The effect of abbreviated administration of a 7-valent pneumococcal conjugate vaccine on nasopharyngeal carriage S. pneumoniae in children
The use of 2 and 3 doses of a 7-valent pneumococcal conjugate vaccine in children 2, 4 and 11 months of age results in a significant decrease in the carriage of vaccine pneumococcal serotypes during the second year of life.
To date, the effect of abbreviated administration of the 7-valent pneumococcal conjugate vaccine (7-PCV) on nasopharyngeal carriage S. pneumoniae has not been fully studied in children , although this fact is very important in terms of subsequent collective effects (i.e. the spread of the beneficial effect of vaccinated children on unvaccinated children).
Employees of the Department of Pediatric Immunology and Infectious Diseases at the University Medical Center in Utrecht (Netherlands) conducted a randomized controlled trial to assess the effect of two patterns of use of the conjugate vaccine against pneumococcus 7-valent (2 doses vs 2 + 1 dose) for the nasopharyngeal carriage of pneumococci in young children compared to the control group.
This study was carried out in a cohort of 1,003 healthy newborns in the general population of the Netherlands from July 2005 to February 2008. The follow-up period continued until the children reached l age of 2 years.
The children participating in the study were randomly divided into three groups: the first received 2 doses of pneumococcal vaccine at the ages of 2 and 4 months; the second group, the vaccine was administered according to the 2 + 1 scheme at the ages of 2.4 and 11 months, the third group was the control (the vaccine was not used). The main endpoint of this study was to determine the frequency of carriage of pneumococcal vaccine serotypes in children during the second year of life.
At 12 months of age, the carriage of pneumococcal vaccine serotypes was significantly lower after using the two 7-PCV vaccination schedules with a carrier frequency of 25% (95% confidence interval 20-30%) and 20% (95% CI 16-25%) when using 2 doses and 2 + 1 regimens, respectively, compared to the carrier frequency of 38% (95% CI 33-44%) in the control group (both p values are less than 0.001). At the age of 18 months in the group of patients vaccinated according to the 2 + 1 scheme, the carrier of pneumococcal vaccine serotypes decreased further to 16% (95% CI 12-20%, p less than 0.001), and 24 months at 14% (95% CI 11 -18%, p less than 0.001). In the group of patients who received 7-PCV twice, the frequency of pneumococcal vaccine serotype carriers remained unchanged at 18 months of age (24%, 95% CI 20-29%, p less than 0.001 ), but decreased to 15% at 24 months (95% CI 11-19%, p less than 0.001). In the control group, the indicator studied remained stable (36-38%) until the children reached the age of 2 years.
Thus, compared to the absence of vaccination, the use of 2 and 3 doses of 7-PCV leads to a significant reduction in the carrying of vaccine serotypes of pneumococci during the second year of life.