The safety of influenza vaccine in clinically cured leprosy patients in China.

BACKGROUND: Leprosy is an infectious disease caused by the bacterium Mycobacterium leprae. Influenza vaccine is an important influenza prevention strategy and the preparations used display good safety and tolerability profiles. But the safety of applying influenza vaccine on the clinical cured leprosy patients is unclear. METHODS: We conducted an observational clinical study, in Wuhan between November 15, 2016 and March 1, 2017. Two groups of participants ≥50 years of age received a 0.5 ml dose of the inactivated split-virion trivalent influenza vaccine and a follow-up 28 days observation of any solicited and unsolicited adverse events. RESULTS: A total of 134 subjects were included in the study. The total rate of reactogenicity was 5.4% [2/37] in leprosy group and 15.5% [15/ 97] in control group, the difference of reactogenicity between two groups was not significant (p = 0.1522). For solicited injection-sites adverse events (AEs), 12.4% [12/ 97] participants in the control group reported of itching, pain, erythema, swelling or induration, and no participants in leprosy group reported of any solicited injection-sites AEs. For solicited systemic AEs, 7.2% [7 / 97] participants in the control group reported of fever, malaise or headache, and 2.7% [1 / 37] participants in the leprosy group reported of fever, statistic result showed that the difference was not significant (p = 0.4438). Unsolicited AEs was reported by one male aged 76, 4 hours after vaccination administration, his plantar ulcer area began bleeding. All AEs were grade 1 or grade 2, and no recurrence of lepra reaction, AEs leading to early withdrawal from the study, or deaths were reported in this study. CONCLUSIONS: To our knowledge, the present study is the first clinical study to evaluate the safety of influenza vaccine in clinically cured leprosy patients. We concluded that clinically cured leprosy patients are relatively safe for influenza vaccine. More importantly, our study make a positive and scientific efforts to eradicate discrimination on leprosy. In our study, we described a patient with plantar ulcer undergoing bleeding for 4 hours after vaccine administration. Based on evidence we have, we interpret that this adverse event may probably associated with vaccine, and patients with ulcer and leprosy need intensive attention after vaccines administration.

Immunogenicity and protective efficacy of "Mycobacterium w" against Mycobacterium tuberculosis in mice immunized with live versus heat-killed M. w by the aerosol or parenteral route.

As the disease caused by Mycobacterium tuberculosis continues to be a burden, there is a concerted effort to find new vaccines to combat this problem. One of the important vaccine strategies is whole bacterial vaccines. This approach relies on multiple antigens and built-in adjuvanticity. Other mycobacterial strains which share cross-reactive antigens with M. tuberculosis have been considered as alternatives to M. bovis for vaccine use. One such strain, "Mycobacterium w", had been evaluated for its immunomodulatory properties in leprosy. A vaccine against leprosy based on killed M. w is approved for human use, where it has resulted in clinical improvement, accelerated bacterial clearance, and increased immune responses to Mycobacterium leprae antigens. M. w shares antigens not only with M. leprae but also with M. tuberculosis, and initial studies have shown that vaccination with killed M. w induces protection against tuberculosis in Mycobacterium bovis BCG responder, as well as BCG nonresponder, strains of mice. Hence, we further studied the protective potential of M. w and the underlying immune responses in the mouse model of tuberculosis. We analyzed the protective efficacy of M. w immunization in both live and killed forms through the parenteral route and by aerosol immunization, compared with that of BCG. Our findings provide evidence that M. w has potential protective efficacy against M. tuberculosis. M. w activates macrophage activity, as well as lymphocytes. M. w immunization by both the parenteral route and aerosol administration gives higher protection than BCG given by the parenteral route in the mouse model of tuberculosis.

Vaccination against leprosy at Ben San Leprosy Centre, Ho Chi Minh City, Vietnam.

