Swine Flu – Science, Pseudoscience, And Panic
In 1918 the Spanish Flu (named after the country of origin of the first identified case) swept the globe, killing 20-40 million people – more than the First World War (which killed 15 million) which was just ending. When an epidemic spreads to multiple regions, especially multiple countries or continents, it becomes a pandemic. Flu pandemics happen every 40 years or so, and we are due for one now.
This is probably partly why there has been so much news attention, even some mild hysteria, surrounding recent outbreaks of swine flu, beginning in Mexico. It is hard to say how many cases and how many deaths there have been so far, because information from Mexico is spotty. Specifically it is difficult to say if people who have died with flu-like symptoms really had the swine flu or something else. Estimates are that about 150 people have died in Mexico with the swine flu. It is clear that we are dealing with a new strain.
Some Background on Influenza
But first, a little background. The influenza or flu virus is an RNA virus that comes in three genera – A, B, and C. Influenza A is the most common type. It can infect mammals and birds, with aquatic birds being its natural endemic host. Each year there is a seasonal epidemic of Influenza A, infecting millions of people and killing 100-200,000 – mostly the very old, the very young, and the sick.
Influenza B is less common than A and infects only humans, seals and ferrets. Influenza B mutates slower than A, and so has less genetic diversity and is less virulent as a result. Influenza C infects humans, dogs, and pigs and is the least common type, but can be virulent when outbreaks occur.
All off the pandemics over the last century have been of Influenza A. Its primary weapon is its ability to rapidly mutate, avoiding the immune systems of its hosts. This is why each year new strains of Influenza A are causing that season’s epidemic.
The flu starts out like a common cold, but lasts longer and becomes more severe. It is characerized by high fevers, muscle aches, fatigue, headache, and severe cough.
Influenza A strains are designated by the two main proteins that determine their infectivity and virulencs -haemaglutanin and neuraminidase, H and N. There are 16 Hs but only H 1-3 infect humans, and there are 9 Ns but only 1 and 2 infect humans. Haemaglutanin is a protein that allows the virus to latch onto and infect host cells, while neuraminidase allows expelled viruses to reinfect other cells.
The swine flu virus is Influenza A H1N1. This strain came about probably by four different strains of Influenza A infecting the same host (probably a pig, hence the name swine flu). Viruses can exchange genetic material, so one strain can combine bits from other strains, creating a new strain. The current swine flu likely combined bits from a human virus, a bird virus, and two swine viruses, although this is still being confirmed.
The flu is potentially a fatal illness, killing about 1% of those infected. Death results from one of three types of causes – the flu infection itself can cause a serious pneumonia (lung infection) that can impair breathing to the point of death. A serious infection can also leave someone open to a superinfection (another organism causing a second infection while the host’s immune system is occupied with the flu). And those who have a chronic underlying illness may succumb from the added physiological stress added by the flu.
Should We Worry
This week on the SGU we interviewed Mark Crislip, and infectious disease doctor, host of Quackcast, and contributor to Science-Based Medicine. We discussed in detail the latest swine flu outbreak, and what level of concern is currently appropriate. The bottom line is this – this is a new strain of flu virus which appears to be spreading. It has the capability of producing a world-wide pandemic, and if it does it could theoretically rise to the level of the 1918 pandemic which killed millions. Some of the reported deaths from Mexico were young healthy adults (which was also common in the 1918 pandemic), which can mean that the strain is virulent.
But it is too early to tell. This epidemic may also fizzle out quickly, ultimately affecting very few. In 1976 there was a swine flu epidemic with concerns that it would be the next big pandemic, but it just fizzled and amounted to nothing.
What determines whether this latest strain with be a bang or a bust is how infectious it is (how many people will catch the virus) and how virulent it is (how may infected people will die from the infection). We do not yet know how this current swine flu will behave – we don’t have enough data points yet. Probably we will not know until the pandemic is underway, or until after it has burnt itself out.
At this point in time there is no reason to panic or make major changes in your lifestyle. The World Health Organization (WHO) and the Centers for Disease Control (CDC) are watching closely and will make recommendations. As of May 3rd the CDC reports 226 laboratory confirmed cases of H1N1 flu and 1 death. At present the CDC recommends the following:
People who are sick are urged to stay home from work or school and to avoid contact with others, except to seek medical care. This action can avoid spreading illness further.
That’s it – they are not recommending that we limit international travel or that we start shutting down schools. Essentially, if you have a cold or flu-like illness, don’t tough it out and go to work – stay home and seek medical care if necessary.
