[Pathogenic agents causing acute respiratory tract infections in pediatric patients in Spring, 2023, in Beijing].

Objective: To explore the pathogenic agents of acute respiratory infection (ARI) in children in Beijing. Methods: In the cross-sectional study, 3 groups of children from different departments were enrolled from Feb 6th, 2023 (6th week) to May 28th (21th week), 2023, including influenza-like case group from emergency department for nucleic acid testing of influenza virus (Flu) and human metapneumovirus (HMPV), the outpatient ARI group under nucleic acid testing for Flu, respiratory syncytial virus (RSV), adenovirus (ADV), and parainfluenza virus (PIV), and the inpatient ARI group under nucleic acid testing for Flu, RSV, HMPV, ADV, human bocavirus (HBoV), Rhinovirus (Rh), PIV, coronavirus (HCoV), Mycoplasma pneumoniae (Mp) and Chlamydia pneumonia (Cp). Results: There were 320 influenza-like cases enrolled, including 192 males and 128 females, aged 4.7 (3.6, 6.9) years, and 117 cases (36.6%) positive for Flu A, which contained similar proportion of pandemic H1N1 (H1N1) 47.0% (55/117) and H3N2 53.0% (62/117), and 13 cases for HMPV 4.1% (13/320). The rate of Flu reached its peak at the 10th week, with H1N1 as the predominant one from the 6th to 9th week (10.0%-50.0%) and then H3N2 from the 10th to 16th week (15.0%-90.0%). HMPV was detected from the 15th week 5.0% (1/20), and then reached to 30.0% (6/20) at the 20th week. In the outpatient ARI group, 7 573 were enrolled, including 4 131 males and 3 442 females, aged 4.0 (2.1, 5.3) years, and the highest positive rate for RSV 32.9% (2 491/7 573), followed by Flu A 12.1% (915/7 573). The dominant one was Flu A in weeks 6-14 (23.2%-74.7%), then RSV in the 15th week 24.8% (36/145). In the inpatient ARI group, 1 391 patients were enrolled, including 804 males and 587 females, aged 3.3 (0.4, 5.8) years, and the highest positive rate for Rh 18.7% (260/1 391), followed by RSV 12.4% (173/1 391), Flu A 10.2% (142/1 391, of which 116 cases (81.7%) were H1N1, and 26 cases (18.3%) were H3N2) and HMPV 3.1% (43/1 391). H1N1 was detected from the 7th week 10% (6/60), to peak in the 11th week 31.8% (21/66). H3N2 was detected from the 8th week 1.5% (1/68), and then kept in low level. The proportion of H1N1 among Flu was 81.7% (116/142) in the inpatient ARI group. RSV was detected from 12th week 1.3% (1/80), reaching 30.4% (35/115) at 19th week. The positive rate of HMPV reached 12.1% (14/116) at 21th week. Conclusions: In the spring of 2023, the first one in Beijing is the Flu epidemic, with H1N1 being the predominant one in the early stage and H3N2 in the later stage. Then, there is a postponed RSV epidemic and an increased HMPV detection. In addition, nucleic acid testing for outpatient children should be strengthened to provide early warning of epidemics.

[Analysis of common viral infection in surveillance cases of febrile respiratory syndrome in 9 provinces of China from 2009 to 2021].

