once again got the "Well thank you." Even the "We only have 25 more shopping days till hurricane season - June 1st" joke was not well received.

Kobie


[ Parent ]
school closures are reversible
If you find that the pandemic is milder than anticipated, or evidence that other communities that didn't close schools fared better, you can always re-open them.

So, let me highlight this point ;-)

School closures are reversible.  Deaths are not!




All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
Autopsy study supports link between flu, heart attacks
Autopsy study supports link between flu, heart attacks

Influenza's role as a trigger
Madjid and some other researchers believe that influenza causes severe inflammation that, in some patients, can destabilize atherosclerotic plaques in coronary arteries, which can lead to an AMI, according to the EHJ release.

Most people in Western countries have varying degrees of atherosclerosis, though most will never show any clinical signs of it, Madjid said. "However, in some patients the quiescent, stable atherosclerotic plaques undergo sudden changes, mainly due to exaggerated inflammation, leading to rupture of these vulnerable plaques and subsequent formation of clots resulting in heart attacks," he said.

http://www.cidrap.um...

Comment: The above article relates to autopsies of victims who died from "regular" flu. What this means to me is that this time, there will be no "mild" flu pandemic, as atherosclerosis is widespread.

"Never try to teach a pig to sing.  It frustrates you and annoys the pig." Mark Twain


...
strictly imho - docs may weigh in..  seems like if folks have an existing disease process, ie, CAD, COPD, etc, any impact to the pts ability to exchange air might also further reduce oxygenation of the heart muscle, increasing irritability.

[ Parent ]
note, however
that there's a seasonal influenza outbreak each year.

36K excess deaths a year (250-500K worldwide) result. Some of those may be from the proposed mechanism.


[ Parent ]
But what about hidden flu deaths among heart-attack fatalities?
I agree, Dem, but what has me scratching my head is the insidious way the "regular" flu has killed the victims mentioned in the study.  Some of them had atherosclerosis and didn't know it.  How many heart attack death statistics are really due to the flu?  Could flu fatalities be grossly under-represented in the mortality statistics?  It would also be interesting to find out if atherosclerosis was as widespread a problem back in the '50s and '60s (last 2 pandemics) as it is now.  I'd be inclined to say it wasn't (due to our reliance on fast food and generally poorer diet).  If that is the case, would an otherwise "mild" pandemic provide the ignition for widespread heart attacks?  Further, I'm wondering in light of this recent study if this explains why statins improve one's chances of surviving an H5N1 infection.  Perhaps it has to due with stabilizing the plaque in the arteries, among other things.

"Never try to teach a pig to sing.  It frustrates you and annoys the pig." Mark Twain

[ Parent ]
Really excellent analysis, SusanC
I wish the Times of London would pick it up.

ask and you shall receive
I just sent them the link.  Whether they will pick it up is a different story...



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
Disagree, with respect. What would you call 1957? 1968?
Neither 1957 or 1968 produced the kind of impact you envision that I am aware. 

While reliance on high tech and a global JIT delivery systems would create significant differences bewteen today and 1918, the differences are less extreme when we compare today and 1957 or 1968.

We have had 'mild' pandemics.  1957 had a total death rate of about 3/100 of 1%. (Global Dead 1 Million ; 1957 total population of 2.94 Billion).  If you assume a 30% attack rate, 1957 would have just a shade under 1/10 of 1% (.1%) CFR.  If you adjust for population increase - a 1957 pandemic would kill about 2.24 Million globally today.)  This is a CAT 1 pandemic according to the PSI scale.*

The 1968 pandemic (mildest in that century) had a somewhat lower death rate (US totals for 1957 were 60,000 dead, 1968 were 40,000.) So, 1968 was also a CAT 1 pandemic.

The rub comes when folks assume that a 'mild' pandemic is anything less than a 1918 pandemic - or that whatever they have chosen to use as the low end for their planning scenerios is automatically to be defined and responded to as as 'mild'- or that the worst we can really expect is the best case scenerio. As your figures show, none of these assertions are true.  (The same can be said for defining their upper end scenerio as 'severe' or 'worst case' for that matter.)

Your scenerio is based on what would be classified as a CAT 2 Pandemic.

A pandemic could be twice as bad as your example and would still only be a CAT 3 Pandemic.

