To evaluate the norovirus component of the Vergene II gastrointestinal diagnostic assay platform.

To provide a case-control study comparing naturally occurring group B strep antibodies in young infants with invasive disease versus controls will establish antibody thresholds associated with protection and inform decisions about future maternal Group B Streptococcus vaccine licensure.

To evaluate the impact of Pneumococcal Conjugate Vaccine (PCV-13) on vaccine and non-vaccine serotypes causing both invasive and non-invasive diseases in Qatar. The study also assesses the overall prevalence and serotype distribution of S.pneumoniae nasopharyngeal carriage in both healthy and sick children below five years of age over a three-year period.