It isn't less aggressive, though, it's MORE aggressive:
We present evidence that in the Netherlands the dramatic increase in pertussis is temporally associated with the emergence of Bordetella pertussis strains carrying a novel allele for the pertussis toxin promoter, which confers increased pertussis toxin (Ptx) production.' - they said it produces MORE toxin (that's from the CDC link I just showed you).
It also said:
Epidemiologic data suggest that these strains are more virulent in humans.
MORE virulent, MORE, not less. Think antibiotics and MRSA or head lice lotion and superbug headlice that aren't killed no matter what you do, if we are doing weed analogies :)
The other source I showed you says:
'In contrast, vaccination led to a 40-fold enhancement of B. parapertussis colonization in the lungs of mice. Though the mechanism behind this increased colonization was not specifically elucidated, it is speculated to involve specific immune responses skewed or dampened by the acellular vaccine, including cytokine and antibody production during infection. Despite this vaccine being hugely effective against B. pertussis, which was once the primary childhood killer, these data suggest that the vaccine may be contributing to the observed rise in whooping cough incidence over the last decade by promoting B. parapertussis infection. Highlighting the extreme consideration that should be exercised in future vaccine development, this work supports the use of vaccines that also target B. parapertussis as a potentially more efficient way to battle whooping cough.'
So they're saying that the vaccine has caused parapertussis and that scientists ought to be careful about this issue when making other vaccines...but they should now change the DTaP vaccine to include the para strain.
They did that with the pneumonia vaccine too because that was causing a surgence of a new serotype, 19a pneumonia. JAMA wrote:
'The rapid increase in multiresistant serotype 19A as a cause of invasive and respiratory pneumococcal disease has been associated in time with the widespread implementation of 7-valent pneumococcal conjugate vaccination (PCV-7) in several countries. A 2 + 1-dose PCV-7 schedule was associated with an increase in serotype 19A nasopharyngeal acquisition compared with unvaccinated controls.'
That's why they brought in 13 valent penumonia vaccine recently. I'm willing to bet that in another 10 years or so there will be even more aggressive strains so they'll have to invent a vaccine with even more strains. All we are doing is suppressing one disease to replace it with an even bigger, more virulant killer disease. Nature adapts and it has so far outwitted man's inventions every time.
'Here's an opportunity for you to adjust your belief to new evidence. It's what scientists, and science writers, do.'
I could say the same about you.
Oh, by the way, I love weeds. I have lots in my front garden. They've grown up by my front door and grown many beautiful, white flowers. They look lovely so I left them there :)