BCG VACCINE for percutaneous use, is an attenuated, live culture preparation of the Bacillus of Calmette and Guerin (BCG) strain of Mycobacterium bovis.1 The TICE® strain used in this BCG VACCINE preparation was developed at the University of Illinois from a strain originated at the Pasteur Institute.
The medium in which the TICE® BCG organism is grown for preparation of the freeze-dried cake is composed of the following ingredients: glycerin, asparagine, citric acid, potassium phosphate, magnesium sulfate, and iron ammonium citrate. The final preparation prior to freeze drying also contains lactose. The freeze-dried BCG preparation is delivered in vials, each containing 1 to 8 — 108 colony forming units (CFU) of BCG which is equivalent to approximately 50 mg wet weight. Determination of in-vitro potency is achieved through colony counts derived from a serial dilution assay. Intradermal guinea pig testing is also used as an indirect measure of potency.
Reconstitution requires addition of Sterile Water for Injection, U.S.P. at 425°C (3977°F). For an adult dosage, 1 mL of Sterile Water for Injection, U.S.P., should be added to one vial of vaccine. For a pediatric dosage, 2 mL of Sterile Water for Injection, U.S.P., should be added to one vial of vaccine (see DOSAGE AND ADMINISTRATION).
No preservatives have been added.
Tuberculosis (TB) is primarily an airborne communicable disease caused by the bacterium, Mycobacterium tuberculosis.
Tuberculosis is an important global public health problem with an estimated 810 million cases and 23 million deaths occurring each year.2 The control of TB in the United States has been a constant challenge particularly with the resurgence in TB in the late 1980s and the early 1990s. In the United States, TB had declined approximately 6% per year since nationwide reporting began in 1953. However, in 1985 there was a 1.1% increase over the previous year. This upward trend continued through 1992, when the incidence was 10.5 cases per 100,000 population. In 1993, there was a 5.2% decrease over 1992 with a rate of 9.8 cases per 100,000 population.3 In 1997, the total TB cases reported was 19,855 or 7.4 cases per 100,000 people. This incidence rate represented the fifth consecutive year that number of reported TB cases had declined and a 26% decrease since the peak in 1992.4
In the 1990s, drug-resistant TB also became a significant public health concern. During the period of 19931996, in the United States, 13.1% of TB patients were infected with TB strains that were resistant to at least one drug used as first-line treatment for TB (isoniazid, rifampin, pyrazinamide, ethambutol, and streptomycin) and 2.2% of TB patients were infected with TB strains that were multiple drug resistant (MDR as defined by resistance to both isoniazid and rifampin). Cases of MDR-TB were reported from 42 states and Washington D.C. during this time period.5
Most persons infected with M. tuberculosis remain infected for many years by developing latent infections. Active TB will reactivate during the lifetime of 515% of infected patients who are immunocompetent. In general, active TB is fatal for about 50% of persons who have not been treated.3 The greatest known risk factor for developing active TB disease is immunodeficiency, particularly if caused by coinfection with HIV.4 Persons infected with HIV are estimated to be over one hundred times as likely as uninfected persons to develop TB, primarily as a result of reactivation of a latent TB infection.6 Other groups at high risk for developing TB include foreign-born individuals and persons in institutional settings such as correctional facilities, shelters for the homeless, and nursing homes.
Although over 2 billion people have been immunized with BCG, and it is currently an officially recommended vaccine in more than 180 countries, excluding the U.S., the efficacy of BCG as a vaccine against tuberculosis remains controversial. Prospective vaccine efficacy trials have shown that the protective benefit of BCG (various strains from different manufacturers) against clinical TB was variable, ranging from 080%.7 A recent meta-analysis of data from 14 prospective trials and 12 case control studies concluded that the overall protective effect of BCG against tuberculosis infection was 50%.8 The reasons for the wide range of effectiveness seen in these studies are unknown but may be attributed to the following: vaccination was not allocated randomly in observational studies; there were differences in BCG strains, methods, and routes of administration; and there were differences in the characteristics of the populations and environments in which the vaccines were studied.9 Despite the conflicting results concerning prevention of pulmonary tuberculosis, it is widely acknowledged that immunization of infants with BCG lowers the risk of disseminated complications of this disease.
Estimates in areas where BCG vaccination is performed at birth indicate that the effectiveness of BCG in preventing childhood TB meningitis or miliary TB exceeds 70%.1015
In a prospective trial using the TICE® strain of BCG VACCINE, Rosenthal, et al., studied 1,716 vaccinated and 1,665 non-vaccinated infants, all born at the Cook County Hospital in Chicago and followed for 1223 years. The diagnosis of tuberculosis was made following a review of chest X-ray results and clinical findings. There were 17 cases of tuberculosis among the vaccinated (0.43/1,000/yr) and 65 cases in the nonvaccinated (1.7/1,000/yr); this is a reduction of 75% (p<0.001) in cases of tuberculosis. One death was attributed to tuberculosis in the vaccinated group with 6 deaths in the controls, or a reduction of 83%. There were 639 families in which there was a sibling in both the control and vaccination groups. Eight of the 790 vaccinated subjects developed tuberculosis as compared with 30 of the 945 controls (p<0.001). Thirteen cases of nonfatal tuberculosis developed in the control group that were 2 years of age and under, with none in the vaccinated group.
There were 3 deaths from tuberculosis in the control group that were less than 2.5 years of age (all had miliary tuberculosis with meningitis), with one death in the vaccinated group (meningitis). The infant who died in the vaccinated group had not converted to a positive PPD skin test at 6 months of age and was never subsequently revaccinated. Following a single vaccination, 99.3% of all infants studied became PPD positive, with 84.2% still being positive after 8 years.16
In a 1995 study of vaccine potency, 26 tuberculin negative subjects were vaccinated with BCG VACCINE (TICE® strain) and subsequent tuberculin conversion was monitored. Conversion from a negative to a positive skin test may be considered a surrogate indicator of potency and immunization efficacy of BCG Vaccines; however, the correlation between PPD conversion and vaccine effectiveness has not been established. Twenty-four (24) subjects returned for follow-up testing with PPD 10 tuberculin units (10 TU) 8 weeks after vaccination. Twenty-two (22) of the 24 subjects converted to positive (skin test reading >5mm induration at 48 hours) and 2 remained negative. The conversion rate was 92% and the average positive skin test reading was 15.5mm in induration.17
In a second study, 22 volunteers between the ages of 18 and 40 who were not health care workers, were not foreign born, were HIV negative, and were negative responders to a 10 TU PPD skin test were vaccinated with the standard dose of BCG VACCINE (TICE® strain). Eight weeks after vaccination the subjects returned for a 10 TU skin test. Twenty-one (21) out of 22 converted to PPD positive at a level greater than 5mm for a skin test conversion rate of 95%.17