What time of year is Pertussis the worst?

[HRJ]

I am reading on here that it is summer. But all the news stations say fall/winter. Is there a book on this? Any published info?

[Otto]

It's usually quoted in the U.S. as being late summer/early fall (e.g., here, Fig. 4), but the distribution can be double-peaked (here). The intrayear oscillations (as opposed to the large interyear oscillation) don't seem to be particularly well understood--compare the relatively well behaved two-year periodicities in RSV with the noisy-looking pertussis curve in these Finnish data (PDF; Figs. 1-2).

[amnesiac]

Moving to H&H.