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Анагаахын Шинжлэх Ухааны Үндэсний Их Сургууль

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Changes in Pneumococcal Carriage in Hospitalised Children 2-59 Months of Age in Mongolia Following Pneumococcal Conjugate Vaccine Introduction
(Elsevier BV, 2023)
von Mollendorf, Claire
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Mungun, Tuya
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Ulziibayar, Munkhchuluun
;
Nguyen, Cattram D.
;
Batsaikhan, Purevsuren
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Impact of pneumococcal conjugate vaccine 13 introduction on severe lower respiratory tract infections associated with respiratory syncytial virus or influenza virus in hospitalized children in Ulaanbaatar, Mongolia
(2024-06)
Do, Lien Anh Ha
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Tsedenbal, Naranzul
;
Khishigmunkh, Chimidregzen
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Tserendulam, Bazarkhuu
;
Altanbumba, Lkhagvadorj
OBJECTIVES: Limited data indicate a beneficial effect of pneumococcal conjugate vaccines (PCVs) on respiratory syncytial virus (RSV) and influenza infections in young children. We evaluated the impact of 13-valent PCV (PCV13) introduction on the incidence of severe lower respiratory tract infections (LRTIs) associated with RSV or influenza in hospitalized children. METHODS: Our study was restricted to children aged <2 years with arterial oxygen saturation <93% and children with radiologically confirmed pneumonia nested in a pneumonia surveillance project in four districts of Ulaanbaatar city, Mongolia. We tested nasopharyngeal swabs collected on admission for RSV and influenza using quantitative reverse transcription-polymerase chain reaction. The impact of PCV13 on the incidence of LRTI outcomes associated with RSV or with influenza for the period April 2015-March 2020 was estimated. Incidence rate ratios comparing pre- and post-vaccine periods were estimated for each outcome for each district using negative binomial models and for all districts combined with a mixed-effects negative binomial model. Adjusted models accounted for seasonality. Sensitivity analyses were conducted to assess the robustness of our findings. RESULTS: Among 5577 tested cases, the adjusted incidence rate ratios showed a trend toward a reduction in RSV-associated outcomes: all LRTIs (0.77, 95% confidence interval [CI] 0.44-1.36), severe LRTIs (0.88, 95% CI 0.48-1.62), very severe LRTIs (0.76, 95% CI 0.42-1.38), and radiologically confirmed pneumonia (0.66, 95% CI 0.32-1.38) but inconsistent trends in outcomes associated with influenza. CONCLUSIONS: No significant reductions were observed in any outcomes associated with RSV and influenza after PCV introduction.
Scopus© Citations 1
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Effect of pneumococcal conjugate vaccine six years post-introduction on pneumococcal carriage in Ulaanbaatar, Mongolia
(2024-08)
von Mollendorf, Claire
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Mungun, Tuya
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Ulziibayar, Munkhchuluun
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Skoko, Paige
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Boelsen, Laura
Limited data from Asia are available on long-term effects of pneumococcal conjugate vaccine introduction on pneumococcal carriage. Here we assess the impact of 13-valent pneumococcal conjugate vaccine (PCV13) introduction on nasopharyngeal pneumococcal carriage prevalence, density and antimicrobial resistance. Cross-sectional carriage surveys were conducted pre-PCV13 (2015) and post-PCV13 introduction (2017 and 2022). Pneumococci were detected and quantified by real-time PCR from nasopharyngeal swabs. DNA microarray was used for molecular serotyping and to infer genetic lineage (Global Pneumococcal Sequence Cluster). The study included 1461 infants (5-8 weeks old) and 1489 toddlers (12-23 months old) enrolled from family health clinics. We show a reduction in PCV13 serotype carriage (with non-PCV13 serotype replacement) and a reduction in the proportion of samples containing resistance genes in toddlers six years post-PCV13 introduction. We observed an increase in pneumococcal nasopharyngeal density. Serotype 15 A, the most prevalent non-vaccine-serotype in 2022, was comprised predominantly of GPSC904;9. Reductions in PCV13 serotype carriage will likely result in pneumococcal disease reduction. It is important for ongoing surveillance to monitor serotype changes to potentially inform new vaccine development.
Scopus© Citations 10
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Effect of pneumococcal conjugate vaccination on pneumococcal carriage in hospitalised children aged 2-59 months in Mongolia: an active pneumonia surveillance programme
(2024-12)
von Mollendorf, Claire
;
Mungun, Tuya
;
Ulziibayar, Munkhchuluun
;
Nguyen, Cattram D
;
Batsaikhan, Purevsuren