This is the other rub - that in weighing the direct and indirect societal cost of NPI, the impacts of these CAT 2 and CAT 3 Pandemics are judged to not outweigh the damage/cost of the more aggressive NPI - which would still be in the 'consider' or voluntary status for local governments.

While that may be true as things stand today, it leaves behind the closed door the disucssion of what we could do as a society to mitigate those societal costs of NPI (and thus change the balance on that equation) by investing in community resilience measures now.

I agree there is a problem here, but I am not sure you are defining it right when you say there is no such thing as a mild (unmitigated) pandemic. 

It seems to me the more important point is that planning for those mild pandemics is barely worth the cost/effort;  while the need for planning and preparing for the real deal (CAT 2 - CAT 5 and beyond) is something that can get obscured by underestimating the impacts that would flow from even a CAT 2 Pandemic.

*

Category 1, CFR of less than 0.1%
Category 2, CFR 0.1% to 0.5%
Category 3, CFR 0.5% to 1%
Category 4, CFR 1% to 2%
Category 5, CFR 2% or higher

http://www.cidrap.um...

ITW(Joel J)
Courage is resistance to fear, mastery of fear - not absence of fear.
- Mark Twain
 


not sure ...
I think 1957 was depicted as Cat3 in those charts, but I'm not sure about that.  In any case, having 1918 and 1968 as "extremes observed so far" is enough to make the point of "not all pandemics are created equal".  Having all 3 in the same chart - and as DemFromCT has done, even a hypothetical H5N1-like one, really sets the CFR*CAR scenario-space all in one picture.  Which is useful because we're not making predictions, but setting the stage for some discussion.

We have SARS as a (posibly very biased) example of something that happened recently.  CFR near 10%.  Compared to flu, a very low CAR.  Those of us who enjoy this kind of pain could try and fit SARS into the picture as well, but just as a "*", a very small reference, just so that we can comment on it if we have time.

Now, some things are not in the picture at all:

- I think globalisation (just-in-time, many steps from tree to table, almost no stocks), urbanisation and systemic interdependency have all "worsened" (i.e., grown more intense, which in my view is bad) in the past 15-20 years.  I would say it's a lot, but maybe I'm plain wrong.  In my view, this would mean the threshold for "mild" has lowered; i.e., the CFR would have to be lower if we want to call it "low impact".  In short, I think it's less (and less) likely that we'll get a low impact pandemic.  Such a "very low CFR pandemic" is really a big IF.
- What we'll perceive in the first weeks will be an initial, biased and debated CFR.  At least initially, some will think "they die so much because they are poor and not well fed".  Deeper into the first wave, many will remember 1918 was not-so-severe in the first wave.  (Where in the chart would 1918-first-wave fit in?)  So even a low-CFR first wave would make quite a number of people believe that a harder blow might be in the making.  Yes, vaccines would be on their way, too - for the first-wave strain, which would give some protection, yes.  The world would brace for a harder wave and we'd see simultaneous stock-up, i.e., disruption.
- Even with a really low CFR, a high CAR alone might do the trick, and length of disease too.  People don't have to die in huge numbers for us to want to close schools, I think.  It's enough when they are ill enough, and in numbers large enough, to overwhelm hospitals.

So I would say disruption, in un-knowable levels, will affect a very large percentage of the world's population.  If high enough, it will affect 100% of the world's population in a big way.  And it's easy that it will be high enough.

I don't know how I'd rephrase it in a shorter way.  Yet. :-)

You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.


[ Parent ]
you need to read the context
of what I am writing about.  Which is what is the impact of a pandemic that sits at the lowest end of the UK government's planning scenario, for this day and age, in the real world of someone living in a city like London.

From top diary:

I'm going to take the lowest end of the figures used in the UK pandemic plans, 25% AR occurring over the first wave and 0.4% CFR, and see what this means for a city like London.

That is, I did not write it as a scholarly work for the purpose of seeking a definition for the word 'mild', which appears to be the gist of your argument.  Rather, I'm using the word 'mild' in an experiential form to explore the reality of what we are planning for in the UK.  eg is 0.4% CFR really a mild pandemic?

Just as the US government says that 1918 is not the worst case scenario, but we use it for planning purposes, ie the fact that they are using the 1918 scenario does not imply that is the worst that can happen.  Remember the big fights over that one? 

