Originally Posted by Rrrrrachel
Data on disease incidence isn't enough on it's own. Experimental data and clinical trials are part of the picture, too, and necessary for establishing causation.
In the first graph, I think you're getting to caught up in the details instead of the overall trend. Some variation from year to year doesn't mean the overall trend isn't decreasing. But, like i said, that's why it's there for people to see for themselves.
I understand what you're saying about an overall trend but the original question I had was why "correlation equals causation." For example, TB is on the decline in the U.S. and I'm sure if I poked around I could find other diseases that have declined or disappeared over time.
I've been doing my best to look at experimental data, also. For example, when the CDC reported the switch to the acellular pertussis vaccine, they reference studies that indicate increased efficacy of the acellular version compared to the older whole cell vaccine but now I'm reading that the outbreaks may be due to the decreased efficacy of the newer version. Which is it? If you'd like to point me to studies or clinical trials that you think are relevant, I will look at them. I want to understand and it's nice to have both sides.
In the interim, here is only the first bullet from the second link you posted because that's all I've had time to look at.
“Before 1985, Haemophilus Influenzae type b (Hib) caused serious infections in 20,000 children each year, including meningitis (12,000 cases) and pneumonia (7,500 cases). In 2002, there were 34 cases of Hib disease.”
I followed the reference to the CDC website and found an incredible amount of information abount Hib (so thank you). I learned that that first bullet on the second link you sent me is misleading. Here are some of the things I learned:
Haemophilus influenza did not become nationally reportable until 1991 so the number above (20,000/yr) is an estimate only and is an estimate of ALL H. influenza – not just type b which is what the vaccine targets. As stated in my previous post, the numbers for all types once they began reporting in 1991 ranges between 1,000-3,000 with last year being the highest yet at 3,184. This makes me wonder why we aren’t hearing all over the news about the H. influenza outbreak of 2011.
They say that between 1996-2000, they could identify 76% of the serotypes that occurred but then in 2009, the wording is different so it’s not clear but it looks like there are now higher number of serotypes that are unknown, which would lead me to believe they are mutating? Here is the wording: “35 cases of invasive disease due to Hib were reported…In addition, another 178 cases caused by unknown H. influenza serotypes.
They also note that between 1996-2000, “32% of children aged 6-59 months with confirmed type b disease had received three of more doses of Hib vaccine, including 22 who had received a booster dose 14 or more days before onset of their illness. The cause of Hib failure in these children is unknown.” On the same CDC page, it says, “Invasive Hib in a completely vaccinated infant is uncommon.” So, 32% is uncommon?
Other quotes about H. influenza that I found interesting: “The primary mode of Hib transmission is presumably by respiratory droplet spread, although firm evidence for this mechanism is lacking.” And “The contagious potential of invasive Hib disease is considered to be limited.”
“Efficacy studies have not been performed in populations with increased risk of invasive disease.” This is absurd to me because shouldn’t the vaccines be targeting high-risk populations?
Another note, the original vaccine “…was not effective in children younger than 18 months of age. Estimates of efficacy in older children varied widely, from 88% to -69% (a negative efficacy implies greater disease risk for vaccinees than nonvaccinees). HbPV was used until 1988…” In fact, it looks like there were a few vaccines with low efficacy. Note --- according to what I've read, this would have only passed FDA approval with rigorous clinical trials and studies. How then is there such a discrepancy in effectiveness?
I only had time to explore the first bullet of the second link so this will obviously keep me busy for a while. I’m going to peek at the third link you sent.