Bacillus Calmette-Guérin Revaccination Questionable with Low Tuberculosis Incidence

Abstract

Bacillus Calmette-Guerin (BCG) revaccination was discontinued in Finland in 1990. The objective of this study was to assess the impact of BCG revaccination of tuberculin-negative school-children in prevention of tuberculosis. The tuberculosis cases in 1990-1995 were calculated among age cohorts born 1979-1984 and no longer covered by the BCG revaccination program. Corresponding data were collected for comparison from the period of revaccination in 1980-1985 among age cohorts born in 1969-1974. The National Tuberculosis Register was reviewed in order to observe the tuberculosis trend since 1980 in the age groups of 10-14 and 15-19 yr. Three cases of tuberculosis have been registered among non-BCG-revaccinated children during 6 yr after discontinuation of the program, i.e., 2.23 cases (95% CI 0.72 to 6.90) per million person yr. The control group revealed five cases, 3.78 (95% CI 1.57 to 9.07) per million person yr. The relative risk of tuberculosis in non-BCG-revaccinated children is 0.59 (95% CI 0.14 to 2.47) compared with the control group. The incidence of tuberculosis has continued to decline among adolescents since 1980. The follow-up data confirm that the cessation of BCG revaccination program had no effect on the continuing overall decline of tuberculosis in Finland. The efficacy of BCG revaccination seems to be low or nonexistent in countries with low tuberculosis incidence.

Current status of new tuberculosis vaccine in children

“…92 To date, little data on the efficacy of BCG revaccination is available. [92][93][94] The first study to evaluate its efficacy was in Karonga District of Malawi.…”

Vacina BCG: via percutânea ou intradérmica?

“…Nevertheless, even in areas of extreme poverty and high levels of malnutrition, the BCG vaccine, administered during the first few months of life, offers protection against tuberculous meningitis. [34][35][36] There are no comparative studies of the effectiveness of BCG administration methods (BCG-ID and BCG-PC). 6,19 In the USA and United Kingdom, where the BCG-PC vaccine has been adopted, there are low incidences of tuberculosis and the disease is not considered a significant public health problem.…”

“…13,14,16,[29][30][31][32][33] In Japan, despite the BCG-PC vaccine being widely used, the incidence of tuberculosis is even lower than in the USA and there is currently debate on the need to maintain the vaccination program. 15,34 The studies of BCG-PC published in these countries, therefore, do not provide any data on the effectiveness of the vaccine.…”

“…19 A number of reasons, further to the methodological differences between studies, have been suggested as being responsible for the variations between vaccine effectiveness results obtained; of these, the most often quoted are quality and conservation of the vaccine (different vaccine strains, cold chain, ultra-violet light exposure), vaccine administration method, genetic and nutritional variations between populations, latitude, exposure to other mycobacteria and differences in the local prevalence of other diseases such as AIDS. [1][2][3][30][31][32][33][34][35][36][37][38][39][40][41][42] Until to the end of the seventies, comparative studies of the two techniques were based on in vivo immunoresponse evaluations (cutaneous delayed-type hypersensitivity response -DTH skin test response); more recently, data has been published from studies which have investigated the immunoresponse in vitro, by means of assaying number of the different cytokines produced by the Th1 and Th2 lymphocytes, which appear to have a closer correlation with protective immunization. 40…”

“…An analysis of comparative studies of BCG-ID and BCG-PC leads to the following conclusions: stimulation of a DTH skin test response and the production of cytokines associated with Th1 lymphocytes are more reliable with BCG-ID; 4,12,49 low dosages of the BCG vaccine are unreliable for inducing protective responses, as assessed by IF-γ production; 42 it is probable that the differences between the results found when comparing the two techniques are the result of the lower dosage inoculated percutaneously; [6][7][8][9][30][31][32][33][34][35][36][37][38][39][40][41][42] adverse events associated with BCG are most common in association with poor administration technique; 4,9,18 the use of scarring to test whether the vaccine has taken is only of use after BCG-ID since BCG-PC does not leave scars; 9,18,19 the presence of scars should be verified during infancy since the scar reduces in size over the years; 27,29 BCG-ID gives better protection against the more severe forms of the disease, which principally occur d u r i n g c h i l d h o o d , s u c h a s m e n i n g i t i s tuberculosa; 2,3,32,33,35 to date, there is no evidence to prove that revaccination is effective for increasing the levels of protection against tuberculosis afforded to adolescents and adults. 28,33,41,47 Recommendations In Brazil, increased vaccination coverage with BC...…”