For non-tuberculosis respiratory infections, there was evidence for statistically significant differences between all subgroups (test for subgroup differences: I2 = 77%; p < 0.0001), suggesting more pronounced BCG-mediated NSE in non-tuberculosis respiratory infections (1) in adolescents or adults, (2) in low-birth-weight children or morbid participants, (3) in trials conducted in Western Europe or Australia, (4) in trials with a follow-up period smaller or equal to six months, (5) and in trials collecting outcome data by medical diagnosis compared to participant-reported data. Here, ENO2 is linked to tuberculosis.