1. *
LABORATORY-BASED SURVEILLANCE OF S. PNEUMONIAE INVASIVE DISEASE (IPD) IN CHILDREN: SEROTYPE DISTRIBUTION AND ESTIMATION OF VACCINES COVERAGE
B. V. M. Negrini1; M. I. C. Medeiros2 ; M. C. Brandileone2; S. C. G. Almeida2; D. C. Aragon 3 ; M. M. Mussi-Pinhata 3
1. Pediatrics, São Carlos Federal University- São Carlos SP-Brazil; 2. National Reference Centre for Meningitis and Pneumococcal Infections, Bacteriology Branch, Adolfo Lutz Institut, São Paulo-SP, Brazil; 3. Pediatrics, University of São Paulo, Ribeirão Preto, SP, Brazil
BACKGROUND
RESULTS
Streptococcus pneumoniae is the leading cause of respiratory infections and bacterial meningitis after the neonatal period. IPDs are preventable through vaccination. Currently available vaccines contain capsular polysaccharides of 23, 7, 10 and 13 serotypes.
The most commonly observed serotypes were:
14 (36.8%); 1 (13.5%); 6A (8.2%); 19A (5.3%); 9V (4.5%) and 23F (4.5%).
There were only three cases caused by sorotype 3 (2,2%). %
Deaths due to Pneumonia and other causes in children < 5 years
WHO, 2008.
Laboratory-based surveillance is the best way to know the distribution of pneumococcal sorotypes, although only a small part of the diseases caused by them are detectable by growth in bacterial culture. .
Only 3%-8% detectable in bacterial culture
Table 1. Observed and estimated percentage of serotypes covered by each vaccine
There is variation in the prevalence of pneumococcal serotypes depending on the geographic location, and the time period studied in the same geographical point.
There is also variation depending on the clinical disease type and age.
Observed (%)
Estimated (%) 7V
10V
13V
<24 months
55,7
64,6
84,8
55,2
65,2
83,9
> 24 months
48,2
83,3
90,7
48,6
82,0
90,0
Meningitis
33,3
44,4
81,5
36,3
49,3
82,9
Others
57,6
79,3
88,7
56,6
77,3
87,0
Temporal trends in the distribution of pneumococcal serotypes isolated from IPDs in Spain (Black, S. 2006)
Table2. Comparisons of the proportions of potential vaccine coverage, for each vaccine and their credibility intervals
OBJECTIVES
Comparison
Estimated
Difference (%)
ICr95%
Age
10V-7V
10,0
(-4,8; 24,5)
< 24
13V-7V
28,7
(15,5; 41,5)
 months
13V-10V
18,7
(6,0; 31,3)
33,4
(17,0; 49,2)
> 24
41,3
(26,2; 56,0)
7,9
(-4,0; 20,3)
Meningitis
20,7
(8,7; 32,6) No
30,4
(19,3; 41,03)
9,7
(-0,1; 19,6)
13,0
(-11,9; 36,8)
Yes
46,6
(24,4; 66,9)
33,7
(10,9; 55,0)
To estimate the proportion of pneumococcal serotypes coverage by conjugate vaccines for the prevention of IPDs among children according to age and disease type to assess the likely impact of their use in our region.
SUBJECTS AND METHODS
Between 1998 and 2005, 133 pneumococcal isolates obtained from 164 < 5 years old children who had IPDs were serotyped.
A total of 103 (77.4%) children had pneumonia, 27 (20.3%) had meningitis and 3 (2.3%) had other forms of disease.
The proportion of the 7, 10 and 13-valent conjugate vaccines coverage were calculated for meningitis and other forms of disease according to children’s age.
CONCLUSIONS
As compared to the 10-valent, 13-valent conjugate vaccine would allow larger coverage for IPD occurring in infants < 2 years and for those with meningitis.
For infants > 24 months of age, and children with disease outside of the Central Nervous System, the 10-valent and 13-valent conjugate vaccines permit similar coverage.
It is likely that 10-valent and 7-valent vaccines coverage for young infants and those with meningitis are equivalent.
Continuous monitoring of serotype changes is warranted.
Data analysis - To estimate the comparisons of the proportions of interest and their credibility intervals (95%Cr I) was set a binomial model with a logit link function and a random effect (to include the dependence of the proportions) under the Bayesian approach.
The software used was OpenBugs, version 3.2.1