The WHO has similar recommendations. They are not recommending limiting travel at this time.
Very informative story.Now if the media would only start telling the facts instead of drumming up a panic.
The US CDC is not recommending closing schools and public places. In Mexico, they had a 5 day shut down of almost everything.
Was that because they were over-reacting or because of the different infection rates?
that was because mexican goverment unknowed the kind of virus and the way to infected people primarly,, so Mexico take suddenly actions like level 5 before level 4 and this was great and helps too much the mexicans..
It’s nice to here the ‘real’ recommendations, because the local news keeps saying people should cancel their trips to Mexico. There is also a trend of people with absolutely no symptoms checking into the local medical center demanding to be tested for swine flu (I live in western Missouri, there has only been one person in the entire state who has it, and they live in a completely different county).
And it looks like they’ve finally begun to call it by its proper name of H1N1 thank goodness.The way the nations of the world have been concocting so many different names for it:swine flu,mexican flu,and “The novel virus”,to name a few,has been confusing and unnecessary to say the least.I lol’d especially hard at Israel’s changing of the name to avoid mentioning pigs.
Call it what you want, but it will be remembered as the 2009 Mexican Flu, just like the 1918 Spanish Flu, 1957 Asian Flu, and 1968 Hong Kong flu.
Quote:
“Each year there is a seasonal epidemic of Influenza A, infecting millions of people and killing 100-200,000 – mostly the very old, the very young, and the sick.”
Um, Okay. Is that for the US, Canada, North America, the UK, northern hemisphere, southern hemisphere, the world? Stats without stats are pretty meaningless.
C’mon folks, especially you intellects who write the blog, please remember, the web is global, and, I know it’s hard get this down, but the US is not the world.
Those stats are for the world and your ‘US-centric’ jibe is a cheap shot. You won’t find evidence of that here. The blog supports the effort to get a pilot program onto American TV. Plus, the world is not the US.
I believe the number for US annual flu deaths is ~36,000, but I can’t find the reference at the moment.
There was something in science news a few months ago that said the National Institute of Allergy and Infectious Diseases (NIAID) has claimed that many deaths due to the 1918 Influenza pandemic were actually caused by secondary infections of bacterial pneumonia for which we now have antibiotics to prevent/cure, implying that even without a vaccine we have some tools to prevent many more deaths compared to 1918 even if there is a more serious global pandemic.
According to the National Institutes of Health:
http://www.nih.gov/news/health/aug2008/niaid-19.htm : “the availability of antibiotics during the other influenza pandemics of the 20th century, specifically those of 1957 and 1968, was probably a key factor in the lower number of worldwide deaths during those outbreaks.”
It’s also worth pointing out that, while we don’t (yet) have a vaccine against this current strain, we do have antiviral medications (tamiflu, etc) to treat you if you do catch it. Not to mention the years of planning and preparation the public health community has put in, particularly since the SARS scare, to deal with The Next Pandemic. So even if H1N1 turned out to be as deadly as the 1918 Influenza, we still wouldn’t get anything approaching those kind of death rates.
You should watch this TED Talk before you rest assured that anti-biotics and Tamiflu are going to save us:
Laurie Garrett: What can we learn from the 1918 flu pandemic?
“Those stats are for the world….”
Ah, good. Thanks.
“… your ‘US-centric’ jibe is a cheap shot. You won’t find evidence of that here.”
Indeed you will. And if you review the last several months’ posts you will see that I am not the first, nor the second, person to post such a comment.
“The blog supports the effort to get a pilot program onto American TV.”
Huh?
“Plus, the world is not the US.”
No! Tell me it ain’t so. :)
I’m glad to see someone being rational about this. Already, schools in my area have started a policy of closing completely if a student or teacher gets swine flu, and my canceled most work-related travel to Mexico (not that there was much to begin with). Yet no one would consider closing a school for two weeks when students get the more common strains of flu, which happens every year.
I wish that people would care as much about the typical flu as they do about the swine flu. I hate it when people come into work when they have “just the flu” and spread it around. And people should be washing their hands regularly, epidemic or not.
If you check the ratings for Cable TV news shows, you’ll see they spike dramatically during times of real or presumed ‘emergencies’. They have a vested interest in amping up viewer panic and some of them certainly – and cynically – do just that. Shades of the boy who cried wolf, but crying wolf in the TV news pays.
