BCG Vaccination Programme Research Articles

The impact of changing BCG coverage on tuberculosis incidence in Swedish-born children between 1969 and 1989

In April 1975, the mass vaccination of newborns against tuberculosis was replaced by selective vaccination of groups at risk. BCG coverage fell from more than 95% before 1974 to 1.8% between 1975 and 1982 and thereafter reached an average of 13.7% up to 1989. The cumulative incidence of tuberculosis before 5 years of age was estimated among children born in Sweden during periods of high, low and moderate increasing BCG coverage. The incidence figures per 100 000 children was 0.8, 3.9 and 2.9, respectively, for children born to Swedish parents and 2.6, 39.4 and 13.2, respectively, for those born to foreign parents. The observed incidence of tuberculosis among non-BCG vaccinated children born to Swedish parents was within the expected limits given by a prognostic model based on the natural change of the risk of infection. The effectiveness of the selective BCG vaccination programme, which was intensified after 1981 for the second generation of immigrants, was estimated to 0.82 (95% confidence interval 0.38, 0.95) assuming that there was no change of the risk of infection for children born to foreign parents over the period studied. From April 1975 to December 1989, tuberculosis was notified in 85 children born in Sweden during the same period, 7 of them were BCG vaccinated and 78 non-vaccinated, 45 were symptomatic, 3 of them with disseminated tuberculosis.

A contact study to evaluate the BCG vaccination programme in Seoul

A contact study was undertaken in Seoul to determine the protective effect of the BCG programme in children up to 5 years of age. There were 1993 contact children to 4484 smear-positive patients with pulmonary tuberculosis. 1223 completed the examination, 806 had evidence of BCG vaccination, 417 had not. In total, 129 or 126 children were considered cases of tuberculosis according to radiological/clinical classification or scoring system, respectively. For the unvaccinated the respective numbers of cases were 84 and 80 and for the vaccinated 45 and 46. The data were stratified for factors that could have distorted comparability: age and sex, relationship of index case, feeding habits, room occupancy, treatment history of index case and health centre that diagnosed the index case. Only age was found to have a small effect. Correcting for this, the observed level of protection was 74% with 95% confidence limits of 62% and 82%. It appeared to be the same for all types of disease observed.

Case-control study on evaluation of BCG vaccination of newborn in Rangoon, Burma

A case-control study was carried out on 311 tuberculous children under 5 years of age and 1536 non-tuberculous controls, matched for age, sex and the sector of residence, to evaluate the effectiveness of BCG vaccination of newborns in Rangoon, Burma. BCG vaccination status of both the cases and their matched controls was recorded. BCG vaccination in the newborn conferred 38% protection against the sum total of all forms of tuberculosis. The protective efficacy varied with the different forms of tuberculosis. It was only 20% for primary complex and 52% and 80% for tuberculous meningitis and disseminated tuberculosis, respectively. The protective effect of BCG vaccination was highest during the first 3 years after vaccination and then waned during the subsequent years. Although the protective efficacy seemed to be low, the impact of a BCG vaccination programme on the preventable deaths, neurological sequelae and the health services expenses is considerable.

PROTECTIVE EFFICACY OF BCG AGAINST LEPROSY IN NORTHERN MALAWI

The effectiveness of a BCG vaccination programme in protecting against leprosy was assessed by case-control and cohort analyses of data from the Lepra Evaluation Project in Karonga District, Northern Malawi. Results indicate that BCG provides at least 50% protection against leprosy in this population and that protection is independent of age, sex, schooling status, or location within the project area. Agreement between these findings and those from a controlled trial in Uganda indicates that BCG is sufficiently effective against leprosy in East and Central Africa to be considered an important element of leprosy control in that region.

Benefits and costs of the schools' BCG vaccination programme.

By the mid-1980s the schools' BCG vaccination programme will be uneconomic. It is estimated that it will cost about pounds5500 to prevent one case of tuberculosis, the average total cost of which would be between pounds400 and pounds1300 depending on medical policy about the degree of illness for which hospital admission is necessary. In December 1975 the costs of the BCG programme were greater than its monetary benefits, probably by a factor of about 2.

