immuno grad student wrote:
shit, the flu kills like 800,000 people a year anyway...what's another couple hundred thousand?
yet another example of the media hyping something that is already a "problem" (1 million deaths is not a lot and is normal) by using terms like "H1N1" and "swine flu" to drum up reactions from uninformed people.
The standard flu kills many people a year; for many it is part of the final straw, often because they get pneumonia and cannot recover.
The H1N1 virus has already killed as many people in the last three weeks of reporting (about a two week lag?) as the seasonal flu killed all last year and we are barely into the (standard) flu season. The total years lost to death are much higher because a lot more young people are dying from it that rarely died with the seasonal flu.
The characteristics are different and it is a little tricky trying to figure out what is going to occur. However, the pandemic flu planning that was spurred by the Avian (H1N5)
Here is a primer if you want to get a summary feel from an informed source that I know very well:
WHO’s Pandemic Phases:
Phase 1: No known infections in humans
Phase 2: Animal influenza is known to have caused infection in humans
Phase 3: Limited human transmission
Phase 4: Community-level outbreaks
Phase 5: Human-to-human spread in at least two countries in one region
Phase 6: Outbreaks in at least two regions (pandemic!)
CDC’s Response Stages
0: Domestic animal outbreak overseas
1: Suspected human outbreak overseas
2: Confirmed human outbreak overseas
3: Widespread human outbreaks in multiple locations overseas (pandemic!)
4: First human case in North America
5: Spread throughout United States
What’s Different about Swine Flu?
Planning assumptions based on avian flu:
Disease would start in animals
Disease would start in a remote at-risk region
We’ll watch it spread from animals to humans, and from remote regions to the U.S. (weeks!)
Reality of swine flu:
Disease outbreak was identified in people first
Disease may have been in U.S. prior to 2009
March 2009 outbreak in Mexico
91 confirmed U.S. cases by end of April 2009, and 11 countries affected (Phase 5!)
What’s Different about Swine Flu?
Not highly lethal!
Case fatality ratios:
Avian flu 50%!
1918 pandemic 2%
Swine flu ~0.4% or less
Seasonal flu <0.1% usually
Case fatality ratios similar to upper range of that for seasonal influenza (or less):
And relatively low hospitalization rates
Although some people do get extremely sick
Elderly (born before 1957?) at relatively low risk!
Appear to have some level of immunity
Still at high risk if they do get sick
“Most severe cases and deaths have occurred in adults under the age of 50”:
“In stark contrast with seasonal influenza, where 90 percent of severe and fatal cases occur in people 65 years of age or older”
Some surprises about vulnerable groups:
Certain medical conditions (asthma, diabetes, etc.)
Increased risk during pregnancy
Obesity frequently present in severe and fatal cases
Some healthy young people becoming severely ill:
Apparently due to viral pneumonia
Different patterns of spread:
Less mixing than assumed in epidemiological models
Disease seems to come in “bursts”:
High rate of infection on campuses at start of year
High rate of infection at some schools but not others
Wisconsin Dells schools closed in October due to flu:
Absenteeism rates of 10% or more at middle school and elementary schools
Large water parks in the Dells had no unusual pattern of employee absenteeism!
Areas hit hard in spring have relatively little flu now:
Areas that had big outbreaks in the spring, like New York, are seeing less swine flu now
Only 10 to 20 percent of New Yorkers were ill with flu last spring, but as many as 20 to 40 percent may have developed immunity
High levels of immunity may make the second wave of swine flu less extensive than expected
Similar experience in southern hemisphere:
The infection appeared to have a six-seven week ascent to peak (with fairly rapid decline thereafter)
This may be similar to what is seen during an average flu season
Swine flu peaked early and unexpectedly in mid July
This flu season has not been much worse overall than 2007
“Herd immunity” showing up earlier than expected:
In New Zealand, the pandemic began to decline even though only about 11% of the population had been infected
In Boston, an estimated 11% of teenagers got swine flu in spring, but schools and colleges services have reported little flu this fall
Only 10-20% of New Yorkers were sick with swine flu last spring, but up to 40% may have been exposed and become immune
Herd immunity will not prevent people from getting sick:
But may reduce the rate at which the disease spreads