Good point, that’s why whenever they start this kind of ‘scare’ coverage about something I just turn it off. If everyone else did the same, their plan would backfire on them , and maybe they would learn to moderate their coverage…. I know, I’m just dreaming, but I’m just an optimist.
I don’t understand why you say we’re “due for one now.” That statement seems to be no better than the unreasonable panic that news programs are spreading. I will assume you meant that 40 years is up since the last one, so those who blindly follow meaningless patterns will expect a pandemic.
CNN reports comments made by a 94 year old woman who somehow remembers the 1918 pandemic flu. That was 91 years ago! How the hell does this woman remember it? Does anyone remember anything that happened at age 3? I sure don’t, and I’m in my 40s. Hard to imagine remembering anything at any age at 94, let alone that fact that it happened to her at age 3!! I don’t buy it.
She was probably just remembering the stories that people told about it when she was young. She now has incorporated those memories as though they had actually happened to her. That is a common thing that almost everyone does, but we don’t realize it until the evidence proves us wrong.
Well, my grandfather was sharp as a tack at 101. And on the other end of things, my wife has some very vivid memories from when she was 3. So it’s not impossible… but I share your skepticism.
Different people remember their extreme youth differently, for instance I recall teaching myself to read at 3 years of age, and the fact that my father didn’t believe it… so he’d have me read Billboards (much more common in the 1950’s than today) as we drove by. Probably also why I read 600 wpm instead of the usual about 300 wpm.
J/P=?
I can’t remember what I had for lunch yesterday.
This shouldn’t be reason to worry right now. The flu is the flu (as far as the layperson is concerned). There are many helpful health resources available that provide help and tips on how to prevent the outbreak of the flu. It would help us all.
I’ve heard the terms of A, B, and C before but never knew what they meant. I’m curious to look into it more now. Humans, seals and ferrets seem like an odd bunch (well, odder than the rest) to have some particular thing in common to be affected by Influenza B.
That’s not entirely accurate: CDC is advising: “Dismissal of students in a school and closure of childcare facilities should be considered in schools with one or more laboratory-confirmed or non-subtypable influenza A case among students, faculty or staff in order to decrease the spread of illness in the community.” http://www.cdc.gov/h1n1flu/K12_dismissal.htm
Emphasis mine.
If the media covered seasonal flu as closely as they cover swine flu — tracking its spread, tallying tens of thousands of deaths — it would look just as alarming.
Some statistics won’t tell you whether the flu is seasonal or pandemic. For instance, the mortality rate of hospitalized patients is around 15% in both cases. If they’re hospitalized, they have complications either way.
But the hospitalization rate (and thus the mortality rate) can be 10 times bigger in a pandemic, and as was mentioned, it kills healthy young adults.
Up to 40% of the population can come down with the flu in a pandemic, but up to 20% can come down with the seasonal flu. Both can be very contagious, but there’s no immunity (or vaccine yet) to swine flu.
The confirmed cases are a tiny fraction of the people who are actually sick. It’s not a random sample, so it’s hard to draw conclusions from it.
Recommendations
If you go to the hospital with just a cold, you might catch the flu at the hospital. Wouldn’t that suck.
A surgical mask filters the air you breathe out. An N95-rated respirator filters the air you breathe in.
When you wash your hands, do it right. Don’t touch the faucet and door handle afterwards. Otherwise, it gives a false sense of security.
There was a recent study that the influenza virus spreads easier when the absolute humidity is low. Humidifiers might help.
Should you be exercising and building a strong immune system if the immune response is what kills people? Don’t know.
I’m still not sure if Vitamin D helps or suppresses the immune system, but here’s an interesting theory.
“Epidemic Influenza And Vitamin D”
http://www.medicalnewstoday.com/articles/51913.php
“A surgical mask filters the air you breathe out”…
I think the purpose of wearing the mask for those who don’t have the virus, is to discourage them from touching their nose and mouth with a possibly contaminated hand. Granted most people think that they are filtering out airborne contamination.Maybe health officials should be more clear on this point.
Dr. Novella -“The flu is potentially a fatal illness, killing about 1% of those infected.”
Come on, seasonal flu isn’t that deadly, it’s more like 0.2%.
The mortality rate from the 1918 flu was around 2%. You mean to tell me it was only twice as deadly as seasonal flu?
“Death results from one of three types of causes – the flu infection itself can cause a serious pneumonia (lung infection) that can impair breathing to the point of death.”
Due to the immune response and inflammation, correct?
