<qa>  What is the era of PCV use?There are four specific aims for this study: 1 to determine the overall and serotype specific prevalence and incidence of pneumococcal carriage among children and adults at high risk for carriage and disease in the era of routine pneumococcal conjugate vaccine PCV use compared with those measures in the same population prior to use of PCV vaccine; 2 to characterize the intrafamilial NP transmission of clones among those living with children less than 8 years of age; 3 to determine the immune correlates of protection from serotype specific pneumococcal carriage among individuals immunized and not immunized with PCV; and 4 to determine the relative invasiveness of serotypes of pneumococcus during an era of widespread PCV use and compare this to the relative invasiveness of serotypes prior to routine use of PCV. 