C5 and infection: Overall, no cause was reported for 67/112 BT-IVH events (59.8%); 43/112 BT-IVH events (38.4%) were owing to infection or other complement-amplifying conditions (e.g. surgery or pregnancy), and 2/112 BT-IVH events (1.8%) were reported to be associated with suboptimal inhibition of C5 (i.e. serum free C5 ≥ 0.5 μg/mL).