The CDC is not recommending closing schools. Well, I live in Dallas, TX and my kids schools was canceled this week. So, all these kids are now out in malls, parks, museums with much more contact and chance of spreading any and all virus’. oh well.. Wish my office would close. We’d go to Disneyland with no crowds.
I was going to keep my nose out of the flu hoopla, until I came across this perhaps inevitable snake-oil scaremongering:
http://enjoyingyourhealth.com/2009/05/02/swine-flu-update-for-bipolar-people/
ok I can’t help but comment. I’m a chemist. so something I noticed about their first product, their “Kangan water”? they say it’s both “alkaline waters” and “super acidic water”. so it’s basic and acidic at the same time, is it? so it’s just plain ol’ water? ok. gotcha. good to know. ;)
@Shane: Yep, I’ve always said that schools are breeding grounds for disease – and now that all the kids have their pet germs and are running rampant with the rest of society that’ll probably increase infection rates. Fortunately the “swine flu” is probably an almost insignificant proportion of infections. I’m amused at how some people seem to forget about all other diseases and hazards and only think “swine flu”.
This reminds me of the “bird flu” scam, except that unlike the “bird flu” this one might actually have some chance of doing damage. Anyone remember the hype around “bird flu”? I was getting hoarse screaming at people that they have to put in an effort to try to get the disease and even then the chances of getting it were minimal – and yet stoopid governments, for example Australia, went out to stock $$$ of TamiFlu(tm) to be administered to politicians in case of an outbreak – seriously, it’s in the news – protect the politicians, screw the rest of the nation. Basically people bought the BS about a mutation into a human-human transmissible form despite the fact that there was absolutely no evidence of human-human transmission and there really is no reason to believe that there is any likelihood of such a mutation. Well, I guess in a cannibal society human-human transmission of bird flu is possible.
One doctor, I forgot who, warned that the next flu pandemic most likely won’t be an expected strain like H5N1 bird flu, but some unexpected strain.
But what a scam, preparing for a catastrophe BEFORE it happens instead of after.
How do you prepare for a catastrophe after it happens?
The swine flu paranoia has spread to my office, especially since one of my coworkers went on a trip to Cancun. There are people, most of whom sit near his desk, who are seriously considering wearing face masks and gloves upon his return. I tried researching and giving them the most up-to-date facts, but so far I’ve met ridicule and anger (at our coworker for his future crime of “bringing swine flu to the office and therefore infecting all of us and therefore infecting our families” – ). In trying to alleviate their worries, I told them that they should know what to do if they experience flu-like symptoms and understand that knowledge of what to do is better than living in fear. I also factor into their reaction the fact that everyone in the office knows our coworker to be kinda a jerk. Any advice for this situation?
@Bob: Yeah, I’d tell the guy who went on that trip to Cancun to cough, sneeze, and sputter and act like he’s dying – the sort of melodramatic act that Bugs Bunny likes to put on. That’s certainly what I’d do if I came back from a trip and everyone treated me badly because of some stupid paranoia. The swine flu is no joke, but hysteria is way up on the stupid scale. Your cow-orker would be silly to miss such an opportunity to make everyone else in the office look lame.
Self-destructive behavior.
Well, my coworker finally returned from his trip to Cancun today. And… nothing happened. No one freaked out, no one even was nervous. I’m just glad that there was time to calm down from the anxiety people were initially having at the idea of having someone come back from Mexico into our office.
Haha, everyone forgot about the swine flu idea when they saw his suntan!
Quick question… you say only H1-3 infect humans; wasn’t last year’s bird flu H5N1? I seem to recall we had human infections (but not human-to-human transmission, if my memory serves me right).
Nice and accurate post. Finally people are calming down.
Granted, the situation is different in Mexico than elsewhere, but I think most of the world is overreacting outside of Mexico.
Instead of whipping up such a global fear, media should have had a dose a skepticism and humor
http://outofsight.tumblr.com/post/103640971/more-from-evolved-and-rat-i-onal-hilarious
Question for doctor Novella;
The largest casualties of the 1918 epidemic was the young adults. Could this be, because that was the age of the majority of travelers at the point in time. Instead of something different in the virus?
max
40 million people died! How many of them do you think were travelers?
There was something different in the virus that caused healthy immune systems to overreact with a cytokine storm.
A lot of them died as a result of their immune overresponse– there lungs catastrophically filled with fluid & immune cells. They literally were fine one minute and dropped dead the next. Another problem is that most of it was contracted and spread by the armies, mostly made up of very young men. The book “The Great Influenza” goes into detail.
