“…In the United States, current medical practice recommends that immunization begin at 2 months of age, or earlier in areas of high endemicity (22). Previous studies to assess the immune response to pertussis vaccines or B. pertussis infection have employed agglutination-type assays (1,2,8,12,13,16,27,30,40,41), complement fixation (7,23,24), bactericidal assays (3), and enzyme-linked immunosorbent assays (ELISA) (17,33,39). Since whole cells or disrupted whole cell preparations were used as antigens in these assays, it VOL.…”