Three vaccines, BCG alone, BCG + 10(7) killed Mycobacterium vaccae and 10(8) killed M. vaccae alone, were studied in children living in close contact with leprosy. In the year before vaccination, 14/446 (3.1%) children had developed leprosy. Among those who were not vaccinated, 9/74 (12.2%) developed the disease in the first 4 years of the study and 5/65 (7.7%) developed the disease in the second 4 years. In comparison with this, among those vaccinated, 20/343 (5.8%) developed leprosy in the first 4 years and 5/323 (1.5%) developed leprosy in the second 4 years. This represents 52.5% protection in the first 4 years and 80.5% in the second 4 years. There were no significant differences in protection afforded by each of the three vaccines but the success of the killed preparation of M. vaccae is an important finding.

Antileprosy protective vaccination of sooty mangabey monkeys with BCG or BCG plus heat-killed Mycobacterium leprae: immunologic observations.

Groups of sooty mangabey monkeys (SMM) were vaccinated and boosted with Mycobacterium bovis bacillus Calmette-Guerin (BCG), or BCG + low-dose (LD) or high-dose (HD) heat-killed M. leprae (HKML), or were unvaccinated. Prior to and following vaccination-boosting and subsequent M. leprae (ML) challenge, these and unvaccinated, unchallenged control monkeys were immunologically observed longitudinally for approximately 3 years. SMM [multibacillary (MB) leprosy-prone as a species] were not protected clinically by BCG or BCG + HKML, although the disease progress was slowed by vaccination with BCG alone. The longitudinal immune response profiles to BCG or BCG + HKML in SMM showed that: 1) vaccination with BCG or BCG + HKML initially stimulated significant in vitro blood mononuclear cell blastogenic responses to ML antigens, which returned to baseline post-boosting and post-live ML challenge; 2) BCG + LD HKML-vaccinated groups gave the largest blastongenic response (SI = 23) followed by the BCG + HD HKML group (SI = 14.5) and by the BCG-only vaccinated group (SI = 3.6); 3) significantly diminished numbers of blood CD4+ (helper) and CD4+CD29+ (helper-inducer) T-cell subsets were observed longitudinally in all ML-challenged groups compared to controls regardless of whether they had been vaccinated or not; 4) CD8+ (suppressor) T-cell numbers remained longitudinally constant, on average, in all ML-challenged groups (vaccinated or not) compared to controls; 5) there was a significant decrease in the CD4+:CD8+ ratio over time in all ML-challenged groups (vaccinated or not); 6) vaccination with BCG or BCG + LD or HD HKML resulted in significantly increased numbers of CD4+CD45RA+ (suppressor-inducer) T cells longitudinally compared to the unvaccinated, ML-challenged control group; and 7) over time, vaccination with BCG + HKML followed by live ML-challenge produced higher IGM:IgG antiphenolic glycolipid-I (PGL-I) serum antibody response ratios than BCG-only vaccinated, ML-challenged monkeys or unvaccinated, ML-challenged SMM, consistent with prior observations that IgG anti-PGL-I responses correlate with resistance to and protection from clinical leprosy and IgM anti-PGL-I responses correlate with increased susceptibility.

Induction of lepromin positivity following immuno-chemotherapy with Mycobacterium w vaccine and multidrug therapy and its impact on bacteriological clearance in multibacillary leprosy: report on a hospital-based clinical trial with the candidate antileprosy vaccine.

