Swine flu is killing a different set of folks---young folks

This is not a normal flu season (if you hadn't heard). Normally, summer sees a return of flu cases to a low baseline, but not this year---this year we saw a bump in cases around April, with a consistent trickle of cases throughout the summer, and significant outbreaks at summer camps and military bases. And now, from that "higher low point" we are seeing an early, rapid rise in flu cases. Some of this is likely attributable to an increase in reporting---people are worried and going to the doctor for illnesses that they would normally ignore. But that isn't likely to be the bulk of reported cases.

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Flu visits, from the CDC

An "influenza-like illness" (ILI) is usually defined as a fever of 37.8 or above (100 degrees Farenheit), plus either sore throat or cough, without another explanation, such as strep throat. Many ILIs are not influenza, but during the flu season, the sets of ILI and actual flu increasingly overlap; that is, more ILIs are due to actual flu when there is a lot of flu in the community, making this a useful marker of flu activity. We can't test everyone, so we have to make an educated guess, and the fact that ILI rates are soaring above anything we normally see, combined with samples from surveillance sites, confirms that we are seeing flu rates far above what would normally be expected.

In addition to high rates of flu, the population affected by this flu is significantly shifted to the left, that is, it is affecting (and killing) a younger group of people than the usual flu. While it might not be more virulent than usual flu (with some possible exceptions such as pregnant women), it is infecting an immunologically naive young population who are dying at the rate one sees with flu. This rate is not high, but if enough people are infected, the absolute numbers become rather sobering.

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Pediatric flu deaths, from the CDC

Normally, influenza knocks off the old and infirm, largely sparing the young and healthy. This year, because so many additional people are becoming ill, more are dying. Influenza has a certain mortality rate associated with it, so if flu infections go up, mortality goes up, and if more young people are infected, more young people die.

I'm repeating myself a bit here because it's easy to get this wrong, as many newspapers and alternative medicine websites often do. This flu is a big deal, not because you're going to die when you catch it, but because you're very likely to catch it, and some who catch it die.

This is a public health fact---if enough become seriously ill, we will have to ration care, making decisions about who is allowed to use up ICU and ventilator resources, and who is not. Another public health fact is that this is a preventable illness. We will never vaccinate enough people to achieve herd immunity, but we can vaccinate enough to blunt the infection rate and the mortality rate. Vaccine supply and distribution is a problem, but if you keep an eye on your local public health department, you will likely find a vaccination clinic and time near you. Vaccinations are being given using a triage system to get the highest risk individuals and health care workers first.

I've heard a bit of moaning about health care workers being at the head of the line, but there's a good reason for this. First, we don't want health care workers getting the flu and spreading it around. Second, we need healthy doctors and nurses to stay at work and take care of the huge increase in sick people. We must be able to staff all of our beds, and still be able to send people home when they have the flu.

This pandemic is serious business. It's easy to think of it as being over-hyped---that makes all of us feel more comfortable about it. And the hype can be overblown. That's why it's important to understand the facts. Let me personalize it for you: I have a young, asthmatic daughter. She is the single most important fact in my life. When I read the anti-vaccination propaganda about "saving your child", I feel it---I feel the tug of balancing risks. After all, she's not sick now so why risk anything that might hurt her?

But I read the facts and I educate myself. I know that the risk of becoming ill or dying from the flu is many times higher than any problem from the vaccine (some might say the risk is nearly infinitely different), and I know that the vaccine is her best chance to avoid the flu.

And I remember laying in a hospital bed with her while she struggled to breathe, holding a little oxygen mask over her face because she was too young to leave it on herself. I remember how frightening a lower respiratory tract infection can be in a vulnerable person. I see how busy the ERs, clinics, and wards are and wonder, if this gets bad, will there be room? Will there be an oxygen line for my daughter, my heart?

That's why my family takes this seriously and is going to get vaccinated.

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I've been thinking about how the recent increase in children's deaths from the flu contrasts the usual cry of the anti-vaccinationists about how vaccines *hurt* kids. While we usually meet these charges with research data and reason, which are countered with derision,I thought instead, we should try personal stories from the elderly about epidemics of the past.Some commenters have provided them; or you can walk through any 19th century cemetary and see the ages of many of the dead(e.g. Greenwood in Brooklyn, NY).Pal has provided a picture of those who are currently at risk: young children, especially those with conditions like asthma.Last night, I somehow wound up in Greenwich Village where the annual "parade"(more like a rave really) was happening:I suddenly realized that most of the thousands there mardi-gras-dizing 6th Avenue were in the high risk age group(under 24). If data and reason don't work maybe emotions,stories, and photos are needed.

By Denice Walter (not verified) on 01 Nov 2009 #permalink

Ran into my former OB partner Saturday. He said one of the other docs, an internist, had a 21 yo previously healthy man come into the ER this week and died within 4 hrs of admission of H1N1. Scary!

Pal,

I have been wondering about something, people with asthma and pregnant women are supposedly being more strongly affected by H1N1 than by seasonal flu.

I have wondered what the connection could be, and came up with one hypothesis. Somebody else suggested another. I wondered what you think.

There has been a claim that asthma may be caused, in part, by the failure of the adaptive immune system to develop properly due to lack of exposure to enough antigens to train it. This means that the innate immune system over-reacts to ordinary exposure. The adaptive immune system is also repressed in pregnant women.

Could it be that the weak response of the adaptive immune system, along with an over-reaction by the innate system, is responsible for high mortality?

The alternative hypothesis is that both asthmatics and pregnant women breathe more shallowly than others. The H1N1 flu penetrates more deeply into the lungs than seasonal flu, so these populations are more susceptible.

Could there be something to either of these ideas?

