A study on acceptability of BCG vaccination, through specialised technicians in a population of 8350 residing in 8 villages of Channapatna taluk of Bangalore district, was carried out by National Tuberculosis Institute. Of the 1106 households satisfactorily interviewed, 956 (86.4%) had at least one child eligible for vaccination. For the purpose of analysis they were classified into three groups. Group I consisted of 312 (32.6%) households in which all children were vaccinated, Group II 270 (28.2%) where non-e of the children were vaccinated and Group III 374 (39.2%) households where only some of their children were vaccinated. Overall vaccination coverage was 52.7% with a range of 33.9% to 79.3%.

The reasons for refusing vaccination were studied. The caste, occupation, education etc., of the household did not have any influence on the refusals. When analysed according to the knowledge and opinion about vaccination it was observed that 55.9% of the children were not vaccinated because of the lack of knowledge in the group where no child was vaccinated. Even when 42% had favourable opinion about vaccination, 52% of the households did not vaccinate any of their children. The refusals were mainly due to (i) absence from the village on the day of vaccination, (ii) fear of prick. Among households where there was unfavourable opinion, all had refused due to fear. The reasons for accepting BCG vaccination were (i) the vaccination was done in the school and hence there was no option for the parents to accept or refuse, (ii) parents felt that the vaccination was good for children, (iii) parents knew that it would prevent TB.

Under the auspices of the Indian Council of Medical Research, a third assessment of the mass BCG campaign in India was carried out from 1955-58. It is a continuation of the work started by the WHO, of evaluating the level of allergy among groups vaccinated in the campaign. WHO team used 5 TU RT 14, 20, 21, while the present assessment team used 5 TU RT 22. A total of 18,367 school children distributed over 262 schools in 169 different localities were retested for post-vaccination tuberculin sensitivity. The groups were vaccinated in mass BCG campaign with 91 different batches of vaccine produced in Madras. The interval between vaccination and retest varied from 1½ to 42 months.

The mean size of reactions varied from 8.3 to 16.6 with overall mean of 12.5 mm. Less than 10% of the mean values were under 10 mm and less than 10% over 15 mm. Analysis also showed that BCG vaccination was responsible for an increase of 6-7 mm in the mean size of reaction over the pre-vaccination level of the non-infected. One third of the groups had their sensitivity increased upto 6 mm and two third by 7-11 mm. Comparing with the highest attainable degree of tuberculin sensitivity in the infected 1/3rd of the vaccinated group fell short of it by 5-9 mm, whereas 2/3rd were within 4 mm of this level. There is no appreciable difference in the post-vaccination allergy according to the state and prevalence of non- specific tuberculin sensitivity. However, there is an increase in allergising capacity of the BCG vaccine after introduction of modifications in the production procedures in 1955 and again in 1956 in the BCG Laboratory at Madras. Waning of allergy upto 20 months after vaccination and boosting thereafter probably due to super infection was also observed. Findings show that a large proportion of the vaccinated groups retested have achieved attainable allergy with the vaccine used. In view of the above, there is an urgent need to produce Freeze-Dried vaccine than the present liquid vaccine for achieving high levels of allergy.

Freeze-Dried vaccine holds out promise for use in the mass BCG campaign. A continued and expanded research is needed into the protective value of BCG vaccination with the level of allergy which the mass campaign can produce under the epidemiological circumstances existing in India and other technically developed countries.

During the 7th All India BCG Conference held at Ahmedabad in February 1965 various points regarding the technical aspects of BCG Campaign were put forward by the author of this article. The issues discussed were related to specific age group to be vaccinated; direct vaccination; vaccination of new-borns; techniques of testing, reading and vaccination; preservation of biologicals, Freeze-Dried vaccine; pilot and research studies; assessment and training.

Some of the suggestions given on the above aspects described briefly were: (1) Only 0-20 years might be taken up because that was the most vulnerable age group for infection from the natural sources. (2) Direct BCG vaccination in 0-20 years age group could be carried out in the first round followed by vaccination of population below 7 years of age (0-6 years) in the subsequent rounds. (3) Infant vaccination practiced at that time in some of the major cities only, would not contribute greatly to the control of tuberculosis unless it is extended to the rural areas also. (4) Results of vaccination should be exceedingly good provided vaccine was maintained properly, used within 2 weeks of manufacture, shaken well before opening, a drop ejected out before vaccination and proper dosage injected correctly. (5) The vaccine must be kept under refrigeration during storage, transport and use. (6) The personnel engaged in the use of Freeze-Dried vaccine had to be trained properly in its aseptic reconstitution. (7) Operational studies in respect of BCG work in cities; practicability and feasibility of setting up training centres in the states, assessment of programme by the states etc., were required to be undertaken. (8) Uniformity of techniques and procedures of BCG vaccination and proper assessment of Mass BCG Campaign by an independent agency would be required. The author in his article also stressed that no changes should be brought into operation without assessment.