Similarly, my purpose here is to point out that we should not look at the lowest end of the figures used for planning purposes and automatically assume that represents a mild pandemic.

And, if I may add, the system of categorizing pandemics that you describe, while useful, is NOT being used in the UK.  Unless and until it is, for me at least, comparing that in the context of what I'm writing about would not add much other than taking the subject off course.

With all respect.



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
Title and final statement may have made me miss that context ;^)
The gist of my post was this:

Following up on lugon's statement, you asked. I answered.

I think there still are (could be) mild pandemics. 

Saying there are not or could not be mild pandemics is much like saying there can never be anything as bad as or worse than 1918.

And up to a certain point, I think we are better able to handle those mild pandemics today (at least in the developed countries) than we were 90, 50 or 40 years ago.  While the hospital beds are still open, the miracle drugs still flowing, the health care workers still up and around in full force and JIT ariving JIT, a 1957 level pandemic would be a lot less damaging today than it was back then.

But at some severity level there is probably a tipping point and as both you and lugon's post suggest, given our interconnectedness and interdependencies the impact of even lower level scenerios used for planning could result in higher level impacts - and these scenerios should not then be described or planned for as 'mild'.

The UK scenerio you describe is not mild.  We agree.

I incorporated the PSI because it serves as the trigger points for the OSHA NPI guidance that has been discussed here at great length.  I apologize if that seemed to take things off course, but the point I was making needed that reference - that the planners in this country seem to a certain extent to be treating even CAT 2 and 3 pandemics as 'mild'. 

Sorry if my post was confusing on that.

ITW(Joel J)
Courage is resistance to fear, mastery of fear - not absence of fear.
- Mark Twain
 


[ Parent ]
I think you and I
agree more than disagree ;-)

One of the biggest problems driving complacency is failure to understand what those numbers mean.  It won't be easy to carry the message across, but we'll just have to keep working on it, I guess.



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
devil's advocate
Ok, I'm curious, so I'll play devil's advocate.  Couldn't there be a flu bug that is novel, spreads fast and furiously, but only makes people mildly ill?  I doubt that H5N1 will ever be "mild" but it seems to reason that some other influenza could be. 

Pixie, way to go!  I have many battle scars from battling the educational system.  Yes, my district has a requirement to have 180 days of class a year, but I'd be willing to bet that if there was a deadly pandemic or other major crisis, very quickly we would have lessons posted on-line and any day that your kid checked in and did some on-line homework would "count" as a "day" of school. 

The same system that can be mindnumbingly recalcitrant can be surprisingly nimble when teachers, parents, and administrators are on the same page. 


Mild reactions
Olymom,

  There is - a dead virus used to vaccinate.

  I doubt there will be a mild version. Just like there is not such thing as a read car that is blue in color there may not be a mild H5N1. That which makes H5N1 what it is makes it dangerous - as far as I know.

  I hope for a mild version of H5N1.

  Actually I hope those who get H5N1 early, recover and keep things going for the rest of us.

  Yes I believe there will be some part of the population that will fair better than others given the same virus.

Kobie


[ Parent ]
there won't be a mild H5N1
The genetic difference between H5N1 and current human seasonal flu is too big.  Even if a pandemic virus arises by reassortment between H5N1 and a human virus, there is likely to be a big jump in severity from seasonal flu to the new strain. 

The reason why I say that, and this is speculative, is if you look at what happened in Hong Kong in 1997, that H5N1 virus had internal genes from an avian H9N2 virus, which does cause human disease from time to time.  But H9N2 in humans is usually a mild disease, and there is some data from southern China of a low (of the order of around 2-5%, I believe, I can't find the reference now, its quoted from Chinese journals) rate of seroprevalence there.

So if a virus like H9N2 which normally causes mild disease reassorts with H5N1 to produce the 1997 H5N1 in Hong Kong, and killed 6 out of 18 people, do not expect any reassortant with H5N1 to be mild!

That is, as I said, my speculation.



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
Reson to think
SusanC,

  Thank you for the scientific explanation.

Kobie


[ Parent ]
Olymom...look at 1957 and 1968
I believe that those two pandemics were exceedingly mild, compared to 1918 and previous flu pandemics...I actually had the 1968 Hong Kong flu---it hit me on Christmas Day that year. Except for making me very ill, it didn't affect me very much. Ask DemfromCT. No!! Wait!! He's met me...don't ask him!!!  :-)

[ Parent ]
I almost died
in that "mild" pandemic in 1957.  I was only six years old, but I remember very clearly being in the hospital for more than a week, with seemingly constant injections of what I believe now must have been penicillin. 

