F2 and infection: In terms of recent infection/vaccination, the proportion of the population presenting anti-PT IgG levels compatible with recent contact to B. pertussis (anti-PT IgG levels in the range of 40–99 IU/ml) was 9.46% (95% CI 7.85–11.35%; 102/1078) with the lowest percentage found in the 6–11 months group at 3.07% (95% CI 1.49–6.20%; 7/228; p = 0.0009 vs. total, Table 2) regardless of location.