Impact of BCG vaccination programmes in children and young adults on the tuberculosis problem

There is general agreement that BCG vaccination with a potent strain, when given to previously uninfected subjects, is highly effective in preventing the development of tuberculosis among them. This ‘direct’ effect may be measured in practice in terms of the proportion of cases prevented in the age-groups in which the vaccination has been made. It is also claimed that mass BCG vaccination — especially at school-leaving age — can be expected to yield benefits not only directly, but also indirectly, by breaking the chain of transmission and so preventing the development of tuberculosis in unvaccinated subjects. This ‘indirect’ effect may be measured, by analogy, in terms of the reduction in the numbers of cases in the age groups in which no vaccinations have been performed (the older age groups, and also young children, if BCG vaccination is given, for instance, to school-leavers). The indirect effect will be observed in terms of changes in both smear-positive and smear-negative cases. However, because smear-positive cases are the principal sources of infection, it is more meaningful to measure the indirect effect in terms of the reduction in the numbers of smear-positive (infectious) cases. The present paper falls into three parts: 1. I. A comparison of the trends in the incidence of infectious tuberculosis in Norway, Denmark and The Netherlands. The study confirms that the substantial direct effect of BCG vaccination on the total tuberculosis incidence, which was shown by Bjartveit and Waaler, also applies to the incidence of infectious tuberculosis. 2. II. A comparison of the trends in the incidence of infectious tuberculosis in the three countries and in different age groups over 30, and in the incidence of all forms of tuberculosis in children, in whom BCG vaccination has not been used. These comparisons suggest that the indirect effect of BCG on infectious cases of tuberculosis in persons aged 30 years and over, and on all forms of tuberculosis in children, in whom BCG vaccination has not been used, is not readily detectable, and so may not be large. However, the trends in tuberculosis incidence measure the total effects of all the policies for control used in the three countries under study. The comparisons between the three countries can therefore not isolate the ‘pure’ direct and indirect effects of BCG from the effects of other differences between the control policies. For this reason a theoretical study of the problem has been made. 3. III. A theoretical examination of the maximum likely indirect effect of a mass BCG vaccination policy in diminishing the prevalence of sources of infection in the population. This shows that the effect of BCG in preventing smear-positive cases in developing countries (if a constant risk of infection of about 3 per cent is presumed), is between 0.3 per cent and 2.0 per cent per year. This effect depends mainly upon the efficacy of BCG vaccine, the population covered and the duration of protection from BCG vaccination. Thus it seems that BCG vaccination, even if used in a mass-campaign at ages 15–30 years, will not substantially influence the chain of transmission, especially if the risk of tuberculosis infection is high and has not been decreasing. However, it has to be stressed that mass BCG vaccination was introduced for its direct effect and it should be applied whenever it is justified.

The impact of the BCG vaccination program in Hungary on the tuberculosis problem in children.

Using the yearly standard data supply and data of some representative epidemiological investigations, the present authors studied the impact of the BCG vaccination program on tuberculosis in children during the last 20 years in Hungary. Considering the incidence of active tuberculosis among vaccinated and unvaccinated children according to age as well as the rate of vaccination in the various age groups, authors point out that: [1] the BCG vaccination program proved to be effective during the entire period of investigation; [2] prevalence of bacillary TB had a marked influence on the incidence of the disease, both in vaccinated and unvaccinated children; [3] the impact of the BCG-vaccination program on the problem of childhood tuberculosis had been determined by the percentage of those vaccinated; and finally [4] the relatively high frequency of disease in the higher age groups (15 to 19-year-olds) indicates that the TB problem still exists and continuation of the various TB control methods is therefore justified.

The prevalence of tuberculin sensitivity and its relation to a BCG vaccination program among Chinese in Hong Kong.

The prevalence of tuberculin sensitivity and its relation to a BCG vaccination program among Chinese in Hong Kong.

Research Contributions of BCG Vaccination Programs: I. Tuberculin Allergy as a Family Trait

Research Contributions of BCG Vaccination Programs: I. Tuberculin Allergy as a Family Trait

TRENDS

IN THE "Economic Cooperation Act of 1950," Congress has included an authorization of $15,000,000 with broad authority to the President to make contributions to the United Nations for international children's needs in the fields of health and welfare. Congress indicated that it expects the President "to use his authority prudently with a view to actual needs and to the desirability of the earliest practicable transfer of the international childen's welfare programs concerned from the present temporary agency to a permanent arrangement within the United Nations framework." Thus Congress has taken an important step to assure continuation of the work of the United Nations International Children's Emergency Fund (UNICEF) which is so essential to millions of the world's children. This Fund, cooperating with foreign countries, has been most effective in helping to supply milk or a daily supplementary meal to many millions of children and pregnant mothers. In cooperation with the U. N. World Health Organization, the Fund has undertaken with the Danish Red Cross and its Scandinavian associates a mass antituberculosis BCG vaccination program for European children. This campaign is unprecedented in the international public health field and should eventually yield results not only in the reduction of tuberculosis on a vast scale, but also in adding greatly to our knowledge of BCG vaccination.