RE: Alarmist Media – Pursuant to the fact of media hype propagated to increase viewership, hence, ratings, hence ad revenues, they look for certain features of a story or event – or prospect of a story or event – to identify a given as a potential money-maker:
Randomness – The event must appear random, unpredicatable in its timing, seemingly coming out of nowhere, for this increases fear and fear drives viewers back to the media seeking new info, updates, etc. Far more people are killed by auto accidents, heart disease, or even the ‘regular’ flu, but those are all ongoing, omnipresent, and don’t carry that sense of randomness and unusualness, seemingly coming out of nowhere.
Fatality – There must be potential for death, the more the better, in order to amp up the aforementioned fear and constant returns to the given media for new info, updates, etc.
Official Intercession – It helps make an event more hype-worthy if government and/or professional organizations are studying it, addressing it, commenting on it. Worst case scenarios are promoted by repetition, and even when accompanied by disclaimer, they drive up fear and return viewership. What really helps is if someone in authority speaks out in a way that indicates they are feeling fear and panic as well (think VP Joe Biden on current Influ A H1N1).
History – The needed sense of randomness is not affected by cyclical recurrences. That the 1918 outbreak killed 40 million, and that outbreaks tend to come in multi-decade patterns leaves the random aspect intact. But, that the event has killed in large numbers before serves to amp up fear, and return viewership, ratings, etc.
Types of human-threatening events that meet these criteria would be volcanoes and earthquakes that are ‘due’ to recur any moment (despite that ‘due’ on geological time scales can translate into many,many human generations), meteor strikes to earth surface, serial killers and rapists, and, of course, pandemics of communicable diseases.
The media can rightfully claim a duty to inform, but nonetheless amp up the hype to induce fear, which in turn increases viewershp, ratings, and ad rates. CNN yesterday aired several 5 minute spots asking whether media was overplaying and amping up the H1N1 scare – while wrapped around that were numerous other spots by CNN amping up the H1N1 – in what appeared to be an attempt to provide themselves plausible deniability (“But we played stories on media hype and fear-mongering!”).
We also see the hyping-for-ratings on a smaller scale, where blurbs for a weather report coming after a commercial break go something like this, “Are your kids at risk of lead poisoning? More after this…” where it turns out that, no, your kids aren’t at risk. The lead levels measured in the paint at a local school were far below the safety threshhold. Weather reports routinely predict worst-case scenarios, so viewers will keep tuning in for more info, plus, if they’re right, they’re right, and if they’re wrong, the viewer is merely relieved, not annoyed or angry.
Use RoboSkepticism whenever consuming media reports on just about anything.
Good summary, DA. One observation:
It helps, but it’s not necessary. All too often, the story starts out as “Why isn’t the Government doing something!!” Which is what drives the government agencies to explain what they are doing. Which often just feeds the cycle…
I didn’t say these features were necessary, only that media look for them in hypable stories, but yeah…
This just in from the Contradictory Declarations Commission: the Acting Director of the CDC is quoted in the NY Times this morning saying that “Closing schools is not effective.”
http://www.nytimes.com/2009/05/06/health/06flu.html?_r=1&ref=world
Which is fine, but they need to revise the guidance on their website. (Posted at #13 above.)
http://www.nytimes.com/2009/05/05/health/05well.html?em
“If the flu does progress to a pandemic, the most effective response will be to limit public gatherings. In 1918, for example, the outbreak in St. Louis was mild, because the authorities closed schools, churches and theaters. Meanwhile, Philadelphia, which had one of the highest death rates, held a war bond parade at the start of the outbreak.”
I have the same question as #22/Wilson.
If “only H 1-3 infect humans”, what’s the story behind H5N1 Bird Flu?
H5N1 either had a mutation or got the human-infecting ability through gene exchange with a human-infecting virus. That’s what scientists mean when they talk about a virus “jumping” or “crossing” the species barrier.
Well this is cool: copper inhibits the influenza virus. Bring back the copper doorknobs.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1855605
Influenza A virus particles (2 × 10^6) were inoculated onto copper or stainless steel and incubated at 22°C at 50 to 60% relative humidity… After incubation for 24 hours on stainless steel, 500,000 virus particles were still infectious. After incubation for 6 hours on copper, only 500 particles were active.
