A possible role for longitudinal data would be to validate some of the underlying assumptions about the steady state and ‘no efficacy for duration’. In particular, if there is need to disentangle the effects on acquisition and duration, longitudinal data are needed. Optimal study designs for the estimation of acquisition and clearance rates from repeated measurement of colonisation have been considered by Mehtälä et al. [18]. Finally,

a baseline study is useful in establishing see more the baseline prevalence and serotype distribution of pneumococcal colonisation, even when frequent longitudinal sampling is not feasible. The information about the frequency of colonisation by serotypes included in the current PCV can be used to interpret results from head-to-head trials. This study was supported as a part of the research of the PneumoCarr Consortium funded by a grant (37875) from the Bill and Melinda Gates Foundation through the Grand Challenges in Global Health Initiative. “
“Between 1998 and 2001 the World Health Organization (WHO1) convened the Pneumococcal Carriage Working Group. This group was charged with formulating a set of core methods for conducting studies of pneumococcal nasopharyngeal (NP) colonization primarily in the context of pneumococcal conjugate vaccine (PCV) efficacy

trials [1]. The PCV efficacy trials led to PCV licensure and now widespread inclusion of PCV in routine immunization programs around the world. Numerous MYO10 studies of PCV effect on NP colonization were published in the pre-licensure period and were available for consideration by regulators, although no indication was sought for this outcome. Selleckchem Protease Inhibitor Library PCV impact studies have also included carriage components, thereby providing important lessons about the performance and impact of PCV on a population level [2], [3] and [4]. Carriage studies have provided the key biological link to the indirect effect of

PCV on pneumococcal disease [2], shown that there is no change in the invasiveness of pneumococcal strains since PCV implementation [2] and [3], anticipated the impact of PCV on cross-reacting serotypes [2], [5] and [6], contributed to the identification of new pneumococcal serotypes [7] and [8], and have been central to our understanding of antimicrobial resistance evolution and impact [9] and [10]. The variability in results from pneumococcal carriage studies across diverse epidemiologic settings can be understood to derive from biologic effects rather than methodological differences, in large part because many of the standard pneumococcal carriage methods have been widely adopted. In the decade since last convening the working group there have been many key accomplishments including sequencing of 90 pneumococcal capsular loci [11], the advent of molecular detection and quantification of pneumococci in NP specimens and serotype-specific detection including improved detection of multiple serotype colonization.