A vaccine based on autoclaved Mycobacterium w was administered, in addition to standard multidrug therapy (MDT), to 157 bacteriologically positive, lepromin-negative, multibacillary (LL, BL and BB) leprosy patients. The vaccinees were supported by a well-matched control group of 147 patients with similar type of disease who received a placebo injection in addition to MDT. The MDT was given for a minimum period of 2 years and continued until skin-smear negativity, while the vaccine was given at 3-month intervals up to a maximum of 8 doses. The lepromin response evaluated in terms of percentage of subjects converting to positivity status, measurement in millimeters, and duration of lepromin positivity sustained, reflected a statistically significant better outcome in the vaccine group patients (especially LL and BL leprosy) in comparison to those in the placebo group. The data indicate that lepromin-positivity status seems to have an impact on accelerating the bacteriological clearance, as is evident by the statistically significant accelerated decline in the BI of those patients who converted to lepromin positivity as compared to those remaining lepromin negative throughout therapy and post-therapy follow up. To conclude, the addition of the Mycobacterium w vaccine to standard MDT induces a lepromin response of a statistically significant higher magnitude than that observed with MDT alone.

Protective immunization of monkeys with BCG or BCG plus heat-killed Mycobacterium leprae: clinical results.

Rhesus and sooty mangabey monkeys (RM and SMM) were vaccinated and boosted with BCG or BCG + low dose (LD) or high dose (HD) heat-killed Mycobacterium leprae (HKML). One group was not vaccinated. Except for a group of controls, all monkeys were challenged with live M. leprae. All animals were studied longitudinally to determine antileprosy protective efficacy. BCG reduced the numbers of RM with histopathologically-diagnosed leprosy by 70% and slowed and ameliorated the appearance of symptoms. BCG + LDHKML reduced the number of RM with leprosy by 89% and BCG + HDHKML by 78%. BCG did not protect SMM from developing leprosy, but disease progress was slowed; disease in SMM was exacerbated by the addition of HKML to the vaccine. RM, as a species, are prone to paucibacillary (PB) forms of leprosy, whereas SMM are prone to multibacillary (MB) forms. Thus, BCG vaccination offers significant protection from clinical disease and slows/ameliorates the rate of progression/degree of disease at the PB end and appears to at least ameliorate symptoms at the MB end of the leprosy spectrum. BCG + HKML protects at the PB end and exacerbates disease progress at the MB end of the leprosy spectrum.

Comparative leprosy vaccine trial in south India.

This report provides results from a controlled, double blind, randomized, prophylactic leprosy vaccine trial conducted in South India. Four vaccines, viz BCG, BCG+ killed M. leprae, M.w and ICRC were studied in this trial in comparison with normal saline placebo. From about 3,00,000 people, 2,16,000 were found eligible for vaccination and among them, 1,71,400 volunteered to participate in the study. Intake for the study was completed in two and a half years from January 1991. There was no instance of serious toxicity or side effects subsequent to vaccination for which premature decoding was required. All the vaccine candidates were safe for human use. Decoding was done after the completion of the second resurvey in December 1998. Results for vaccine efficacy are based on examination of more than 70% of the original "vaccinated" cohort population, in both the first and the second resurveys. It was possible to assess the overall protective efficacy of the candidate vaccines against leprosy as such. Observed incidence rates were not sufficiently high to ascertain the protective efficacy of the candidate vaccines against progressive and serious forms of leprosy. BCG+ killed M. leprae provided 64% protection (CI 50.4-73.9), ICRC provided 65.5% protection (CI 48.0-77.0), M.w gave 25.7% protection (CI 1.9-43.8) and BCG gave 34.1% protection (CI 13.5-49.8). Protection observed with the ICRC vaccine and the combination vaccine (BCG+ killed M. leprae) meets the requirement of public health utility and these vaccines deserve further consideration for their ultimate applicability in leprosy prevention.

Quality control tests for vaccines in leprosy vaccine trial, Avadi.

All the vaccines supplied for the large scale comparative leprosy vaccine trial of ICRC bacilli, M.w, BCG plus killed M. leprae (candidate vaccines), BCG and normal saline (control arms) at CJIL Field Unit, Chennai were tested for quality control by the suppliers following the procedures laid down in the WHO protocol for killed M. leprae. Quality control for BCG was carried out at BCG vaccine laboratory as per protocol. Toxicity and sterility tests were done on all the vaccine batches/lots received. As part of the quality control, bacterial count, and protein estimation were also done. Studies showed that the bacterial content and protein concentration were comparable with the original preparations. Vaccines were free from micro-organisms, toxic materials and safe for human use. Thus the quality of all vaccine preparations was satisfactory.

