Is a flu epidemic any more likely now than say 10 years ago?

(This may have been asked but Search won’t let me use “flu” as a term)

I’m mystified why there’s all this hype about flu readiness, as though it’s something just waiting to break any day now. Couldn’t it have broken at any point since the last epidemic? Political cheesy-news hype aside, is there any reason AT ALL to be more worried now about a flu outbreak than we should have been ten years ago?

I’d think the chances of a flu epidemic IS higher than 10 years ago, due to the continuing increase in people without health coverage. Most health plans recognize that the cost of preventative anti-flu shots for everyone is cheaper if it prevents even a few cases that would have needed more expensive treatment. So most health plans make anti-flu shots available free or at a reduced cost.

In the USA, it now about 1/6th of the population that has no health care coverage. And most of them are children, who are at high risk (congregating in schools and day-care centers) and having lower resistance than adults.

I’d also think the continuing trend for more of the population to live in urban vs. rural areas, and to work in businesses with large groups of workers together would slightly increase the chances of flu spreading faster and leading to an epidemic.

Finally, I’d think that prompt and effective action by government officials at the first signs of an epidemic would be critical. Without getting into a GD political debate, I think that recent history (like Hurricane Katrina, etc.) show that the current government officials aren’t very well prepared to do this.

Well we have “flu epidemics” every year. Some worse than others. But the hype is specifically over the H5N1 avian flu (“bird flu”), and the threat of a pandemic involving a truly lethal flu virus a la 1918. And that threat has become very much more probable. This is due the jump the H5N1 virus made beginning in 1997 into the human population. Combined with sudden rapid spread of this this strain among the bird populations from East Asia to Europe.

That jump and the epidemic among the birds are worrisome for a variety of reasons. But one of the main ones involves influenza’s capacity to mutate in a modular way - where two separate influenza viruses can trade “modules” or the genetic information of discrete parts, and you get a blended influenza virus. Influenza mutates like crazy in general, but what’s specifically become possible with the H5N1 virus is this - an extremely lethal virus (50% mortality) which is not contagious between humans, may at some point end up in the body of a person with a typical influenza virus that is extremely contagious, and you get an extremely lethal, extremely contagious progeny.

Or another option is, the H5N1 may mutate on its own to become considerably more contagious to humans while retain its lethality. The more birds that come down with H5N1 (and there are billions of birds in the area where it’s become epidemic), the more likely this scenario is.

Or of course, you could have a new influenza strain mutate out of the blue from one of the other strains - but that probabilty hasn’t changed in the last ten years. At least AFAIK.

Now, it’s a lot more probable than 10 years ago. But does that mean it’s very probable in an absolute sense? I don’t know, and I haven’t seen anybody willing to put any kind of a number on it.

“Be Prepared”
Flu is generally seasonal. Some years are predictably more likely to have more flu than others. There are worse things than a bad case of flu but I can’t think of one at the moment.

You have some huge jumps to conclusions here resting on tenuous ideas to begin with. You didn’t show that any of these are fundamentally different now than ten years ago. More importantly, even if fewer people have health insurance now, modern medicine still can’t treat the flu directly so that isn’t necessarily a logical train of thought. You would need to show that the number of flu shots administered is going down among certain groups and that isn’t necessarily the case if there are many more being give out cheaply or free than there were back.

I also know of no data to suggest that we are becoming more urbanized in ways that would impact flu transmission. Urban and suburban sprawl suggests the opposite. A slightly growing population is taking up a now disproportionate amount of space meaning that people are more spread out. This is certainly the case since, say, the early 20th century when people packed into urban areas and even since the 1950’s when larger families lived in smaller houses.

I personally believe the threat has always been there and, while it will come out to kill us one day, there is no way to predict when and certainly no reason to believe that we are becoming more at risk in the First World than we were a few years ago.

:rolleyes: I don’t think this is the variety of flu folks are worried about… Nor do I see health coverage as the key component of the problem.

-XT

There is a very good and specific reason to believe we are more at risk. See my post. Two above yours.

Would it be fair to say that there does seem to be a cycle of high mortality flu, and that every year there isn’t an epidemic brings us closer to the year that it does happen?

Ok, I will have to take your word on the bird flu risk. I was referring more to human lifestyle factors that would increase the likelihood of a large epidemic from our end.

Air travel. With a current incubation period of three to seven days for avian influenza, how many thousands of people could enter this country potentially carrying the bug before it is detected? At our avian flu seminars last spring we were told more than 4,000 people enter the US each day on the west coast via international flights from potential hot spot areas in Asia.

The big difference is that there is now an existing flu virus that has an extremely high mortality rate. Most flu viruses have a mortality rate of 1% or less. As uglybeech wrote, the Avian Flu virus has a mortality rate of approximately 50%. If it mutates into an easily human contagious virus (which does happen) without losing its lethality, it will be one of the worst disasters in human history.

What Little Nemo said.

How to put this as simply as possible?

[ul]10 years ago H5N1 had not jumped to humans.[/ul]
[ul]10 years ago it was not endemic among ginormous populations of birds across Asia.[/ul]

We don’t really know the human mortality rate of H5N1

In the areas where it has been reported, there is not exactly close monitoring.

One could say that 50% of people hospitalized with H5N1 died …

As for the original question, well each year that we do not get a 1918 type infection makes it all the more likely that one will turn up

  • or is it a gambler’s fallacy, and the roulette ball will always land on black ?

Killer flu pandemics, which is what we should really be concerned with, tend to go in cycles because after each such event there is a high level of resistance in the remaining population. Above some critical level of resistance an outbreak is unlikely to take hold in the population at large. As the those in population with resistance die off through other causes and the proportion with no resistance rises, the likelihood of a pandemic rises also.

It has not been demonstrated that the bird flu has a mortality rate of 50%. That still might be true but the only thing that has been demonstrated is that among people who get sick enough to go to a hospital and to have a definitive diagnosis, the mortality rate is 50%. That is a far different claim since most people with upper respiratory infection never even see a doctor.

It is conceivable that only, say 10%, of the population has the right genetic makeup to be susceptible to the 50% mortal form of infection. It could be 1%, it could be 99%, no one knows at this point.

In general, I think that the arrival of a world-wide pandemic is a random event, essentially unpredictable. The existence of bird flu certainly changes the odds. The fact that people move much farther and much faster than they used to means that any pandemic will travel further and faster, but won’t change the likelihood of its happening at all.

This is really just speculation that’s being less and less borne out by the data. Overall, serological testing of people in affected areas has not shown significant mild or asymptomatic illness, and most epidemiologists are no longer banking on there being large populations of mild cases.

It is hard to prove a negative, though. If there are just 250 undiagnosed mild illnesses worldwide (and no undiagnosed fatal ones), that would lower the actual fatality rate to 25%. But I think you have to wrap this uncertainty into the total uncertainty you attach to any epidemiological statistic. Yes, it’s impossible to say for sure that what the absolute mortality rate is, and even more unknown is what any pandemic strain would look like. But right now the bird flu *looks * very lethal, and it probably is.

As for transmissibility, you’re right, it’s very clear that H5N1 is very very hard to get. Even if I were a chicken plucker in Indonesia, I wouldn’t lose any sleep over catching the current strains of H5N1. But that technically doesn’t lower its *mortality * rate. The fact that it’s not very transmissable is precisely why we don’t have an epidemic yet. Pandemic is just a risk, not an inevitability.

Well, sure it will.

… assuming one knows the definition of the word “pandemic.”