Objective: To understand the common viral infection among the surveillance cases of fever respiratory syndrome (FRS) in nine provinces in China. Methods: The research data were obtained from nine provinces (Anhui, Beijing, Guangdong, Hebei, Hunan, Jilin, Shandong, Shaanxi and Xinjiang) in the "Infectious Disease Surveillance Technology Platform Information Management System" of the Chinese Center for Disease Control and Prevention from January 2009 to June 2021. Finally, 8 243 FRS cases with nucleic acid detection results of eight viruses [human influenza virus (HIFV), human respiratory syncytial virus (HRSV), human adenovirus (HAdV), human parainfluenza virus (HPIV), human rhinovirus (HRV), human metapneumovirus (HMPV), human coronavirus (HCoV) and human Boca virus (HBoV)] were included in the study. The χ2 test/Fisher exact probability method was used to analyze the difference of virus detection rate in different age groups, regions and seasons. Results The M (Q1, Q3) age of 8 243 FRS cases was 4 (1, 18) years old, and 56.56% (4 662 cases) were children under 5 years old. Males accounted for 58.1% (4 792 cases) of all cases. All cases were from outpatient/emergency department (2 043 cases) and inpatient department (6 200 cases). The virus detection rates of FRS cases from high to low were HRSV, HIFV, HPIV, HRV, HAdV, HMPV, HCoV and HBoV. Two or more viruses were detected simultaneously in 524 cases, accounting for 15.66% of virus-positive cases. The difference of the virus detection rate in different age groups was statistically significant (all P values<0.05), and the virus detection rate in children<5 years old was higher (49.96%). The positive rate of any virus in south China was higher than that in north China (P<0.001). The virus-positive FRS cases were detected throughout the year. The detection rate of HRSV was higher in autumn and winter. The detection rate of HIFV was higher in winter. The detection rate of HMPV was higher in winter and spring. The detection rates of HPIV, HRV, HCoV and HBoV were higher in summer and autumn, while there was no significant difference in the detection rate of HAdV in different seasons. Compared with 2009-2019, the detection rate of any virus in 2020-2021 decreased from 41.37% to 37.86%. The detection rate of HIFV decreased sharply from 10.62% to 1.37%. The detection rate of HPIV decreased from 8.24% to 5.88%. The detection rate of HRV and HBoV increased from 5.43% and 1.79% to 9.67% and 3.19%, respectively. Conclusion: HRSV and HIFV infections are more common among FRS cases in nine provinces in China from 2009 to 2021, and the epidemiological characteristics of eight common respiratory viruses vary in different age groups, regions and seasons.

[Clinical characteristics of human adenovirus infection in hospitalized children with acute respiratory infection in Beijing].

Objective: To compare the clinical characteristics of different types of human adenovirus (HAdV) infection in hospitalized children with acute respiratory infection in Beijing, and to clarify the clinical necessity of adenovirus typing. Methods: In a cross-sectional study, 9 022 respiratory tract specimens collected from hospitalized children with acute respiratory infection from November 2017 to October 2019 in Affiliated Children's Hospital, Capital Institute of Pediatrics were screened for HAdV by direct immunofluorescence (DFA) and (or) nucleic acid detection. Then the Penton base, Hexon and Fiber gene of HAdV were amplified from HAdV positive specimens to confirm their HAdV types by phylogenetic tree construction. Clinical data such as laboratory results and imaging data were analyzed for children with predominate type HAdV infection using t, U, or χ2 test. Results: There were 392 cases (4.34%) positive for HAdV among 9 022 specimens from hospitalized children with acute respiratory infection. Among those 205 cases who were successfully typed, 131 were male and 74 were female, age of 22.6 (6.7, 52.5) months,102 cases (49.76%) were positive for HAdV-3 and 86 cases (41.95%), HAdV-7, respectively, while 17 cases were confirmed as HAdV-1, 2, 4, 6, 14 or 21. In comparison of clinical characteristics between the predominate HAdV type 7 and 3 infection, significant differences were shown in proportions of children with wheezing (10 cases (11.63%) vs. 25 cases (24.51%)), white blood cell count >15 ×109/L (4 cases (4.65%) vs.14 cases (13.73%)), white blood cell count <5×109/L (26 cases (30.23%) vs.11 cases (10.78%)), procalcitonin level>0.5 mg/L (43 cases (50.00%) vs. 29 cases (28.43%)), multilobar infiltration (45 cases (52.33%) vs.38 cases (37.25%)), pleural effusion (23 cases (26.74%) vs. 10 cases (9.80%)), and severe adenovirus pneumonia (7 cases (8.14%) vs. 2 cases (1.96%)) with χ²=5.11, 4.44, 11.16, 9.19, 4.30, 9.25, 3.91 and P=0.024, 0.035, 0.001, 0.002, 0.038, 0.002, 0.048, respectively, and also in length of hospital stay (11 (8, 15) vs. 7 (5, 13) d, Z=3.73, P<0.001). Conclusions: HAdV-3 and 7 were the predominate types of HAdV infection in hospitalized children with acute respiratory tract infection in Beijing. Compared with HAdV-3 infection, HAdV-7 infection caused more obvious inflammatory reaction, more severe pulmonary symptoms, longer length of hospital stay, suggesting the clinical necessity of further typing of HAdVs.