A follow-up study of multibacillary Hansen's disease patients treated with multidrug therapy (MDT) or MDT + immunotherapy (IMT).

Multibacillary (MB) leprosy patients treated with multidrug therapy (MDT) or MDT + immunotherapy (IMT) with BCG + heat-killed Mycobacterium leprae were tested annually for their ability to proliferate in vitro to the mycobacterial antigens BCG, M. leprae soluble extract, and intact M. leprae. IgM antibody responses to phenolic glycolipid I (PGL-I) were measured, as well as serum nitrite levels in patients' sera, before, during and after treatment. Patients who received only MDT did not present cellular reactivity to intact M. leprae antigens, in contrast to the results obtained with BCG, which elicited reactivity at time zero, that increased after treatment. Regarding PGL-I antibody variations in relation to the initial value, we observed a statistically significant marked decrease at the end of 2 years which continued to fall in successive evaluations. MB patients showed high initial serum nitrite concentrations which dropped drastically with treatment. This decay was apparently associated with the bacillary load present in these patients. The group submitted to IMT + MDT showed high and long-lasting T-cell responses to mycobacterial antigens in a significant number of initially unresponsive MB patients. There was a marked increase to M. leprae soluble extract and BCG, as well as a more variable response to whole bacilli. The antibody levels in this group of patients are sustained for a somewhat longer period and decreased more slowly during the 5-year follow up.

Regional lymphadenitis following antileprosy vaccine BCG with killed Mycobacterium leprae.

Phase-II and extended Phase-II studies were conducted in three different sets of the population in Thiruthani Taluk, Chengalpattu District, South India, involving BCG and killed Mycobacterium leprae (KML) combination vaccines to ascertain the acceptability of the vaccines. In the Phase-II study, 997 healthy volunteers were vaccinated on individual randomization with one of the vaccines arms: BCG 0.1 mg + 6 x 10(8) KML, BCG 0.1 mg + 5 x 10(7) KML, BCG 0.1 mg + 5 x 10(6) KML, BCG, 0.1 mg or normal saline. Blood samples were taken and the serum was tested for antibody levels against phenolic glycolipid-I (PGL-I) and the 35-kDa protein of M. leprae. In this study, we observed regional suppurative adenitis in 6% (6 out of 100), 3% (3 out of 100), and 3% (3 out of 100) of the vaccinees in the BCG 0.1 mg + 6 x 10(8) KML, BCG 0.1 mg + 5 x 10(7) KML, and BCG 0.1 mg + 5 x 10(6) KML vaccine arms, respectively, in the 13-70 year age group. Earlier BCG scar status, skin-test reactions to lepromin-A, Rees' MLSA, and serum antibody levels against PGL-I and the 35-kDa protein did not help to identify the group at risk of developing suppurative adenitis. Suppurative adenitis appears to have a different relationship between the age of the subject and the dose of the vaccine. In order to overcome the problem of regional suppurative adenitis and to know the mechanism involved, an extended Phase-II study was conducted in similar groups of the population by reducing the BCG and KML doses, i.e., with BCG 0.05 mg + 6 x 10(8) KML, BCG 0.05 mg + 5 x 10(7) KML, and BCG 0.01 mg + 5 x 10(7) KML. Biopsy specimens were collected from lymph nodes of the suppurative adenitis cases and were subjected for culture and histopathological examination. The observations showed that regional suppurative adenitis could be reduced to 1% in the BCG 0.05 + 6 x 10(8) KML group, 0.5% in the BCG 0.05 + 5 x 10(7) KML group, and 0.5% in the BCG 0.01 + 5 x 10(7) KML group. This phenomenon of suppurative adenitis appears to be related to the total dose of mycobacterial antigens. Suppurative adenitis was seen by weeks 18 and 20 post-vaccination in the latter two lower doses; whereas it was seen by week 8 in the higher dose of the combination vaccines. No case of suppurative adenitis was observed in the BCG 0.1 mg group. Culture and histopathology ruled out the possibilities of progressive BCG infection and superadded infection. Considering the above results, BCG 0.05 mg + 6 x 10(8) KML was acceptable for a large-scale vaccine trial in South India.

