Nasopharyngeal (NP) colonization of S. pneumoniae in infants is generally acquired at approximately 4-6 months of age. Although there are differences in the prevalence and rank order of serotypes obtained from NP specimens and from those with invasive diseases, pneumococcal nasopharyngeal isolates may reflect the strains circulating in the community and may be used as a marker to predict serotype prevalence of invasive disease and resistance patterns. The information about pneumococcal strains found in Jordanian children and NP-carriage of infants is limited and do not include children living in rural regions. Monitoring serotype distribution is essential for the appropriate application of vaccination. Vaccine use in infants proves to be highly efficacious in the prevention of invasive pneumococcal disease as well as in decreasing the carriage of vaccine serotypes in the nasopharynx of infants which impacted significantly in the long run on otitis media infection and helped decrease the infection rates among contacts of these infants. The result has been a decrease in the pneumococcal infection rate among elderly contacts of these infants and decrease colonization with pneumococci. In order to determine the pneumococcal serotypes which are prevalent among infants attending day care centers (DCCs) in Jordan, a study of these types circulating among infants will be determined over a period of 15 months in 250-300 children attending the DCCs in Ajlun-City by taking 3 NP-swabs, the first before the first vaccine injection in May 2009, the second before the third injection at 10 months of age and the third swab sample is taken at 1 year of age (2-3 months after the last injection with the 7vPCV. The aims of this study were to determine the frequency of NP-carriage and serotype distribution of the strains isolated from infants less than 2 years old, and to get an insight about the coverage of the available and future pneumococcal conjugate vaccines developed for this infectious agent. Good results of this study project would make recommendations for the Ministry of Health (MOH) to include the vaccine in the National Vaccination Program. 15000 doses of the 7v PCV (Prevenar) were donated from Wyeth Pharmaceutical company to the MOH of Jordan in September 2008. These will be vaccinated in a vaccine program (for free) over 15 months period in 2009-2010 in one city in north Jordan called Ajlun. This city has 3676 births per year (Statistics of the MOH 2007). The vaccination program will start from the 18th of May, 2009, and ending in August 2010. The way the vaccine will be given is 2 + 1 injections as recommended by the vaccination committee of the MOH.