The normal reaction of BCG vaccine in newborns is due to the biological characteristics of BCG vaccine itself, which causes no systemic reaction after BCG vaccination, but only local reaction and local lymph node reaction, which are normal reactions of BCG vaccine. After BCG vaccination, small local mounds may appear, which disappear after half an hour, and the skin may be red and swollen after 2-3 days, with small red nodules appearing after 7-20 days. Local lymph node reactions can also occur, usually causing swelling of the ipsilateral lymph nodes, but the lymph nodes are relatively small, usually no more than 5 mm in diameter.