The committee found that the evidence favored acceptance of a causal relation between diphtheria and tetanus toxoids and Guillain-Barré syndrome and brachial neuritis, between measles vaccine and anaphylaxis, between oral polio vaccine and Guillain-Barré syndrome, and between unconjugated Hib vaccine and susceptibility to Hib disease.
Weird isn't it? The old Hib polysaccharide vaccines caused Hib-specific immunosuppression in children given the vaccine so they became more susceptible to Hib disease. This effect was experimentally seen with larger doses of vaccine. There was some kind of inhibition that the vaccine produced causing vaccinees to be more susceptible to Hib disease a short time post-vaccination.
These vaccines are no longer in use as the conjugated vaccines have replaced them and do not produce the same effect.
I think you are confusing combination vaccine with conjugate vaccine. Hib is made as a conjugate (joining of different proteins) but is a Hib only vaccine, except for Pentacel (DTaP-Hib-IPV) or Comvax (Hib-HepB), those are combination vaccines. Conjugate vaccines are made with parts of other organisms, like diphtheria proteins or tetanus toxoids (a protein) in order to 'trick' the immune system into paying attention to the Hib proteins and making antibodies against them. Does that make sense?
yeah I would think you would WANT the conjugate vaccine to be the only one out there because this vaccine is the one that allows a child under 18 months to recognize the hib protein coat and create antibodies. Use any other vaccine from the past and you would leave that child unprotected, right?