Timing and dose of BCG vaccination in infants as assessed by postvaccination tuberculin sensitivity

Abstract

Tuberculosis is an important public health problem in developing countries and BCG plays an important role in preventing serious form of the disease in children. BCG induced tuberculin sensitivity is a quantitative characteristic and has been used to compare vaccine efficacy. The standard dose of BCG vaccine is 0.1mg in 1 ml though manufacturers of certain strains of BCG, i.e., Copenhagen 1331 recommend half dose in infants. There are also varying ideas about the optimum time to vaccinate babies and some studies suggest that late vaccination confers a high degree of protection. This study was carried out to evaluate tuberculin sensitivity and side effects following 0.05 ml and 0.1 ml of BCG at birth and 0.1 ml of BCG at 4-6 weeks of age. Two hundred and thirty eight newborns were vaccinated randomly with 0.05 ml and 0.05 ml and 0.1 ml of BCG vaccine (Copenhagen 1331 strain) containing .69 million culturable particles per ml. One hundred and eight infants 4-6 weeks of age were vaccinated with 0.1 ml of BCG. One hundred and fifty five (44.7%) infants were evaluated by Mantoux test using 1TU PPD RT23 10-12 weeks after vaccination and 105 (30.6%) followed up till 6 months for any side effects. No significant difference in mean tuberculin reaction, tuberculin positivity and mean scar size was observed in groups receiving 0.1 ml at birth or 4-6 weeks of age. However, the group receiving 0.05 ml at birth had a significantly lower mean tuberculin reaction, tuberculin positivity and mean scar size. No locoregional side effects were observed. Hence the present practice of giving 0.1 ml of BCG at birth should be continued.