This is a question I have at the end of our course: Given that the BCG is used in cancer treatment (both to boost the CTL function and increase the angry macrophages and to kill bladder tumors being the innocent bystander or battlefield), then how come it is not even included in the list of recommended childhood vaccines?
I can understand that TB is uncommon in US but since immune deficient people (eg AIDS patietnts) can develop the disease and be possible foci for its' spread, wouldn't that mean that an outbreak may occur ?
This is a good question, and there is not one simple answer. First, for a long time there has been very little TB in the US, and since the vaccine is not as easy to use as most others (you must make skin scratches, which leave a scar) many people decided it was not worth the benefit. Also, you lose the ability to monitor skin tests, as all vaccinated people should become positive for the DTH response. Finally, some early studies showed less protection for US populations than for others (Asia, Middle East), though there was no explanation for that difference.
ReplyDeleteAnother reason that the BCG vaccine is not universally used is that according to the World Health Organization (WHO), the BCG vaccine has a documented protective effect against meningitis and disseminated TB in children. However, it does not prevent primary infection and, more importantly,
ReplyDeletedoes not prevent reactivation of latent pulmonary infection, the principal source of bacillary spread in the community. Pulmonary disease and reactivation of latent disease is the typical presentation of TB in the US, therefore the impact of BCG vaccination on transmission of Mycobacterium tuberculosis is limited here and in other developed countries.
http://www.who.int/immunization/wer7904BCG_Jan04_position_paper.pdf
Thanks, StaceyM7630, for supplying some of the missing (to me!) explanations.
ReplyDeleteA recent report of a meeting in Siena, Italy, may interest readers: "A crisis of public confidence in vaccines." A group of experts tried to figure out why people don't trust vaccines. I think they got a lot of things right, but didn't get to it being part of general suspicion (rejection?) of science, e.g., global warming. Why do people say vaccine studies can't be trusted because the manufacturers must have influenced the conclusions, but then trust absolutely Wakefield's paper (with its unacknowledged funding by plaintiffs' lawyers) saying MMR causes autism? There must be more than anti-science here...
http://www.ncbi.nlm.nih.gov/pubmed/21148125