BACKGROUND: Data on changes in pneumococcal serotypes in hospitalised children following the introduction of the pneumococcal conjugate vaccine (PCV) in low-income and middle-income countries are scarce. In 2016, Mongolia introduced the 13-valent PCV (PCV13) into the national immunisation programme. We aimed to describe the trend and impact of PCV13 introduction on pneumococcal carriage in hospitalised children aged 2-59 months with pneumonia in Mongolia over a 6-year period. METHODS: In this active surveillance programme, children aged 2-59 months with pneumonia who met the study case definition (cough or difficulty breathing with either respiratory rate ≥50 beats per min, oxygen saturation <90%, or clinical diagnosis of severe pneumonia) were enrolled between April 1, 2015, and June 30, 2021, from four districts in Ulaanbaatar. We tested nasopharyngeal samples collected at enrolment for pneumococci using lytA real-time quantitative PCR and conducted molecular serotyping and detection of antimicrobial resistance (AMR) genes with DNA microarray. We used log-binomial regression to estimate prevalence ratios (PRs) of pneumococcal carriage, comparing prevalence in the periods before and after the introduction of PCV13 and between vaccinated and unvaccinated children for three outcomes: overall, PCV13 vaccine-type, and non-PCV13 vaccine-type carriage. PRs were adjusted with covariates that were identified by use of a directed acyclic graph, informed by relevant literature. FINDINGS: A total of 17 688 children were enrolled, of whom 17 607 (99·5%) met the study case criteria. 6545 (42·5%) of 15 411 collected nasopharyngeal swabs were tested for pneumococci. In all age groups, a similar prevalence of pneumococcal carriage was shown between the pre-PCV13 period and post-PCV13 period (882 [48·0%] of 1837 vs 2174 [46·2%] of 4708; adjusted PR 0·98 [95% CI 0·92-1·04]; p=0·60). Overall, vaccine-type carriage reduced by 43·6% after the introduction of PCV13 (adjusted PR 0·56 [95% CI 0·51-0·62]; p<0·0001). Younger children (aged 2-23 months) showed a 47·7% reduction in vaccine-type carriage (95% CI 41·2-53·5; adjusted PR 0·52 [95% CI 0·46-0·59]; p<0·0001), whereas children aged 24-59 months had a 29·3% reduction (12·6-42·8; 0·71 [0·57-0·87]; p=0·0014). Prevalence of 6A, 6B, 14, 19F, and 23F decreased following the introduction of PCV13; however, 19F and 6A remained common (5·8% and 2·9%). Non-vaccine-type carriage increased (adjusted PR 1·49 [95% CI 1·32-1·67]), with 15A, NT2, and 15B/C being the most prevalent serotypes. Overall, 1761 (89·3%) of 1978 analysed samples contained at least one AMR gene. The percentage of samples with any AMR gene decreased with vaccine introduction (92·3% in the pre-PCV13 period vs 85·3% in the post-PCV13 period; adjusted odds ratio 0·49 [95% CI 0·34-0·70]), with similar decreases for samples with at least three AMR genes (46·8% vs 27·6%; 0·44 [0·36-0·55]). INTERPRETATION: 6 years after the introduction of PCV13 in Mongolia, the prevalence of vaccine-type carriage and AMR genes showed a reduction among young hospitalised children with pneumonia. Reductions in vaccine-type carriage are likely to result in reductions in pneumococcal pneumonia. FUNDING: GAVI, the Vaccine Alliance.
Scopus© Citations 14
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Respiratory Syncytial Virus and Influenza Infections in Children in Ulaanbaatar, Mongolia, 2015-2021
(2024-05)
Do, Lien Anh Ha
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Tsedenbal, Naranzul
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Khishigmunkh, Chimidregzen
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Tserendulam, Bazarkhuu
;
Altanbumba, Lkhagvadorj
BACKGROUND: Data available for RSV and influenza infections among children < 2 years in Mongolia are limited. We present data from four districts of Ulaanbaatar from April 2015 to June 2021. METHODS: This study was nested in an enhanced surveillance project evaluating pneumococcal conjugate vaccine (PCV13) impact on the incidence of hospitalized lower respiratory tract infections (LRTIs). Our study was restricted to children aged < 2 years with arterial O2 saturation < 93% and children with radiological pneumonia. Nasopharyngeal (NP) swabs collected at admission were tested for RSV and influenza using qRT-PCR. NP swabs of all patients with radiological pneumonia and of a subset of randomly selected NP swabs were tested for S. pneumoniae (S.p.) by qPCR and for serotypes by culture and DNA microarray. RESULTS: Among 5705 patients, 2113 (37.0%) and 386 (6.8%) had RSV and influenza infections, respectively. Children aged 2-6 months had a higher percentage of very severe RSV infection compared to those older than 6 months (42.2% versus 31.4%, p-value Fisher's exact = 0.001). S.p. carriage was detected in 1073/2281 (47.0%) patients. Among S.p. carriage cases, 363/1073 (33.8%) had S.p. and RSV codetection, and 82/1073 (7.6%) had S.p. and influenza codetection. S.p. codetection with RSV/influenza was not associated with more severe LRTIs, compared to only RSV/influenza cases. CONCLUSION: In Mongolia, RSV is an important pathogen causing more severe LRTI in children under 6 months of age. Codetection of RSV or influenza virus and S.p. was not associated with increased severity.
Scopus© Citations 5

Demberelsuren, Sodbayar

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