[Clinical characteristics of children infected with different subtypes/genotypes of human respiratory syncytial virus in Beijing from 2009 to 2017].

Objective: To explore the different clinical characteristics of children infected with different subtype/genotype of human respiratory syncytial virus (HRSV) in Beijing. Methods: Respiratory specimens for positive HRSV were randomly collected from children with acute respiratory tract infection (ARTI) in the epidemic season of HRSV from November of each year to January of the next year during 2009 and 2017. G genes of HRSV were amplified and sequenced for subtyping and genotyping by bioinformatics analysis. Clinical data were collected and analyzed. Results: Out of 590 children, 376 (63.7%) with subtype A, and 214 (36.3) with subtype B. The annual dominant subtypes of HRSV from 2009 to 2017 were B-A-A-B-AB-A-A-B-A, respectively, whilst a total of 10 genotypes were detected with 95.8% assigned to genotype ON1 and NA1 of subtype A, and genotype BA9 of subtype B. Children infected with subtype B (96 cases, 44.9%) were more likely aged 0-3 month old than those with subtype A (118 cases, 31.4%) (P=0.001), and more likely to be admitted to Intensive Care Unit(ICU) ((124 cases, 57.9%) than those with subtype A (172 cases, 45.7%)) (P=0.005). Statistical significance were shown among children infected with genotype ON1, NA1 or BA9, in the possibility of infection in children aged 0-3 month (P=0.003), proportion of admission into ICU (P=0.007), length of stay in hospital (P=0.001), and clinical outcome (P=0.001), respectively. Conclusion: Children infected with different subtype or genotype of HRSV have different clinical characteristics, which stresses the important role of the monitoring HRSV subtypes and genotypes among children.

[Molecular epidemiology of norovirus associated with pediatric acute gastroenteritis in Beijing in 2020].

Objective: To investigate the molecular epidemiology of norovirus associated with pediatric acute gastroenteritis in Beijing under the Working Mechanism for Joint Prevention and Control of the Epidemic in 2020. Methods: This was a retrospective, repeated cross-sectional study. Fecal or vomit samples (1 213 cases) were collected from children visited the Capital Institute of Pediatrics Affiliated Children's Hospital for acute gastroenteritis from January 1 to December 31, 2020. First, real-time reverse PCR (RT-PCR) was used to screen the samples for norovirus, and then RdRp gene and capsid gene VP1 of norovirus-positive samples were amplified by conventional RT-PCR for genotyping based on the nucleotide sequence. The χ2 test was used to compare the positive rates and genotypes of norovirus among different specimen types, genders of children, and different age groups. Results: Among the 1 213 samples were collected, 215 samples were positive for norovirus, with a positivity rate of 17.7% for the whole year. The peak of norovirus infection observed mainly in the cold seasons, as the positive rates were 28.6% (18/63), 26.2% (16/61), 22.8% (77/338) and 17.1% (89/520) in January, October, November and December, respectively. The positive rate of norovirus in fecal sample was significantly higher than that in vomit sample (χ2 = 9.692, P<0.01). There was no significant difference between genders (χ2=0.041, P>0.05), but significant difference was found between age groups with the highest rate in the 6-48 months group (χ²=103.112, P<0.01). Three genogroups (GⅠ, GⅡ and GⅨ) of the circulating virus were detected by G-gene typing, and GⅡgenogroup was predominant, accounting for 98.5% (196/199). Among the GⅡ positive samples, genotype GⅡ.4 Sydney (55.1%, 108/196) was the most common, followed by GⅡ.2 (29.6%, 58/196), while the GⅡ.3 norovirus (10.2%, 20/196) which was common in previous years was not as much as before. Based on the P-type, GⅡ.P16 was predominant (61.5%, 96/156), followed by GII.P31 (19.9%, 31/156). The dual genotyping revealed that GⅡ.4 Sydney [P16] (36.4%, 56/154) and GⅡ.2 [P16] (24.7%, 38/154) were predominant. Conclusion: The prevalence of norovirus in children in 2020 in Beijing is not much different from those of the previous years, but the genotypes composition has changed significantly, and there are multiple genotypes circulating simultaneously.