It's sort of an adaptation of the "hygiene hypothesis", but none of this is really known. An alternative plausible hypothesis is that asthmatics (who are affected by seasonal flu badly as well) have bad airways...they are prone to bronchospasm and have preexisting inflammation/caliber of airways, and react to the insult of infection similarly but since the airway is already somewhat compromised, don't do as well.

Pregnant women have immune systems that behave differently in a number of ways.

I understand why they prioritize certain groups, particularly healthcare workers... BUT...

Med school campus won't give me vaccine because I'm not a med student (technically because I'm not involved in patient care).
Undergrad campus won't give me vaccine because I'm 25 (cause the virus is gonna check my birthdate that accurately??).
Pa department of health does not want to give any info online on how to get the vaccine (there is a link for clinic info, but no clinic info).
Nobody will give baby vaccine because he's only 2 months. He has sniffles and is coughing (though no fever) and I get no sleep when he gets fussy from sickly.

*glares at world*

@BaldApe- in a general sense, you may be on to something. There are many illnesses that are at their most deadly when the innate immune system goes crazy (the phrase to look for is "cytokine storm"). Malaria is one of them, and nasty influenzas (e.g. 1918 pandemic) are thought to work that way too.
I generally think of the hyperinflammatory side of the innate immune system, but a role of the innate immune system is to inform the adaptive immune system (to tailor the response). So there are lots of checks and balances built in, and the innate immune system can provide anti-inflammatory signals as well as pro-inflammatory signals. It's almost certain that asthmatics and pregnant women have different patterns of cytokine responses than a 'regular' person would, but I don't know if the total cytokine levels skyrocketed in either, but it'd be interesting to look at.
It's also possible that problematic innate immune responses to influenza aren't due to cytokine intensity per se, but that the damaging cytokines stick around too long (because normally the adaptive immune side is supposed to kick in and help turn them off). This could also be different in different populations.

becca: You have my deepest sympathy. The only thing worse than a sick baby keeping you up all night is a baby who is no longer keeping you up all night because s/he is in the hospital. I hope your little one feels better soon!

I've read that most of the deaths from H1N1 during pregnancy have occured when the woman becomes sick during the third trimester. If this is accurate, it suggests a possible mechanical problem, i.e. the lungs expand properly to allow good air movement leading to atelectasis and increased vulnerability to secondary pneumonias, ICU stays, and death. But since I don't even remember my source and I'm sure it's not from the primary literature, I don't want to promote this hypothesis (guess) too strongly.

Our school was supposed to have H1N1 vaccines for students. The county canceled. I guess they got less than 15% of the vaccine they ordered. Our ped doesn't have it. The county health office is scheduling appointments for January at the earliest.

I couldn't even read the post, sorry. Too scary.

By micheleinmichigan (not verified) on 02 Nov 2009 #permalink

Some commenters have provided them; or you can walk through any 19th century cemetary and see the ages of many of the dead(e.g. Greenwood in Brooklyn, NY)

We recently took a stroll through the Catholic cemetary in Quemado, NM -- and took pictures of the old headstones. Bear in mind that this is about as pure air as there is, strictly organic free-range cattle, chickens, and children, etc. No industry, no mining. Just agriculture since Territorial days.

And there were whole groups of kids who died within weeks of each other. There were whole families (mothers and children) buried together who died within days. A remarkable number were from the autumn of 1918.

For the "any excuse will do" set, bear in mind that this is a small rural town in New Mexico. I suppose it's possible, but I seriously doubt that there was a doctor in town then (there sure isn't now) so the "iatrogenic death" excuse doesn't work either.

By D. C. Sessions (not verified) on 02 Nov 2009 #permalink

D.C.@9: Those who refuse to learn from history are condemned to repeat it.

becca:

I understand why they prioritize certain groups, particularly healthcare workers... BUT...

Med school campus won't give me vaccine because I'm not a med student (technically because I'm not involved in patient care).
Undergrad campus won't give me vaccine because I'm 25 (cause the virus is gonna check my birthdate that accurately??).

In the ironic category, we had a very healthy, active adult die of 2009 H1N1 here in Minnesota. He was a hospital administrator, and thus eligible for the H1N1 vaccine -- but what they were giving out was the nasal version, and he was one year too old to qualify for that. The injected variety hadn't arrived yet. Of course, he died early enough that even if he had gotten the vaccine, he might not have had immunity yet anyway. But it adds to the poignancy of the story.

By Calli Arcale (not verified) on 02 Nov 2009 #permalink

This pandemic is making me insane. I have three kids, one of whom is medically fragile for a number of reasons, but particularly scary in light of H1N1 is that any time he gets a virus and is sick, his gastroparesis flares up to the point that sometimes he can't even absorb clear liquids through his GI tract. At all. Which is, you know, BAD. My pediatrician only got twenty doses of vaccine but used three on my kids to create "household herd immunity." I qualified for a dose through the Health Dept. as the primary caregiver of a disabled person. Which is good since I also have asthma. Over the weekend I spent three hours standing in line with a friend who has two donor organs so that he could get the shot, too, and I just found out my kids need a SECOND dose. Lately my life revolves around getting loved ones vaccinated for this thing. I wish it would go away because on top of the death tolls and widespread panic it is making me VERY cranky!

Hmm...time to lay a bloggy beat-down on another quack.

I am looking forward to a "beat-down". I would like to see how you will dispute the facts from the very organizations that you claim are legitimate.

Beat-down accomplished.

For future reference, djay, anything with "Mercola" in the link? Not so useful, dahlink. Do feel free to try again next week.

By LanceR, JSG (not verified) on 03 Nov 2009 #permalink

So, djay, any chance that you saw the beat-down and actually understood it? You haven't really posted much on that post.

djay: You have just brought a pair of embroidery scissors to a gunfight.