In non-vaccinated individuals, and especially if proper treatment is delayed, death can occur in up to 10% of clinical cases despite antibiotics and the use of anti-sera, Diphtheria is transmitted mainly by direct projection (droplet spread).
Če se ustrezno zdravljenje ne začne pravočasno, lahko pri necepljenih posameznikih v do 10 % kliničnih primerov nastopi celo smrt kljub uporabi antibiotikov in antiserum. Davica se prenaša predvsem z neposrednim stikom (kapljično prenašanje).