[Confirmation and analysis of 2 398 positive results of cell-free fetal DNA].

Objective: To explore the clinical application value and accuracy of cell-free fetal DNA (cff-DNA) technique in prenatal screening. Methods: The results of quantitative fluorescent PCR (QF-PCR) and karyotype of amniotic fluid cells were analyzed retrospectively in 2 398 monocyesis pregnant women who had been amniocentesis at the First Affiliated Hospital of Zhengzhou University from May 2013 to December 2019, and the results of 359 cases who had been examined by single-nucleotide polymorphism array (SNP array). Results: Cff-DNA test of 2, 398 cases indicated 987 cases of trisomy 21, 351 cases of trisomy 18, 135 cases of trisomy 13, 566 cases of sex chromosome abnormality, and 359 cases of other chromosome abnormality. Chromosome karyotype analysis detected 826 cases of trisomy 21, 213 cases of trisomy 18, 17 cases of trisomy 13, 221 cases of sex chromosome abnormality, and 26 cases of other chromosome abnormality. The detection rate were 83.69% (826/987), 60.68% (213/351), 12.59% (17/135), 39.04% (221/566) and 7.24% (26/359), respectively. QF-PCR detected 1 046 cases of trisomy and 188 cases of sex chromosomes abnormality, and the detection rate was 99.05% (1 046/1 056) and 85.07% (188/221), respectively. Compared with the abnormal number detected by chromosome karyotype analysis, 10 cases of trisomeric chimerism and 24 cases of sex chromosome were missed by QF-PCR. Among the 359 other chromosomal abnormalities detected by SNP array, 64 cases were consistent with the results of cff-DNA, and the detection rate was 17.83% (64/359), which was 10.59% higher than the karyotype result. Conclusions: Karyotype analysis is the gold standard for diagnosing chromosomal abnormalities. QF-PCR could diagnose common chromosome aneuploidy rapidly and accurately, and it could be used as an auxiliary detection technique for karyotype analysis. The incidence of sex chromosome chimerism is high, so missed diagnosis should be warned. SNP array could be given priority to verify chromosome microdeletion or microduplication detected by cff-DNA.

[Investigation of pathogenic agents causing acute respiratory tract infections in pediatric patients in a children's hospital assigned for case screening in Beijing during the outbreak of COVID-19].

