Other findings in this study are also worthy of comment; in Philadelphia, the wintertime peak in pneumococcal incidence occurred about six weeks later than previously been described in U.S. adults [5] . In addition, a gradual increase in cases was observed during the 5-year study period. We suspect that this increase is less likely to represent a true surge in disease rates, which have actually been falling in the U.S. with the introduction of 7-valent conjugate pneumococcal vaccine [41] ; rather, we suspect that this increase, which is more attenuated after 2003, represents the gradual increase in reporting that commonly fol-lows implementation of new infectious disease reporting requirements [42] .