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The most recent guidelines on the control and prevention of tuberculosis1 recommend that “individuals working as health care workers, irrespective of age, who are previously unvaccinated and who are negative or Heaf grade 1 on tuberculin testing, should receive BCG vaccination”. The algorithm in fig 2 suggests that a health care worker without a BCG scar or documentation of prior BCG should be vaccinated if Heaf testing is negative or grade 1. Presumably the algorithm, but not the text, could apply to those previously vaccinated, but without a document or a scar.
Not infrequently, health care workers present for pre-employment screening with no BCG scar, a possible or doubtful history of prior BCG vaccination, almost always without documentation. The previous guidelines2 recommended that “individuals with a negative or grade 1 Heaf reaction should receive BCG vaccination” and “those without a satisfactory reaction require a further tuberculin test and, if this is negative, a second vaccination”. The latter advice does not appear in the 2000 guidelines.
It is sometimes argued that the risk of developing a nasty local reaction at a BCG re-vaccination site is not warranted by the additional protection against occupationally acquired tuberculosis, which may or may not be derived from repeated BCG vaccination. In practice, we tend to favour this approach and avoid (re-)vaccinating those who may have been previously vaccinated. This is contrary to the 1994 BTS guidance, but the 2000 guidelines are less clear on the issue of re-vaccination. Has the Joint Tuberculosis Committee changed its view?
authors' reply The Joint Tuberculosis Committee has not changed its view on the re-vaccination of health care workers with BCG. In 1994 BCG vaccination was only recommended for those without a prior BCG vaccination (usually with absence of a typical scar) who were tuberculin negative.1-1 In the 2000 evidence based guidelines BCG vaccination was again recommended only for those who did not have a definite BCG scar (as recorded by an experienced person) or documentary evidence of a prior BCG and were tuberculin negative.1-2 These recommendations are consistent. There is no evidence that re-vaccination in health care workers or others who have been given BCG vaccination effectively gives any additional protection. The only issue is what is to be taken as evidence of BCG vaccination. The best proof is a typical scar, but documentary evidence is also accepted. In the absence of either, in someone who states that they have been vaccinated, a risk-benefit assessment is effectively made.
The risk of vaccination in someone who has been vaccinated already is that they have an accelerated BCG reaction. Conversely, if a health care worker has not actually been vaccinated, they have no protection against tuberculosis if tuberculin negative, with an increased risk being shown.1-3 The Joint Tuberculosis Committee's judgement of this risk benefit analysis in 2000—as in 1994—was that, if BCG vaccination could not be proven to have been given, it should be given to tuberculin negative health care workers.