Lung Function in Wheezing Infants after Acute Lower Respiratory Tract Infection and Its Association with Respiratory Outcome

Background： Wheezing is common in early childhood and remains an important health concern. The aim of this study was to assess the lung function of wheezing infants and to investigate the relationship between lung function and respiratory outcome. Methods： Infants 〈2 years of age with acute lower respiratory tract infection （ALRTI） who had undergone lung function tests were included in the study. They were assigned to wheeze or no wheeze group based on physical examination. Infants without any respiratory diseases were enrolled as controls. Lung function was measured during the acute phase and 3 months after ALRTI. One-year follow-up for infants with ALRTI was achieved. Results： A total of 252 infants with ALRTI who had acceptable data regarding tidal breathing were included in the final analysis. Compared with the control and the no wheeze groups, infants in the wheeze group had significantly decreased time to peak tidal expiratory flow as a percentage of total expiratory time （TPTEF/TE） （20.1 1 6.4% vs. 34.4 ± 6.2% and 26.4 ±8.3%, respectively, P 〈 0.0001） and significantly increased peak tidal expiratory flow （PTEF） （90.7 ± 26.3 ml/s vs. 79.3 ± 18.4 ml/s and 86.1 ± 28.0 ml/s, respectively, P 〈 0.01）, sReff and Reff. The infants in the wheeze group still had lower TPTEF/TE and volume to peak tidal expiratory flow as a percentage of total expiratory volume （VPTEF/VE） than the no wheeze infants 3 months after the ALRT1. Moreover, there was a significant inverse relationship between TPTEF/TE, VPTEF/VE, and the recurrence of wheezing and pneumonia. Conclusions： Impaired lung function was present in wheezing infants with ALRTI and the deficits persisted. In addition, the lower level of TPTEF/TE and VPTEF/VE was a risk factor for poor respiratory outcome.

Clinical characteristics and molecular epidemiology of human metapneumovirus in children with acute lower respiratory tract infections in China, 2017 to 2019: A multicentre prospective observational study

Human metapneumovirus(HMPV) infection is one of the leading causes of hospitalization in young children with acute respiratory illness. In this study, we prospectively collected respiratory tract samples from children who were hospitalized with acute lower respiratory tract infection in six hospitals in China from 2017 to 2019. HMPV was detected in 145 out of 2733 samples(5.3%) from the hospitalized children. The majority of HMPV-positive children were under the age of two(67.6%), with a median age of one year. HMPV can independently cause acute lower respiratory tract infection in young children, while all patients showed mild clinical symptoms. Of all the co-infected patients, HMPV was most commonly detected with enterovirus(EV) or rhinovirus(RhV)(38.0%),followed by respiratory syncytial virus(RSV)(32.0%). The highest detection rate occurred from March to May in both northern and southern China. Out of 145 HMPV positive samples, 48 were successfully typed, of which 36strains were subgrouped into subtypes A2c(75%), eight strains were included in subtype B1(16.7%), and four strains were included in subtype B2(8.3%). Moreover, 16 A2c strains contained 111-nucleotide duplications in the G gene. Twenty-seven complete HMPV genomes were successfully obtained, and 25(92.6%) strains belonged to subtype A2c, whereas one strain was included in subgroup B1 and another was included in subgroup B2. A total of 277 mutations were observed in the complete genomes of 25 A2c strains. All results presented here improve our understanding of clinical characteristics and molecular epidemiology of HMPV infection in children.

A multi-center study on Molecular Epidemiology of Human Respiratory Syncytial Virus from Children with Acute Lower Respiratory Tract Infections in the Mainland of China between 2015 and 2019

Human respiratory syncytial virus(RSV) is a major pathogen of acute lower respiratory tract infection among young children. To investigate the prevalence and genetic characteristics of RSV in China, we performed a molecular epidemiological study during 2015–2019. A total of 964 RSV-positive specimens were identified from 5529 enrolled patients during a multi-center study. RSV subgroup A(RSV-A) was the predominant subgroup during this research period except in2016. Totally, 535 sequences of the second hypervariable region(HVR-2) of the G gene were obtained. Combined with182 Chinese sequences from GenBank, phylogenetic trees showed that 521 RSV-A sequences fell in genotypes ON1(512),NA1(6) and GA5(3), respectively;while 196 RSV-B sequences fell in BA9(193) and SAB4(3). ON1 and BA9 were the only genotypes after December 2015. Genotypes ON1 and BA9 can be separated into 10 and 7 lineages, respectively. The HVR-2 of genotype ON1 had six amino acid changes with a frequency more than 10%, while two substitutions H258 Q and H266 L were co-occurrences. The HVR-2 of genotype BA9 had nine amino acid substitutions with a frequency more than10%, while the sequences with T290 I and T312 I were all from 2018 to 2019. One N-glycosylation site at 237 was identified among ON1 sequences, while two N-glycosylation sites(296 and 310) were identified in the 60-nucleotide duplication region of BA9. To conclusion, ON1 and BA9 were the predominant genotypes in China during 2015–2019. For the genotypes ON1 and BA9, the G gene exhibited relatively high diversity and evolved continuously.