Figure 6. . . Comparison of number of pertussis notifications, proportion of vaccine coverage, and proportion of dominant multilocus sequence typing alleles and multilocus variable number tandem repeat analysis (MLVA) type 27 among a random selection of 661 isolates, United States, 1935–2009. Bars indicate case notifications; lines indicate 2-point moving average distributions of frequency for the time periods assigned in this study. Vaccine coverage data were collected for the United States Immunization Survey (USIS, 1962–1985), National Health Interview Survey (NHIS, 1991−1993), and National Immunization Survey (NIS, 1994−2009). No data are available for 1986−1990 because USIS was cancelled (15). The fim3B trend line was temporally and significantly associated with the rate of increase for pertussis notifications.