BCG vaccination is being conducted as a mass campaign. It is difficult to maintain a high coverage of the population at risk i.e., new borns. This can best be done by integrating the BCG vaccination services with the general health services. The present investigation was planned to study the feasibility of routine BCG vaccination of the new borns by the Primary Health Centre personnel using the normal records maintained by them. In a rural population of 33,128 persons (1971 census), served by PHC Bettahalasur of Bangalore district, BCG vaccination was administered to 0-15 months old children by 2 Block Health Workers (BHWs) and 3 Auxiliary Nurse Midwives (ANMs) after training them for about 3 weeks. They used a compact specially designed BCG kit and employed a conventional intradermal technique for BCG vaccination. Routine work was not to be disturbed in any way. Each worker prepared a list of children eligible for BCG vaccination from the register of unprotected children and updated the list for those not found registered. National Tuberculosis Institute (NTI) field staff registered a sample population, allotted to each worker for estimation of eligibles. Three months later they also examined BCG vaccination lesions in a sample of children. BHWS and ANMS were interviewed by a medical officer from NTI regarding their opinion on integrated work.
The findings showed that the ANMS and BHWS had already registered nearly 50% of the new borns in their records with variation in registration from 21 to 80% by the field workers; ANMS understandably having registered lesser numbers. All of them were, however, able to update the registrations to a level of 82%. They could pick up the BCG vaccination technique easily. Of the total eligibles, ANMS and BHWS could contact 86.4% and vaccinate 77%; remaining 23% either refused or were excluded from vaccination. In the total eligibles registered, however, the vaccination coverage was 66.6%. Of the children reported vaccinated, 96% had evidence of BCG vaccination indicating a high degree of reliability of reporting. The opinion of all the 5 field workers on integration was favourable. All the ANMS and BHWS workers, on interview, stated that they had done BCG work without detriment to their other duties and would be easily able to do so in future. The field workers can accumulate the new borns for a year and vaccinate them during a month. This has mainly operational advantages including less vaccine wastage. For urban areas a different operational design with the same principles may become necessary.

After the introduction of direct BCG vaccination, assessment of post-vaccination allergy and information about prevalence of infection could not be obtained. Few methods were tested i.e., i) retesting of persons with 0-13 mm reaction at site of vaccination on 4th day of vaccination, ii) retesting of all vaccinated persons of age 0-10 years. It is not only necessary to find out the size of BCG lesion that could separate them but also the day after vaccination on which the tuberculin reaction size best correlates with the BCG vaccination size. With this in view, two studies with regard to direct BCG vaccination done in India have been examined further. In Study I, 816 eligible persons were tested with 1 TU RT 23 read on 3rd day and vaccinated with either Indian or Danish vaccine. The vaccination lesions were examined on the 3rd, 6th and 90th day of vaccination. On the 90th day post-vaccination tuberculin test was done and read on 3rd day. In Study II, a total of 691 who had no previous BCG scar were simultaneously tuberculin tested with 1 TU RT 23 and vaccinated with either Indian or Danish vaccine. The BCG lesions were examined every day and on 39th and 90th day.

The correlation of pre-vaccination tuberculin test and BCG lesion size showe d that sixth day in first study and fifth day in second study was the highest. Tuberculin reaction size of 10 mm or more correlated well with 14 mm or more induration size of BCG in classifying the persons as infected and non-infected. Correlation between the size of BCG scar at 3 months and size of pre-vaccination tuberculin reaction was poor. Considering the two studies together vaccination induration of 14 mm or more on 5th or 6th day appears to be the best criterion for demarcating the infected from non-infected. Some other choices are 12 or 14 mm levels on 2nd day, 10 and 12 mm levels on 5th day and 10 mm levels on 8th day seems to be nearly as good and operationally useful.

A BCG Vaccination induration size of 14 mm and above between 5th and 6th day of vaccination, for all practical purposes may be considered satisfactory for demarcating persons infected with M.tuberculosis from those non-infected. It can be concluded that estimation of prevalence of infection, when BCG vaccination is given to all without prior tuberculin testing, can be made on the basis of BCG vaccination induration size of 14 mm or more.

The article deals with primary complex and BCG vaccination. Lodgement or implantation of tubercle bacilli, at any site, in the body of an animal or human being is called primary infection. The tissue response by accumulation of polymorphonuclear leucocytes at the site of primary infection is termed as primary focus. The tubercle bacilli are transported from the primary focus to the lymph node through lymphatics. The primary focus, the lymphangitis and regional lymphadenitis together constitute primary complex. In 95% of cases it occurs in the lung: the initial polymorphic leucocytic reaction in the primary focus and the lymph nodes are soon augmented by large monocytes then epitheloid cells and the Langhans' giant cells. In about 2-4 weeks the reticuloendothehal system develops cell mediated immunity and tuberculo hypersensitivity. Most of the primary complexes (lesions) become innocuous after a short time harbouring the tubercle bacilli with arrested activity, but live and potentially virulent. There is always a lurking danger of these bacilli flaring up in the future to progressive tuberculous disease. BCG vaccination is aimed at establishing a controlled primary complex by intradermal injection of attenuated (harmless) live, bovine strain of tubercle bacilli in an attempt to forestall the infection with virulent tubercle bacilli among the uninfected persons. At the site of vaccination, the lower half of the left deltoid region, a primary focus is created from where some bacilli are transported to axillary lymph node through the lymphatics and complete the formation of primary complex. In 2-4 weeks time cell mediated immunity and delayed hypersensitivity are initiated and is completed in about 6-8 weeks time and the vaccinated persons show positive reaction to tuberculin test. The BCG lesion heals in 4-6 weeks time.

The advantages of primary complex established with BCG vaccination prior to a chance of natural infection are: i) primary tuberculosis disease caused by it can be ruled out; ii) there is no chance of spread of disease to adjoining parts i.e., haematogenous dissemination of disease leading to milliary, meningeal, bone tuberculosis etc., is prevented; iii) also the danger of future local flare up and thereby chances of disease after infection are reduced. To obtain maximum advantage from the BCG vaccination, it should be given at the earliest possible time in life of an individual.