Infection and disease within a birth cohort from Kilifi District, Kenya. Panels on the left show data for cohort children recruited in the first phase (Jan-May 2002), and on the right second phase recruits (Dec 2002 – July 2003). Panels a-b show, for each week and year of surveillance, numbers of children within the cohort (grey area), numbers of RSV cases (histogram), and cumulative number of primary (thin line) and repeat cases (thick line). Similarly, panels c-d show cases of LRTI (markers) and RSV-LRTI (bars), and panels e-f cases of severe-LRTI (light bars) and RSV severe-LRTI (dark bars). Limits for each RSV epidemic are as follows: epidemic 1 from weeks (inclusive) 11-26 year 2002, epidemic 2 weeks 49-52 2002 and weeks 1-15 2003, epidemic 3 weeks 2-22 2004, epidemic 4 weeks 46-52 2004 and weeks 1-7 2005.