What is the cause of transmission? I didn't ask about carriers...I asked about transmission. Transmission is the passing of something...and if your child is vaccinated...it can't be passed to them. That is why vaccination is important. It protects the person vaccinated from carriers. Since we don't have a cure to rid the world of pertussis...we rely on a vaccine to prevent the spread. If someone is vaccinated, there is no transmission...since the disease is not passed on to them.
That fact is that pertussis is basically a mild cold(as far as symptoms go). Expecting every adult with a mild cough to stay homebound is ridiculous...especially when a shot would give your child the protection needed to fight transmission is exposed.
The bolded is NOT true at all. Vaccines are not 100%. What happens with the pertussis vaccine is that it is not all that reliable as it is claimed to be - people contract it, but have very, very mild symptoms, so do not stay home, and spread it further. The Pertussis vaccine does NOT prevent the transmission of the disease.
Pertussis
http://www.ima.org.il/imaj/ar06may-2.pdf
Pertussis is considered an endemic disease, characterized by an epidemic every 25 years. This rate of exacerbations has not changed, even after the introduction of mass vaccination a fact that indicates the efficacy of the vaccine in preventing the disease but not the transmission of the causative agent (B. pertussis) within the population [19].
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http://www.cdc.gov/ncidod/eid/vol6no5/pdf/srugo.pdf
The effects of whole-cell pertussis vaccine wane after 5 to 10 years, and infection in a vaccinated person causes nonspecific symptoms (3-7). Vaccinated adolescents and adults may serve as reservoirs for silent infection and become potential transmitters to unprotected infants (3-11). The whole-cell vaccine for pertussis is protective only against clinical disease, not against infection (15-17). Therefore, even young, recently vaccinated children may serve as reservoirs and potential transmitters of infection.
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Case definition has been particularly problematic in all of the recent DTaP vaccine efficacy trials. For uniform comparative purposes a case definition was suggested by a WHO expert committee.39 This definition required 21 days of paroxysmal cough plus laboratory confirmation of pertussis in the subject or household contact. There are 2 problems with this definition. The first is that a substantial number of B pertussis infections in unvaccinated children are mild and would not meet the case definition. The second is that all pertussis vaccines tend to modify duration and severity of disease rather than completely preventing illness.18,2326-29,35,36,40 Therefore, the WHO definition has made all vaccines look better than they are and it has tended to obscure differences between vaccines.