Looks like it’s old news.
http://www.nytimes.com/2008/03/26/business/26microbes.html?_r=1&scp=2&sq=copper&st=nyt&oref=slogin
Researchers who worked on the concept expect hospitals and other public institutions to be the initial market for the product, based on the approvals gained by the trade group. The tests showed 99.9 percent kill rates within two hours against the leading antibiotic-resistant bacteria now plaguing hospitals, said Harold T. Michels, senior vice president for technology and technical services at the trade group
Scores of consumer products are already in the market with coatings impregnated with silver and other antimicrobial substances, some of which have been advertised in ways that lead users to believe they reduce infection risks. But the only legal claims those products can make is that they protect the product itself from bacteria, mold or other microbial organisms — for instance, they eliminate odors from the product, prevent stains or slow its decay.
Speaking of media alarmism…. yikes. This early evening here in eastern rural NC, a tornado touched down 3/4 of a mile from our home, pulled back up, went right over our house (I got some video), and headed off to the ENE and presumably out to sea.
Not an alarmist word out of local media! It’s pretty clear now that my earlier post on media hype and fear-mongering for fun and profit has permanently changed how they’ll do business now.
Oh but tornadoes are boring unless they rip up trailer parks and houses; besides, not everyone is threatened by a tornado but many people can be scared by something they can’t even see. If you have some video of a flying pig then that would be something the news might be interested in.
Huh? We have flocks and flocks of avio-porcines in sky-pens all across North Carolina. It’s one of our primary agricultural products.
One flu over the coo-coo sty?
I Emailed this letter to the Atlanta Journal, but of course they didn’t have the nads to print it:
We don’t have to worry about the swine flu down here in the Bible belt. Disease management is based on principles of biology, including genetics and evolution. And we don’t believe in that sort of nonsense around here. Who needs the CDC?? We have God on our side! The only thing we need to do is PRAY. I’ll wait for Gov. Perdue to call me down to the capitol steps.
The first sentence of this article contains a blooper. The name of the Spanish flu does not come from the “the country of origin of the first identified case”.
According to Wikipedia and other sources, ‘the 1918 Flu received its nickname “Spanish Flu” because Spain, a neutral country in WWI, had no special censorship for news against the disease and its consequences. Hence the most reliable news came from Spain, giving the false impression that Spain was the most—if not the only—affected zone’.
In this day and age I expect any skeptic to instinctively do internet searches of the things presented as facts in web articles. Doubly so for authors publishing articles for skeptics.
The fact that nobody noticed it in the comments yet is proof that people let their guard down when reading this site. There is room for improvement, just use the right-click of you mouse.
[citation needed]
http://virus.stanford.edu/uda
“The name of Spanish Flu came from the early affliction and large mortalities in Spain (BMJ,10/19/1918) where it allegedly killed 8 million in May (BMJ, 7/13/1918). However, a first wave of influenza appeared early in the spring of 1918 in Kansas and in military camps throughout the US… There was virtually no response or acknowledgment to the epidemics in March and April in the military camps. It was unfortunate that no steps were taken to prepare for the usual recrudescence of the virulent influenza strain in the winter. The lack of action was later criticized when the epidemic could not be ignored in the winter of 1918 (BMJ, 1918). These first epidemics at training camps were a sign of what was coming in greater magnitude in the fall and winter of 1918 to the entire world.”
Sound familiar?
There is another element of this that cause the over-concern of swine flu and that is that Mexico’s healthcare is really lousy compared to that of the United States. The lethality of the initial reports of the disease were overestimated.
Second, just juxtapose deaths from swine flu and regular flu and you will get an understanding of the difference between frequency and proportion.
Are you suggesting that swine flu is less virulent than regular flu?
Max- What I have read suggests that the virulence may be about the same as seasonal flu so far, but experts say it is still too early to tell. This from the Washington Post May 2nd:
“The early signs from the United States and a few European countries where the strain is spreading suggest it is not unusually dangerous, as there have been few deaths so far. If that continues to be true, then it may help explain the mysteriously high mortality in Mexico. It may be that Mexico already has had hundreds of thousands, and possibly millions, of cases — all but the most serious hidden in the “noise” of background illness in a crowded population.
The fact that most people infected in other countries had recently been to Mexico — or were in direct contact with someone who had been — is indirect evidence that the country may have been experiencing a silent epidemic for months. ”
It does appear to be fairly infectious though.
So far, out of the confirmed cases of swine flu, the hospitalization rate has been 5%, which is 4 to 16 times higher than for seasonal flu.
But as I mentioned before, the confirmed cases are not a random sample, and they may be more severe than typical cases of swine flu.