Immunotherapy of lepromin-negative borderline leprosy patients with low-dose Convit vaccine as an adjunct to multidrug therapy; a six-year follow-up study in Calcutta.

The present report, which describes management of lepromin-negative borderline leprosy patients with low-dose Convit vaccine, is an extension of our earlier study on the treatment of lepromatous leprosy patients with low-dose Convit vaccine as an adjunct to multidrug therapy (MDT). The test Group I, consisting of 50 lepromin-negative, borderline leprosy patients, were given low-dose Convit vaccine plus MDT. The control group II consisted of 25 lepromin-negative, borderline leprosy patients given BCG vaccination plus MDT and 25 lepromin-negative, borderline leprosy patients given killed Mycobacterium leprae (human) vaccine plus MDT. The control group III consisted of 50 lepromin-positive, borderline leprosy patients not given any immunostimulation but given only MDT. Depending upon the lepromin unresponsiveness, the patients were given one to four inoculations of the various antileprosy vaccines and were followed up every 3 months for 2 years for clinical, bacteriological and immunological outcome. All patients belonging to the test and control groups showed clinical cure and bacteriological negativity within 2 years. However, immunologic potentiation, assessed by lepromin testing and the leukocyte migration inhibition test (LMIT), was better in the test patients receiving low-dose Convit vaccine plus MDT than in the control patients receiving BCG vaccine plus MDT or killed M. leprae vaccine plus MDT or MDT alone. But the capacity of clearance bacteria (CCB) test from the lepromin granuloma showed poor bacterial clearance in the test patients. However, there was no relapse during 6 years of follow up. Two mid-borderline (BB) patients had severe reversal reactions with lagophthalmos and wrist drop during immunotherapy despite being given low-dose Convit vaccine.

Restoration of proliferative response to M. leprae antigens in lepromatous T cells against candidate antileprosy vaccines.

Several studies conducted in the last decade suggest that Mycobacterium lepraereactive T cells exist in lepromatous patients, but their number may be too few to yield a detectable response in cell-mediated immunity (CMI) assays. Immunizations with candidate antileprosy vaccines and stimulation of T cells with M. leprae + interleukin-2 restore the M. leprae-induced CMI response in lepromatous leprosy patients. These immunizations and stimulation may enrich the pre-existing M. leprae-responsive T cells in lepromatous patients and, thereby, induce a detectable CMI response to M. leprae antigens upon repeat testing. To verify this proposition, we carried out a study in a group of 10 lepromatous leprosy patients. Peripheral blood mononuclear cells (PBMC) obtained from these patients were anergic to M. leprae antigens in proliferative assays, but they responded to the antigens of candidate antileprosy vaccines, i.e., M. bovis BCG, M. bovis BCG + M. leprae, and Mycobacterium w. The enrichment of M. leprae-responsive T cells was performed by establishing T-cell lines from the PBMC after in vitro stimulation with M. leprae, M. bovis BCG, M. bovis BCG + M. leprae, and Mycobacterium w. When tested for their proliferative responses, 1/10, 3/10, 6/10 and 2/10 T-cell lines established against M. leprae, M. bovis BCG, M. bovis BCG + M. leprae, and Mycobacterium w, respectively, responded to M. leprae. These results suggest that enrichment of pre-existing M. leprae-responsive T cells may contribute to the restoration of the T-cell response to M. leprae in some lepromatous patients. Four of the 10 M. leprae-induced T-cell lines proliferated in response to the 65 kDa, 36 kDa, 28 kDa, and 12 kDa recombinant antigens of M. leprae, suggesting that the nonresponsiveness of T cells in some lepromatous patients may be overcome by using recombinant antigens of M. leprae.