Objective: To investigate the spectrum of pathogenic agents in pediatric patients with acute respiratory infections (ARI) during the outbreak of coronavirus infectious diseases 2019 (COVID-19). Methods: Three groups of children were enrolled into the prospective study during January 20 to February 20, 2020 from Capital Institute of Pediatrics, including children in the exposed group with ARI and epidemiological history associated with COVID-19 from whom both pharyngeal and nasopharyngeal swabs were collected, children in the ARI group without COVID-19 associated epidemiological history and children in the screening group for hospital admission, with neither COVID-19 associated epidemiological history nor ARI. Only nasopharyngeal swabs were collected in the ARI group and screening group. Each group is expected to include at least 30 cases. All specimens were tested for 2019-nCoV nucleic acid by two diagnostic kits from different manufacturers. All nasopharyngeal swabs were tested for multiple respiratory pathogens, whilst the results from the ARI group were compared with that in the correspondence periods of 2019 and 2018 used by t or χ(2) test. Results: A total of 244 children were enrolled into three groups, including 139 males and 105 females, the age was (5±4) years. The test of 2019-nCoV nucleic acid were negative in all children, and high positive rates of pathogens were detected in exposed (69.4%, 25/36) and ARI (55.3%, 73/132) groups, with the highest positive rate for mycoplasma pneumoniae (MP) (19.4%, 7/36 and 17.4%, 23/132, respectively), followed by human metapneumovirus (hMPV) (16.7%, 6/36 and 9.8%, 13/132, respectively). The positive rate (11.8%, 9/76) of pathogens in the screening group was low. In the same period of 2019, the positive rate of pathogens was 83.7% (77/92), with the highest rates for respiratory syncytial virus (RSV) A (29.3%, 27/92), followed by influenza virus (Flu) A (H1N1) (19.6%, 18/92) and adenovirus (ADV) (14.1%, 13/92), which showed significant difference with the positive rates of the three viruses in 2020 (RSV A: χ(2)=27.346, P<0.01; FluA (H1N1): χ(2)=28.083, P<0.01; ADV: χ(2)=7.848, P=0.005) . In 2018, the positive rate of pathogens was 61.0% (50/82), with the highest rate for human bocavirus (HBoV) (13.4%, 11/82) and followed by ADV (11.0%, 9/82), and significant difference was shown in the positive rate of HBoV with that in 2020 (χ(2)=6.776, P=0.009). Conclusions: The infection rate of 2019-nCoV is low among children in Beijing with no family clustering or no close contact, even with epidemiological history. The spectrum of pathogens of ARI in children during the research period is quite different from that in the previous years when the viral infections were dominant. MP is the highest positively detected one among the main pathogens during the outbreak of COVID-19 in Beijing where there is no main outbreak area.

[Correlation between human bocavirus 2 infection in children and acute diarrhea in Beijing].

Objective: To investigate the relationship between human bocavirus 2 (HBoV2) infection and acute diarrhea in children younger than 5 years of age in a case-control study. Methods: This was a prospective case-control study. During May 2016 to December 2016, fecal specimens were collected from children ≤5 years of age with acute diarrhea who visited the Affiliated Children's Hospital of Capital Institute of Pediatrics (case group), or from children ≤5 years of age without diarrhea from Longtan Community Medical Service Center, Beijing (control group). The case group (n=240) and the control group (n=240) were divided into 8 age subgroups: ≤1 month old, >1-3 months old, >3-6 months old, >6-12 months old,>1-2 years old,>2-3 years old,>3-4 years old and >4-5 years old, and there were 30 cases in each age subgroup. The specimens were tested for 7 types of diarrhea-associated viruses, especially for HBoV2 by real-time PCR method. The HBoV2 viral load was predicted according to the cycle threshold (Ct). Finally, t-test was used to compare the differences between groups. Results: In the case group (n=240), the positive rate of norovirus was 16.7% (40 cases); rotavirus, 10.8% (26 cases); HBoV2, 7.5% (18 cases); adenovirus, 7.1% (17 cases); astrovirus, 6.3% (15 cases); parachovirus, 3.8% (9 cases); and Aich virus, 0.4% (1 case). The positive rates of HBoV2 in case group (7.5%, 18 cases) and control group (5.0%, 12 cases) showed no significant difference (χ(2)=1.280, P=0.258), as well as in different age groups (all P>0.05) . However, the mean viral load of the HBoV2 in the case group (1×10(9)copies/L with cycle threshold (Ct) 25.8) was higher than that of control group (1×10(5)copies/L with Ct 33.8), showing a significant difference (t=0.597, P=0.000). Conclusions: Norovirus and rotavirus are still the important viral pathogens in children with acute diarrhea. A higher load of HBoV2 may indicate a higher risk of acute diarrhea in children ≤5 years of age in Beijing.