When you're the one who is sick, even a "mild" pandemic doesn't seem very mild at all. 


[ Parent ]
it depends on what is the context of your discussion ;-)
If you are talking pure science, yes, you could have let's say the current circulating seasonal H1N1 pick up a new HA from an avian H1 which is related but not the same, so the antigenic change is much smaller and the internal genes are identical. 

That's only theoretical, because we don't know whether a single gene replacement will confer significant competitive advantage to the new strain to cause it to dominate (which is needed for it to become a pandemic strain) without replacing part of the polymerase such as the PB1 which was replaced in 1957 and 68.  But if the polymerase is replaced as well, avian polymerases when they first enter humans are much more pathogenic than the human adapted polymerase, so the disease is going to be more severe.  How severe is a matter of degree.

However, in the context of public communication and pandemic policy setting, to the extent that the government is using 0.4% CFR as the lower end of the range for planning, I would suggest that all planning needs to be based on the assumption that there is no such thing as a mild pandemic!



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
it's the same as when you prepare for a hurricane
The reason why people prepare for hurricanes is not because they are hurricanes but because they are worried about a severe or at least a moderately severe hurricane.  Doesn't mean that mild ones don't exist, it only means they don't enter into the equation in the context of preparation!



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
Virulence and transmissibility
This might be a good place for some virology discussion. 

Calling gs ;-) who said there's not enough virology these days!

For influenza viruses, the degree of viral replication directly contributes to its virulence, ie efficient replication is correlated with severe disease. 

If you have 2 different viruses in the same host eg seasonal virus and pandemic virus, they will compete against each other, and the one that replicates more efficiently will win.

Now when we talk about a virus acquiring the ability to go efficient h2h, it's not a ON/OFF, thing, but more of a gradual transition with R0 building up so that it eventually becomes > 1.  As it goes repeatedly h2h, it adapts and the R0 increases.

So a newly arisen ie pandemic virus will have lower transmissibility at the beginning compared to the circulating seasonal virus, but 2 factors favor its survival.  One is the replication that I just mentioned, the other, which is related, is that the host immune system will be stimulated by both viruses but more by the rapidly replicating one ie the pandemic strain.  However, the immune reaction will be much more efficient against the seasonal virus due to the specificity in immune responses.

So even though initially the newly emergent pandemic virus is transmitted less efficiently than the circulating seasonal strain, it wins the battle hands down in every single host in invades.  The more generation of human hosts it goes through, the more it adapts to become more transmissible, until it becomes the dominant strain.

At the same time, the new avian polymerase complex, although very pathogenic to humans, is initially not very efficient.  But it adapts fairly quickly, especially the PB1, so that it's efficiency ie at causing severe disease increases. 

Therefore, it is likely that at the very beginning of a pandemic, the virus becomes more transmissible at the same time as it becomes more virulent.

After the virus has been circulating in humans for some time, the drive to escape host immune reaction against the polymerase causes it to become weaker, hence over the ensuing years or seasons, the pandemic virus attenuates to the 'mild' disease that we call seasonal flu.



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


does it become milder mid-wave?
Because then that would be yet another reason to slow down (NPI) each wave.  Starting from the very first mini-wave in the world (?).

I.e., if the CAR for a given wave is going to be, say, 15% of the population, we can see it running like mad in 30 days (10 generations) or slow it down to say 60 days (20 generations).  If it gradually gets milder within the wave (which I don't know and that's why I ask), then it's safer to catch it on generation 12 than in generation 6.  The community that slows it down will also have a higher proportion of milder cases.

The logic looks sound (please have a go at it too), but I don't know if the assumption is true.  Is it?

You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.


[ Parent ]
I don't think it is easy to predict
to that level of precision.  And it's likely to vary from one location to another, I think.

The bottomline is, I don't think you can bet on when is the safest time to catch it.



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
to put it the other way round, could it be that it's worse to catch it in the second half of a given wave?


You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.