Randomised controlled trial of single BCG, repeated BCG, or combined BCG and killed Mycobacterium leprae vaccine for prevention of leprosy and tuberculosis in Malawi. Karonga Prevention Trial Group.

BACKGROUND: Repeat BCG vaccination is standard practice in many countries for prevention of tuberculosis and leprosy, but its effectiveness has not been evaluated. The addition of Mycobacterium leprae antigens to BCG might improve its effectiveness against leprosy. A double-blind, randomised, controlled trial to evaluate both these procedures was carried out in Karonga District, northern Malawi, where a single BCG vaccine administered by routine health services had previously been found to afford greater than 50% protection against leprosy, but no protection against tuberculosis. METHODS: Between 1986 and 1989, individuals lacking a BCG scar were randomly assigned BCG alone (27,904) or BCG plus killed M leprae (38,251). Individuals with a BCG scar were randomly allocated placebo (23,307), a second BCG (23,456), or BCG plus killed M leprae (8102). Incident cases of leprosy and tuberculosis were ascertained over the subsequent 5-9 years. FINDINGS: 139 cases of leprosy were identified by May, 1995; 93 of these were diagnostically certain, definitely postvaccination cases. Among scar-positive individuals, a second BCG vaccination gave further protection against leprosy (about 50%) over a first BCG vaccination. The rate ratio for all diagnostically certain, definitely postvaccination cases, all ages, was 0.51 (95% CI 0.25-1.03, p = 0.05) for BCG versus placebo. This benefit was apparent in all subgroups, although the greatest effect was among individuals vaccinated below 15 years of age (RR = 0.40 [95% CI 0.15-1.01], p = 0.05). The addition of killed M leprae did not improve the protection afforded by a primary BCG vaccination. The rate ratio for BCG plus killed M leprae versus BCG alone among scar-negative individuals was 1.06 (0.62-1.82, p = 0.82) for all ages, though 0.37 (0.11-1.24, p = 0.09) for individuals vaccinated below 15 years of age. 376 cases of postvaccination pulmonary tuberculosis and 31 of glandular tuberculosis were ascertained by May, 1995. The rate of diagnostically certain tuberculosis was higher among scar-positive individuals who had received a second BCG (1.43 [0.88-2.35], p = 0.15) than among those who had received placebo and there was no evidence that any of the trial vaccines contributed to protection against pulmonary tuberculosis. INTERPRETATION: In a population in which a single BCG vaccination affords 50% or more protection against leprosy, but none against tuberculosis, a second vaccination can add appreciably to the protection against leprosy, without providing any protection against tuberculosis.

Sensitization potential and reactogenicity of varying doses of BCG plus killed Mycobacterium leprae: an extended study.

This study is an extension of a previous study on an antileprosy combination vaccine of BCG plus killed Mycobacterium leprae (KML) regarding its sensitization potential and reactogenicity. The study was extended to see if by reducing the dose of BCG in the combination vaccine the incidence of suppurative adenitis could be reduced without a significant reduction in the level of postvaccination skin-test responses. The study included 860 individuals, and three preparations of the combination vaccine [BCG 0.05 mg + 6 x 10(8) KML (I), BCG 0.05 mg + 5 x 10(7) KML (II), BCG 0.01 mg + 5 x 10(7) KML (III)] along with normal saline (i.v.) were used. Each individual received one of these four preparations by random allocation. They were also tested with Rees' M. leprae soluble antigen (MLSA) and lepromin A 12 weeks after vaccination. Reactions to the MLSA were measured after 48 hr; reactions to lepromin A after 48 hr and 3 weeks. The character and size of the local response at the vaccination site were recorded at the third, eighth, and 15th week postvaccination. The results of the study showed that by halving the dose of BCG in the combination vaccine BCG plus 6 x 10(8) KML a) the incidence of suppurative regional adenitis was reduced significantly, b) there was no significant change in the post-vaccination response at 12 weeks as measured by Rees' MLSA and lepromin A, and c) the evolution of the vaccination lesion was somewhat prolonged. This dose was found satisfactory for use in a comparative antileprosy vaccine trial in South India.

