15 were covered. The two NHBA 21 fHbp 1.15 strains not predicted to be covered were from Québec. This study provides the first data on the potential coverage of

Canadian MenB isolates by the investigational 4CMenB vaccine. Using a conservative predictor for coverage, 4CMenB appears to provide good strain coverage (65% for cc41/44 and 82% for cc269) for the most prevalent recent ccs, ABT-263 nmr which include ST-269 and ST-154 predicted covered at 95% and 100%, respectively. Across all age groups, the majority of isolates are predicted to be covered by the 4CMenB vaccine. Of note the vaccine appears to provide coverage across a wide diversity of endemic strains and is not limited to protecting against one or two subtypes. At least 40% of isolates were covered by two or more vaccine

antigens, with fHbp and NHBA contributing the most to vaccine coverage. The 4CMenB antigens are also found in non-MenB isolates thus protection against these other serogroups may be an added bonus, particularly in individuals not immunized with meningococcal conjugate see more vaccines. In terms of prevention, over two-thirds of the recent cases caused by MenB were potentially preventable with this vaccine. Our results are similar to those found in England and Wales where the overall proportion of strains estimated to be covered in 2007–2008 was 73% (57–87%) and the combinations of antigens with MATS RP above the PBT was similar to that observed in Canada [26]. The overall frequency of coverage by at least two antigens was lower (40% vs. 50%) in Canadian than in English and Welsh isolates [26], thus the chance for escape mutants to emerge with vaccine use could differ between the two countries. The last national

characterization of MenB isolates was from 1994 to 1996. In this earlier study the most commonly expressed PorA serosubtypes were P1.14 (13.3%), P1.16 (11.3%), P1.5 (7.9%), P1.7 (7.0%), P1.13 (7.0%), and P1.2 (4.3%); and the only hypervirulent clones were cc32 and cc11 [27]. The much most noticeable differences in our current study were the emergence of the ST-269 clone in Québec and a change in the prevalence of other hypervirulent clones. CC32 decreased from 12.0% in 1994–1996 to 5.1% in 2006–2009 and cc41/44 became a predominant clone, accounting for about 33% of MenB isolates in 2006–2009. Besides these temporal changes, we noted geographical differences in the distribution of common hypervirulent clones from 2006 to 2009 as exemplified by the finding of ST-269 (cc269) and ST-571 (cc41/44) mainly in the province of Québec, and ST-154 (cc41/44) from Ontario and the Atlantic provinces. By province, the predicted coverage of 4CMenB ranged from 43% to 100% and reflected the strains circulating within each region and the level of antigen expression within each isolate.