The Hib vaccine is not required for school, so it an optional vaccine, even for those who believe in full, on schedule, vaccination.
It is an inactive vaccination, which means that they kill the virus before injecting it. This means that it is a reletively safe in that regard (you're not terribly likely to catch the actual disease from the vaccination). However, the vaccination also contains ethanol (toxic, a depressent and tranquilizer) and aluminum hydroxide (which causes constipation, loss of appitite, tiredness, and muscle weakness). Aluminum is also a heavy metal, and getting too much into your system at once will poison you; especially if you are small. This vaccine is also one (of several) which has been linked to increasing rates of Type1 Diabetes in children.
The first HiB vaccine came out in 1983, but was pulled in 1985, because it was not effective for children under 18 months old (which is when the primary danger is), and furthermore it actually caused a few cases of HiB. In 1990 a new HiB vaccine was licensed. The current vaccination is successful (gives immunity) approximately 93-95% of the time
It is on the schedule at 2m, 4m, 6m, 12-15m (booster) and 'catch-up' doses can be given up to age 3. If the child has not been vaccinated for HiB at all, and is over 15m, then the CDC says that one dose is considered sufficient for full vaccination. Doses must be a minum of 4 weeks apart, but 8 weeks apart is optimum. The last dose must be given after the age of 12m and must be a minimum of 8 weeks after the prior dose.
The CDC states that the HiB vaccine does not require booster doses (although one is on the schedule!!) It is not given to older children or adults. (We shall soon see why!)
HiB itself is NOT a type of flu, but is mis-named because the doctor who originally identified it thought that it was related to the flu which was going around at the time, and named it accordingly (Haemophilus influenza type B). Nobody has bothered to correct the name. In and of itself, HiB is really not dangerous, but has been found to lead to meningitis (inflamation of the brain), which, of course, is dangerous. HiB was almost unknown until recent decades, and the medical community believes that it is probalby the result of a mutation of an older bacteria, and that the mutation probably resulted from increasing usage of antibiotics. HiB is usually ampicillin-resistent--a confirmed example of mutation and resistence to antibiotics. (Yes, boys and girls, we are making super bugs now.)
Risk factors for Hib include: weak or weakened immune system, poor diet, being in daycare, smoking (including second-hand smoke), bad housing/living conditions, and not being breastfed. The risk of getting HiB is also somewhat increased during the 7 days immediately following a HiB vaccination. HiB is almost unheard of among breastfed, non-daycare children (whether vaccinated or not). Getting an invasive (ie-serious) infection of HiB is very rare even among higher risk groups. (In other words, even if you get it, you will most likely just get a really mild case.) HiB is most common around 6-7m old, and is virtually non-existent in children over the age of 5.
Prior to the invention of the HiB vaccination, most children acquired natural immunity by 5 or 6, via asymptomatic infection (ie, they got the virus but had no symptoms or 'sickness' from it).
One interesting observation is that HiB via vaccine introduces only one type of antibody, whereas natural HiB introduces several types, and may provide more complete protection than the vaccine is able to.
There you have it. That is the research.
My conclusion? Unless the baby will be in daycare, or will not be breastfed, there is not much point in getting this vaccine. If your child is in a low risk group, and since getting the vaccine increases the risk of infection, I would venture to say that for some people getting the vaccine may actually make them more likely to get HiB than if they did not get it. Something to think about! If you do want to get it, your child can get 'fully vaccinated' in just one dose (rather than four) if you do it at age 15m or later. However, since the primary risk is around age 6m, is there a point in vaccination at 15m?!