Lepromin responses in recipients of a candidate antileprosy bacterin vaccine (WHO-IMMLEP Mycobacterium leprae killed preparation) in the USA.

BACKGROUND: Identification of the nine-banded armadillo as a potential source of massive numbers of Mycobacterium leprae led to the development of a candidate bacterin vaccine for possible immunoprophylaxis. METHODS: Volunteers were from a leprosy-hypoendemic, nonBCG-using area (USA). They had been vaccinated intradermally 3 years earlier with a candidate antileprosy bacterin vaccine of irradiated and autoclaved Mycobacterium leprae obtained from experimental nine-banded armadillos. They were tested for dermal responsiveness to standard lepromin A. RESULTS: Values for induration and erythema appeared slightly greater for the vaccinated group; however, the differences were not statistically significant, indicating no appreciable 'anamnestic' effect on either Fernandez (early) or Mitsuda (late) reactions after 3 years. CONCLUSIONS: Because previous studies had demonstrated that administration of this bacterin produced no humoral changes, it now appears less probable that laboratory methods will be of much help in assessing even possible effectiveness of such vaccination.

Sensitization potential and reactogenicity of BCG with and without various doses of killed Mycobacterium leprae.

A study was conducted in 997 individuals in two villages in south India to find the acceptability and sensitizing effect of the antileprosy combination vaccine of BCG plus killed Mycobacterium leprae (KML). Three preparations of the combination, BCG 0.1 mg + 6 x 10(8) KML (I), BCG 0.1 mg + 5 x 10(7) KML (II), and BCG 0.1 mg + 5 x 10(6) KML (III), along with BCG 0.1 mg (IV), and normal saline (V), were used in the study. Each individual received one of the above five preparations by random allocation. They were also tested with Rees' M. leprae soluble skin-test antigen (MLSA) and lepromin-A, both at intake and 12 weeks after vaccination. Reactions to Rees' MLSA were measured after 48 hr; those to lepromin-A after 48 hr and 3 weeks. The character and size of the local response at the vaccination site were recorded at 3, 8, 12, 15, and 27 weeks after vaccination. The mean sizes of postvaccination sensitization to both Rees' MLSA and lepromin-A in the vaccine groups were significantly larger than those in the normal saline group, clearly demonstrating the ability of the vaccines to induce sensitization as measured by responses to the two skin tests. The sensitizing effect was the highest following vaccination with vaccine I. It was not significantly different for vaccines II, III, and IV, although, generally, a dose-response effect was observed. The sensitizing effect attributable to the vaccine was more clearly seen in children than in adults. The above conclusions were the same irrespective of which results were considered, reactions to Rees' MLSA or Fernandez or Mitsuda reactions to lepromin-A. A significant finding of the study was that at intake the Mitsuda reactions provided a measure of sensitizing effect due to vaccine. The healing of vaccination lesions was uneventful. In more than 90% of vaccinated individuals, the lesions had healed by the 12th week in vaccine groups II, III, and IV, and by the 15th week in vaccine group I. The results showed that vaccination with BCG or combination vaccines was equally safe in individuals with or without previous BCG scars. Thirteen persons, aged 10 years or older, developed suppurative lymphadenitis around the 8th week (7 in vaccine group I, 3 each in vaccine groups II and III). However, healing was prompt after drainage in these individuals.