[Pathogen spectrum in enteroviral infections among children in Beijing from 2010 to 2016].

Objective: To understand the epidemiological and etiological characteristics of enterovirus (EV)-associated diseases among children in Beijing from 2010 to 2016. Methods: This was a repeated cross-sectional study. The throat swabs were collected from children with probable EV-associated diseases at the Children' s Hospital Affiliated to Capital Institute of Pediatrics from 2010 to 2016. The samples were sent for pan-EV, enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) detection by real-time fluorescence reverse transcription polymerase chain reaction (RT-PCR) . The viral types of non-EV-A71 and non-CV-A16 EV-positive samples were identified using modified RT-PCR and sequencing with CV-A6, EV-A/B group and 5 'UTR universal primers. The constituent ratios of the prevalence of different EV types in different age and gender groups were compared. Results: Of the 2 703 throat swabs, 1 992 (73.7%) samples were positive for EV, including EV-A71 (19.1%, 516/2 703), CV-A16 (24.3%, 658/2 703), CV-A6 (22.2%, 600/2 703), CV-A10 (4.5%, 122/2 703) and other types of EV (3.5%, 95/2 703). There was 1 case of EV-A71 and CV-A16 co-infection. The positive detection rate of EV-A group (excluding EV-A71, CV-A16, CV-A6 and CV-A10) increased from 11.3% (7/62) to 95.2% (59/62) after using the modified VP1-specific primers and PCR amplification conditions. During the period between 2010 and 2012, CV-A16 and EV-A71 predominated in EV-positive samples. However, CV-A6 accounted for 60.7% (68/112) in 2013, much higher than CV-A16 (23.2%, 26/112) and EV-A71 (12.5%, 14/112). In 2014, EVs were mainly of CV-A16 and EV-A71, but CV-A6 was the predominant type in 2015 (68.2%, 232/340) and in 2016 (38.6%, 151/391). The epidemic season of EVs was mostly from April to August, but CV-A6 showed a small epidemic peak from October to November. The male-to-female ratio of EV-positive patients was 1.50∶1, and EV-associated diseases mostly occurred in children under 5 years of age. Younger children were more susceptible to CV-A6 than to EV-A71 and CV-A16. Conclusions: From 2010 to 2016, there was a significant change in the spectrum of EVs in children with EV-associated diseases in Beijing. Since 2013, non-EV-A71 and non-CV-A16 increased, and CV-A6 gradually became one of the major pathogens of EV-associated diseases. The modified PCR primers and amplification conditions can effectively improve the reliability of test results.

[Epidemiological features of prevalent influenza A viruses in children with influenza-like illness during the 2004-2017 season in Beijing].

