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UDC 614.446:616.24-002:616.157-053.4(571.15)
ASSESSMENT OF IMMUNIZATION AGAINST PNEUMOCOCCUS INFECTION OF CHILDREN UNDER 5 YEARS IN THE CITY OF BARNAUL OUTSIDE THE PREVENTIVE VACCINATION SCHEDULE
Altai State Medical University, Barnaul Yu.A. Kozyanova, T.V. Safyanova
In December 2016, in terms of a retrospective cohort epidemiological study, 2 cohorts of children (vaccinated and unvaccinated) were chosen, each consisting of 156 children under the age of 60 months, to assess the effectiveness of vaccination with a 10-valent conjugate vaccine (PCV) against pneumococcal infection on the number of episodes of Cases respiratory and ENT diseases, as well as on the number of antibiotic courses prescribed for the treatment of these diseases. The results of the study showed that the use of polyvalent conjugate pneumococcal vaccine reduced the frequency of episodes of Cases of respiratory and ENT diseases by 34.1% (95% CI: 31.1-37.0), and the frequency of prescriptions of antibacterial drugs for their therapy by 52.7% (95% CI: 43.7-61.6). Key words: S. pneumoniae, respiratory diseases, diseases of the respiratory tract, conjugated pneumococcal vaccines, courses of antibacterial therapy.
Introduction
Streptococcus pneumoniae is often a representative of the normal microflora of the upper respiratory tract [1]. According to the World Health Organization (WHO), pneumococcus occupies a leading position in the etiological structure of acute otitis media (AOM) and community-acquired pneumonia (CAP), especially in childhood [2, 3, 4, 5], which is a significant health problem in the whole world. Taking into account the existing antibiotic resistance of this microorganism [6, 7], vaccination, as one of the most effective preventive measures against this infection [5], is of particular relevance. In the Russian Federation, vaccination against pneumococcal infection was introduced in the National Vaccination Schedule in late 2014 [8]. In Altai Krai, the effectiveness of immunization has not been assessed, but there has been an experience with the use of vaccination against pneumococcal infection in an organized groups of children until 2014.
Research objective: to evaluate the epidemiolog-ical effectiveness of vaccination against pneumo-coccal infection outside the National Vaccination Schedule in relation to the number of cases of respiratory and ENT infections in children of Barnaul under the age of 5 years.
Materials and methods
In terms of a retrospective cohort epidemio-logical study, 2 groups of children born in 20122013 were chosen, each consisting of 156 children under the age of 60 months. One group included children vaccinated with 10-valent PCV according to the 2+0, 2+1 scheme before the start of mass immunization against pneumococcal infection, the other group - unvaccinated children of the same age (± 1-2 months), who were observed in the same
clinic (who had not received a single dose of vaccine against pneumococcal infection). The observation period was since the last dose of vaccination + 1 month to 60 months.
The study consisted of a passive component: an independent study of the medical records of children in the cohort. According to the form number 112/u "History of child development" in the studied groups, there were tracked the doctor registered episodes of Cases of the upper respiratory tract and respiratory organs and the appointment of courses of antibiotics in the treatment of these nosologies.
To calculate the vaccine efficacy (VE), the formula VE = 1- RR was used, where RR = relative rate (relative frequency) of courses of antibiotics or episodes of Cases.
The quartiles method was used to estimate the distribution and description of the data. By asymmetric distribution of the feature, the assessment of the reliability of differences in the analyzed groups was made by the criterion x2 (chi-square). In other cases, the arithmetic mean (X) and the standard error of the mean (± m) were calculated, followed by the Student's criterion assessment.
In all procedures of statistical analysis, the critical level of significance was assumed to be 0.05.
Results and discussion
According to the results of the study, it was found, that the average age of vaccination onset constituted 16.6±7.5 months, which differed from the recommended one - 2 months. Children vaccinated according to the 2+0 scheme were 141, according to the 2+1 - 15. The total follow-up duration (time of risk) for each cohort was 335.86 years (4030.3 months). On average, the duration of ob-
servation for each participant (time of risk) of both cohorts was 2.55±0.40 years (25.84 ± 4.76 months).
During the study period, the total number of episodes of the nosologies studied in a cohort of vaccinated children was 666, in a cohort of un-
vaccinated, 1011 episodes were recorded. The main proportion of vaccinated children was in the range from 0 to 4 times, unvaccinated - from 5 to 9 times (Table 1).
