F2 and pertussis: Healy and colleagues assessed serum IgG antibody levels against pertussis virulence factors pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN), and fimbriae (FIM) and recorded half-lives of 29.4 days for PT, 29.8 days for FHA, 31.2 days for PRN, and 35.8 days for FIM.