Even as health officials investigate the death of two children after they were administered Hepatitis B and DTP (diphtheria, tetanus and pertussis) vaccines, TOI has learnt of one more incident in which a two-month-old died this week, this time after taking the BCG (Bacille Calmette-Guerin) vaccine given to prevent childhood tuberculosis. While such deaths are known in the medical world as "adverse effect following immunisation'', three deaths in the span of a week is uncommon, said health officials. The yet-to-be-named infant, the son of Chembur Naka resident Geeta Mane, was administered the BCG vaccine at a health post in Abhudaya nagar on Tuesday.