Table 1.
The proportion of vaccinated and unvaccinated children, depending on the number of episodes of Cases of the studied nosologies
Quartiles Unvaccinated, % Vaccinated, %
1 (0-4 episodes) 32,1 58,3
2 (5-9 episodes) 48,7 35,3
3 (10-14 episodes) 17,3 6,4
4 (15 and more episodes) 1,9 0,0
The maximum number of episodes during the observation period was recorded in an unvac-cinated child and amounted to 23 cases. A similar number among the vaccinated was 14.
Therefore, the frequency of episodes of the studied diseases among vaccinated children is less than among unvaccinated (p <0.05).
During the study period, 61 courses of antibacterial drugs were prescribed in a cohort of vacci-
nated children, 129 courses were given to a cohort of unvaccinated children. There was a large asymmetry in the frequency of prescription of antibiotics for the treatment of the studied diseases among vaccinated children: a greater proportion of children with a low frequency of prescription of courses of antibacterial drugs among those vaccinated compared with unvaccinated (Table 2).
Table 2.
The proportion of vaccinated and unvaccinated children, depending on the number of prescribed courses of antibacterial drugs for the treatment of the studied nosology
Quartiles Unvaccinated, % Vaccinated, %
1 (0-1 course) 78,2 94,2
2 (2-3 courses) 17,3 5,1
3 (4-5 courses) 3,2 0,6
4 (6 and more courses) 1,3 0,0
The effectiveness of vaccination of the given sample in relation to the reduction of prescribing courses of antibacterial drugs was 52.7% (95% CI: 43.7-61.6), in relation to the reduction of episodes of Cases of diseases studied - 34.1% (95% CI: 31.1 -37.0).
Conclusion
The results of the study showed that the use of conjugated pneumococcal vaccine reduced the incidence of respiratory organs and ENT organs in the cohort under study, as well as the frequency of prescribing antibacterial drugs during their treatment, which may be of significant importance in combating the development of antibiotic resistance.
References
1. Baranov A.A., Briko N.I., Namazova-Barano-va L.S., Ryapis L.A. Streptococci and pneumococci. M.: Feniks; 2013.
2. Kozlov R.S., Krechikova OI, Muravyov A.A. et al. The results of a study of the prevalence of community-acquired pneumonia and acute oti-16
tis media in children under 5 years of age (PAPI-RUS) in Russia. The role of S. pneumoniae and N. influenzae in the etiology of these diseases. Clinical Microbiology and Antimicrobial Chemotherapy. 2013; 15(4):246-260.
3. Safyanova T.V. Some features of the prevalence of community-acquired pneumonia and acute otitis media in Altai Krai. MediAl'. 2014; 3(13):78-80.
4. Kozyanova Yu.A., Safyanova T.V. Several epidemiological peculiarities of outhospital pneumonia in the Altai Territory. Medical Almanac. 2016; 3(43):108-111.
5. Pneumococcal conjugate vaccine for childhood immunization-WHO position paper. Wkly Epidemiol Rec. 2007; 82(12):93-104.
6. Kozlov R.S. The problem of antibiotic resistance in pediatrics. Russian Medical Journal. 2014;3:238.
7. Malyavina U.S., Goncharova M.G., Ovchin-nikov A.Yu. Antimicrobial therapy of acute purulent otitis media in pediatric practice: the feasibility of using cephalosporins. Consilium Medicum. 2007;1:30-32.
8. Order of the Ministry of Health of the Russian Federation No 125n of 21.03.2014. "On approval of the national calendar of vaccinations." Moscow; 2014.
Contacts
Corresponding author: Kozyanova Yulia Ana-tolyevna, post-graduate student of the Department of epidemiology, microbiology and virology of ASMU, Barnaul. 656056, Barnaul, ul. Papanintsev, 126.
Tel.: (3852) 566924.
E-mail: [email protected]
Author information
Safyanova Tatyana Viktorovna, Doctor of medical Sciences, Head of the Department of Epidemiology, Microbiology and Virology of the Altai State Medical University, Barnaul. 656056, Barnaul, ul. Papanintsev, 126. Tel.: (3852) 566924. E-mail: [email protected]
