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3j.5 What are some of the risks of the BCG vaccine?




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This article is from the Childhood Vaccinations FAQ, by Lynn Gazis-Sax lynng@alsirat.com with numerous contributions by others.

3j.5 What are some of the risks of the BCG vaccine?

It rarely has serious side effects. (See _AHFS Drug Information_ for a
list.) The most common reactions are local. More severe local
reactions include ulceration at the vaccination site, regional
lymphadenitis with draining sinuses, and purulent drainage at the
puncture site. The most serious reaction is disseminated BCG
infection; BCG osteitis of the epiphyses of the long bones,
particularly epiphyses of the legs, can occur from 4 months to 2 years
after vaccination. The rate varies from 0.01 cases per million
vaccinees, in Japan, to 32.5 and 43.4 cases per million vaccinees, in
Sweden and Finland, respectively. Reactions may be more frequent
among people with symptomatic HIV infection.

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From J Thompson (jet14@columbia.edu):

The main strategy of TB control in the US is monitoring those at
risk of
exposure to the disease for signs of TB infection. The main method
used is something called a "PPD" (which stands for purified protein
derivative, i.e. proteins purified from TB). A PPD is "placed"
(injected subcutaneously) and then the site of injection is monitored
(usually at 48 hrs. after the injection). Anyone who has mounted an
immune response to a TB infection will exhibit redness and swelling at
the site of the PPD injection (the criterion for calling a "true
positive" PPD is that the inflammation must be at least 10
mm. wide). Also, this reaction must take place at a 1-2 day delay to
be diagnostic for TB infection (anything sooner is allergy, not a sign
of infection).
OK, what does all this have to do with BCG? Well, BCG, since it is
very
similar to TB, can cause a positive PPD. Thus, widespread immunization
with BCG makes it more difficult to screen for TB, since the screening
will pull up many people who are not infected. The reaction due to BCG
drops over time, but it is still a problem, so that (combined with the
low effectiveness) has ruled out BCG in the US. Of course, now that
drug-resistant strains are becoming more common, opinions might
change...
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