[ Parent ]
I can't say, I haven't read anything about that n/t




All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
if you look at the PB1 gene
from the paper discussed here  showing the evolution of individual genes over time, it will give you a sense of the timescale.  The PB1 gene is shown here

The red crosses are human samples, except for the purple asterisks which are all from H1N1.  The 0 horizontal line denotes the boundary between human-adapted and avian-adapted characteristics - above is human, below is avian. (Go to link above for more explanation.)

The PB1 from 1918 H1N1 became more and more human-adapted until the 1950's at which point it disappeared, due to the emergence of the new H2N2 in the 1957 pandemic.  It appeared again in 1977 due to escape from a laboratory sample.  After that it continued with a very slow rate of change, but the trend is still apparent.

There is only 1 sample from around 1957 (red cross) and you can see it is avian.  The next sample is from around 1968, and from then on you can see how it becomes progressively more human-adapted again.

Another interesting thing to note is that the current circulating seasonal H1N1 (represented by the purple asterisks) causes milder disease than H3N2 (red crosses).  This may be because, as shown by this chart, the PB1 in H3N2 is less human-adapted than H1N1.

So when I say the polymerase adapts initially to become more efficient, I'm talking about a very short timescale, probably in the order of months after it got into humans, until the full efficiency or power of the avian PB1 is fully unleashed.  Which in the case of 1918 might (this is speculative!) explain the early milder wave.  In other pandemics, if this happened very quickly, possibly because they were reassortants with the rest of the virus being already human adapted, the full force of the PB1 may be unleashed within a very short time, then you may not see an early mild wave at all.

In the case of H5, the main adaptation I believe if it ever gets efficient h2h, is likely to be in transmission and not replication ie PB1.  That's why if it goes efficient h2h I would expect the first wave to be the most severe, which is also what Webster thinks.  Other scientists are not speculating on this, at least not in public!



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
sidescroll alert :-)


You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.

[ Parent ]
not for me
I have to go now, I might re-post a smaller version of that slide later ;-)



All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


[ Parent ]
don't worry (not that you would) and thanks! :-)


You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.

[ Parent ]
bump for new readers n/t




All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


1968 was mild
much milder than 1918

ask experts for their subjective
panflu death expectation values
and report the replies


but was it a pandemic?
I'm just kidding.  1968 was a pandemic.

And this situation is a flu pandemic too.

You arm yourself to the teeth just in case.  You don't leave the gun near the baby's hand.


[ Parent ]
The build up
Most people today have become accustomed to things happening quickly.  The pandemic occurring right now (and it is a pandemic, no matter what WHO calls it) is not happening quickly.  The news of increased serious cases and deaths is going to wear at people.  At first sloooowly, just like right now, but persistently.  You can bet these cases will make the news.  And as it builds up steam, rising towards a peak, there will be a corresponding unease build up in the population's psyche.  Finally, during the two or three weeks of peak infection this build up is going to develop into consequences.  Modern society has not had to deal with this before, especially a widespread national event of this magnitude.  The disease may turn out to be "mild" in and of itself for the greater portion of the people who get it, but the effect upon society may not be so mild.  I'm not talking about folks panicking.  I believe folks may just not show up, period.  They will call in sick, whether they are sick or not.  Small businesses may decide it's a good time for a vacation.  In other words, people will hunker down and try to wait the "storm" out.  The prevailing mind set will be "better safe than sorry".  There are consequences to this.  I believe some of the consequences could have a ripple effect all around the world.  Tug one strand of a spider web, and the whole thing shakes.

The U.S. government (and others around the world) need to get in front of this with some straight talk.  Done correctly most everyone will see it as a wise and prudent action.  To not do this, and simply say the pandemic is mild and no worse than seasonal flu,...well, that ain't gonna work.  This is front and center in the news, and will be until it is done.  This is killing young and middle aged adults.  It is not business as usual.  It may be a "mild" pandemic as far as pandemics go, but there is nothing mild about it as far as the day by day, blow by blow media coverage, especially when it takes off within a large population center.

How do you mitigate the potential societal effect?  Not by downplaying the significance.  It is much better to be perceived as being a bit overly protective than as possibly misleading folks for the sake of the economy.  There is a fine line which must be trodden.  Right now is the time.  If you wait until the build up is peaking, no one will listen.  When "better safe than sorry" time has arrived, no one's paying attention anymore.


bump for newbies ;-) n/t




All 'safety concerns' are hypothetical.  If not, they'd be called side effects...


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