 A comparison of estimated IFRs with observed CFRs indicates that a substantial fraction of the time-dependent variability in observed mortality can be explained by the evolving age distribution of infections.
<clarity>  A comparison of estimated IFRs with observed CFRs indicates that a substantial fraction of the time-dependent variability in observed mortality can be explained by the evolving age distribution of infections.
 A comparison of effective IFRs with observed CFRs indicates that a substantial fraction of the time-dependent variability in observed mortality can be explained by the evolving age distribution of infections.