Objective: To analyze and compare the epidemiological features of prevalent influenza A viruses in children in Beijing during 13 consecutive surveillance seasons from 2004 to 2017. Methods: This was a repeated cross section study. Throat swabs were collected weekly from children with influenza-like illnesses (ILI) who presented to the outpatient/emergency department of Children's Hospital, Capital Institute of Pediatrics during the period from September, 2004 to August, 2017. All of the specimens were inoculated into Madin Darby canine kidney (MDCK) cells to isolate influenza viruses followed by identifying different types of influenza viruses with reference antisera by hemagglutination-inhibition assay. Descriptive statistics, t test and chi-square test were used to analyze the characteristics of prevalent influenza and characteristics of children infected with different types of influenza viruses. Results: Out of 10 984 specimens from ILI tested for influenza viruses, 1 052 (9.6%) were positive for influenza A viruses, and the positive rate was higher than that of influenza B viruses (6.7%, 741/10 984). Out of 1 052 cases positive for influenza A viruses, 70 cases of seasonal H1N1, 302 cases of 2 009 pandemic H1N1 and 680 cases of H3N2 were identified. The mean age of children with influenza A was (4.2±2.9) years, in whom 55.5% (584/1 052) were male. The mean age of children infected with seasonal H1N1, 2009 pandemic H1N1 and H3N2 was (4.6±2.1) , (4.3±3.1) and (4.2±2.9) years, respectively. There was no significant difference in the mean age among children infected with different subtypes of influenza A viruses (seasonal H1N1 vs. H3N2: t=1.139, P=0.255; 2009 pandemic H1N1 vs. H3N2: t=0.631, P=0.528; seasonal H1N1 vs. 2009 pandemic H1N1: t=0.720, P=0.472), while the mean age of children with influenza B was higher than that of the patients with influenza A ((5.2±2.7) vs. (4.2±2.9) years, t=7.120, P=0.000). The infection rate of influenza A in children with each age group was significantly different from that of influenza B. The infection rate of 2009 pandemic H1N1 and H3N2 increased with age, except for the patients of 0-6 months. Meanwhile, the infection rate of H3N2 in children aged 6 months to 12 years was higher than that of seasonal H1N1 and 2009 pandemic H1N1 (all P<0.05). The influenza A epidemic peaked earlier than that of influenza B when the positive rate of influenza A was higher than that of influenza B, and vice versa. After 2009, circulating strain was substituted by 2009 pandemic H1N1 virus with higher positive rate, while previous seasonal H1N1 had not been detected. The 2009 pandemic H1N1 circulated at high level in two consecutive seasons, which was followed by low level in next season. H3N2 epidemic peaked mostly in winter and spring each year, however, the epidemic wave of H3N2 with high virulence occurred so early in the summer in the year of 2009 H1N1 pandemic. Conclusions: The characteristics of prevalent influenza A viruses in children were different among 13 surveillance seasons from 2004 to 2017 in Beijing. The 2009 pandemic H1N1 and H3N2 became the predominant strains of influenza A virus.

[Molecular biological and clinical characteristics of respiratory syncytial virus in children with bronchiolitis].

Objective: To investigate the clinical characteristics of respiratory syncytial virus(RSV)bronchiolitis and molecular biological characteristics of RSV in children in Beijing. Method: In a systematic retrospective study, 2 296 nasopharyngeal aspirates (NPA) were collected from children diagnosed with bronchiolitis from July 2006 to June 2016 for respiratory virus screening using direct immunofluorescence assay (DFA). For specimens positive for RSV, subgroup A or B was confirmed by real time RT-PCR and genotype of RSV was determined by amplifying the full G glycoprotein gene and sequencing. Clinical data were evaluated by the modified Tal score to compare the severity between RSV subtypes, as well as genotypes. Statistical analyses were performed using t test, Mann-Whitney U test and χ(2) test. Result: In 2 296 bronchiolitis cases, 961(41.9%) were RSV positive, including 719(74.8%) RSV A and 236 (24.6%) RSV B. The dominant RSV subtype changed from year to year: A-A-B-B-A-A-B-AB-A-AB and more bronchiolitis cases were identified in RSV A dominant years. Six genotypes of RSV A (NA1, NA2, NA3, NA4, GA5 and ON1) and 5 genotypes of RSV B (BA3, BA7, BA9, BA10 and CB1) were prevalent in Beijing. The dominant genotypes of RSV A were NA1 (55.9%) with high rates (50.0%-100%) before 2014 and ON1 (39.1%), mainly detected after 2014, while BA9 (90.6%) was the absolute dominant RSV B genotype. No significant difference in the severity of bronchiolitis was shown between cases of RSV A and B. Children positive for NA1 were more likely to stay longer in hospital (Median time: 8 days) compared to the group positive for ON1(Median time: 6 days ) (U=1.035, P=0.005) and had higher proportion of moderate to severe degree symptoms (Moderate: 41.0%, Severe: 10.0%) compared with ON1 group (Moderate: 22.9%, Severe: 4.3%) (U=9.785, P=0.008). In the group positive for ON1, more children had fever (ON1: 38.6%, NA1: 15.0%) (χ(2)=11.064, P=0.001) and more were younger than 3 months(ON1: 54.3%, NA1: 33.0%) (χ(2)=77.408, P<0.001). Conclusion: The dominant RSV subgroup changed from year to year with a shifting pattern. The correlation between RSV genotypes and the severity of disease was documented in the study.

