Help me understand this about HIB vax

[cartersmom]

There is this huge debate going on on another board about whether or not the hib vax can cause hib disease.

The majority say no it can't because there is no actual bacteria in the vaccine, just the polysaccharide capsule. A few are saying that that the capsule is the virulent part of the vaccine. People oppsing this viewpoint: One person says

Virulence depends on a number of virulence factors. In Hib's case the virulence factor is called immune response inhibitor - that is the capsule that stops human immune system from "seeing" the bacterium. In Hib's case this cloaking is its primary success factor in causing disease - in other words this capsule is Hib bacteria's ace in the hole.
That doesn't mean that the disease is caused by the capsule.
Think of it like this: terrorists send anthrax in the mail with a regular envelope. The envelope looks normal and thus allows the pathogen (anthrax) to sneak past the postal service and the mail room guy. Once you open the envelope the pathogen can do its job. If you remove the pathogen from the envelope the envelope contains no ability to cause disease. That is how the capsule works - it is a cloaking delivery mechanism for HiB. The vaccine is made from this envelope - empty with no pathogen inside.


The other camp says
The envelope (polysaccharide capsule) per se is the PATHOGEN
Again, the polysaccharide capsule in the vaccine is the PATHOGENIC portion of the Hib bacteria---which needs to ride along with a protein--Tetanus Toxoid
This will prove the case that the polysaccharide capsule in Hib vaccine will OBVIOUSLY result to Hib disease which will lead to bacteremia and meningitis

"Virulence
Virulence, at least in the case of bacteremia and meningitis, is directly related to capsule formation. Virtually all of these infections are caused by the type b serotype, and its capsular polysaccharide, containing ribose, ribitol and phosphate, is the proven determinant of virulence. The capsule material is antiphagocytic, and it is ineffective in inducing the alternative complement pathway, so that the bacterium can invade the blood or cerebrospinal fluid without attracting phagocytes or provoking an inflammatory response and complement-mediated bacteriolysis. "

http://bioinfo.bact.wisc.edu/themicrobialworld/haemophilus.html

Im really trying to understand this but have become very confused. Can anybody clear this up for me. Im not sure if it's kosher to post the link to the entite thread on another bpard here so if you want to see the whole sordid debate Pm me I guess and ill tell you where it is going on. Otherwise any help in sorting this out for me would be very much appreciated!!

[Momtezuma Tuatara]

My problem is that that reads very clearly to me, so I can't see why you're confused...

I'm never interested in sordid debate, as often it's the debate that confuses, rather than factual information.

There are lots of haemophilus bacteria out there, without the capsule, but they too cause problems.

the person who said the capsule is the virulence factor is wrong, because were that a fact, then everyone who encountered capsulated hib in the past, would have succumbed to the infection of the bacteria within, but they don't. In fact, actual clincal infection is only around 1 per 100,000 per person in the medical literature.

The virulence factor, is actually the health of the recipient, or some instance at the point of infection, which causes a breach in the normal immune system. That can be bad diet, lack of sleep, constant stress...

In fact, the reason that children in daycare are far more susceptible to Hib, is not that they are cheek to jowl with other kids, but because the stress of being cheek to jowl, puts out high levels of cortisol, which suppresses the immune system, that stress makes those children more susceptible to serious infection. Not to mention crap food in some daycare centres with provided by parents, or the centre itself...

The original HIB vaccine, which was solely a polysaccharide vaccine made just with the capsule, absolutely caused Hib, and it did that by causing serious depression of the antibodies for 7 - 14 days after the vaccine, making the child more susceptible to Hib if they were exposed to it. I have all the documents about that.

The newer conjugated vaccine was made differently in order to try to eliminate that problem. I'm not convinced that it has done so, totally, ... but even that is irrelevant, because just as the "virulence" factor is actually a host factor, the same applies with the vaccine.

The majority of people will have no problems. Put them into a situation where their immune system is under relentless pressure and they will have problems.

[Momtezuma Tuatara]

I think the main issue here, is that you are still, for whatever reason, scared of Hib. Right?

[cartersmom]

I think the main issue here, is that you are still, for whatever reason, scared of Hib. Right?


I'm actually much less scared than I was before. The more I learn the less scared I am. I think the numbers the CDC puts out about the chances of kids getting HIB before thay are 5 years old is 1 in 200 is false. I think their formula for arriving at that number is ridiculous. I believe HIB becomes invasive only in a susceptible host. I think NOT vaccinating only HELPS by NOT destroying the immune system. Does it still scare me? I guess a little. Any thought of losing my son for any reason scares me, but am I obsessing about the HIB anymore no! As for the debate, I think what you said about it being the debate that is confusing. I agree. The more I read of this debate the more confused I get.

[Momtezuma Tuatara]

Simple answer. Don't read debate yet. Read facts, and work it out, and then you will just laugh when you see people letting of squibs.