Introduction:

Nasopharyngeal colonization by pneumococci is defined as the initial moment when the bacterium lodges in the nasopharynx of the person.

Objective:

To estimate the proportion of risk factors associated with nasopharyngeal colonization by pneumococci in children vaccinated with conjugate pneumococcal vaccines (CPV).

Material and Methods:

One year after pneumococcal vaccination, a follow-up case-case-control study was conducted in children aged 1-5 years by means of a phase II/III controlled, randomized, double-blind clinical trial. The time horizon was from November 2015 to April 2016. The study included 50 % of the total of children vaccinated during the experimental study. The universe consisted of 1135 children who were vaccinated during the clinical trial. A simple random sampling that included 555 persons was applied. A survey was conducted and nasopharyngeal exudate samples were taken. Tables of frequencies were presented. Prevalence ratio was used as a measure of association. Also, 95 % confidence intervals were calculated for each proportion.

Results:

Being between the ages of 2-5 years acts as protective factor against nasopharyngeal colonization with respect to the young child. Living with persons older than 65 years is a significantly associated risk factor with nasopharyngeal colonization.

Conclusions:

The introduction of pneumococcal vaccines in pre-school children can have a significant impact on colonization burden and the transmission of pneumococcal diseases.

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