[Clinical value of a rapid respiratory syncytial virus antigen detection in point-of-care testing].

Objective: To evaluate the clinical value of a rapid respiratory syncytial virus (RSV) antigen detection in point-of-care testing (POCT). Method: A total of 209 specimens, including 78 throat swabs (TS) and 131 nasopharyngeal aspirates (NPAs), were collected from inpatients who visited the Children's Hospital Affiliated to the Capital Institute of Pediatrics and were diagnosed as acute respiratory infection from 5 January to 7 February, 2015. These specimens were tested for RSV by a rapid antigen detection kit which was compared with reverse transcription polymerase chain reaction (RT-PCR) and direct immunofluorescence assay (DFA) for RSV detection. Result: Compared with DFA for NPAs, the sensitivity and specificity of rapid antigen detection were 83.9% and 97.3%, respectively, with Kappa value of 0.86; Compared with RT-PCR, the sensitivity (NPAs, 74.2%; TS, 77.8%) and specificity (NPAs, 100.0%; TS, 92.0%) of rapid antigen detection were high, too, with Kappa value of 0.74 in NPAs and 0.62 in TS. However, the RSV positive rate of rapid antigen detection in TS (21.7%) from pediatric patients with acute lower respiratory tract infection was lower than that in NPAs (78.3%), as well as that of RT-PCR (7.3% in TS verse 78% in NPAs). The RSV rapid antigen detection kit can be finished in about 10 minutes. Conclusion: With characteristics of high specificity, high sensitivity, being rapid, efficient and easy to operate in comparison with DFA and RT-PCR, RSV rapid antigen detection in this study is suitable for POCT. For pediatric patients with acute respiratory tract infection, NPA was better than TS for RSV detection.

[Prevalence characteristics of influenza viruses in children in Beijing during 2014-2015 and 2015-2016 influenza seasons].

OBJECTIVE: To compare the prevalence characteristics of influenza viruses in children in Beijing during 2014-2015 and 2015-2016 influenza seasons. METHOD: Throat swabs were collected weekly from children with influenza-like illnesses who visited in Children's Hospital affiliated to Capital Institute of Pediatrics during the period from September 2014 to May 2016.Influenza viruses A and B viruses were detected by real-time RT-PCR, followed by identification of H3N2, H1N1pdm, B/Victoria-like and B/Yamagata-like.The prevalence characteristics of influenza viruses was estimated by means of descriptive statistics.The t test and chi-square test were used to compare median age and gender ratio of infected children among different types of influenza viruses. RESULT: Out of 1 821 throat swabs collected, 139 (7.6%) were positive for H3N2 and 43 (2.4%) for H1N1pdm and 204 (11.2%) for influenza B virus, including 108 for B/Victoria-like and 96 for B/Yamagata-like.The median age of H1N1pdm infected children ((3.3±2.2) years) was significantly younger than that of H3N2 ((4.7±3.2) years) and influenza B virus((4.9±2.8) years) (H1N1pdm vs. H3N2: t=2.848, P=0.002; H1N1pdm vs. influenza B, t=3.682, P=0.000). Two epidemic peaks were presented in 2014-2015 influenza season, dominated definitely by H3N2 and B/Yamagata-like, respectively, while one delayed peak started at the 51(st) week, 2015, co-circulated with H3N2, H1N1pdm and influenza B viruses, among which B/Victoria-like virus was predominant during the 2015-2016 season. CONCLUSION: Prevalence characteristics of influenza viruses are different between 2014-2015 and 2015-2016 influenza seasonal epidemics in children in Beijing. It is important to monitor the genetic variations of influenza viruses and to keep close attention to influenza B virus as well as influenza A virus.