Influenza-associated Hospitalization in Children Younger Than 5 Years of Age in Suzhou, China, 2011-2016

The CD19+ B cell as a marker for the febrile children infected with influenza A and Omicron variant

H3N2 and Omicron are common pathogens of respiratory infections in children. This study aimed to explore dynamic changes of lymphocyte subsets and the diagnostic value of CD19+ B cell in children infected with influenza A and Omicron. One hundred and sixty-five in-patients with H3N2, 175 in-patients with Omicron variant, and 50 age-matched healthy children from Children's Hospital of Soochow University were included in this study. The participants underwent 13 respiratory pathogens by DNA polymerase chain reaction (PCR), sputum culture, severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) DNA PCR, routine blood, and lymphocyte subset assays within 24 h of admission. The neutrophils, neutrophil-to-lymphocyte ratio, and monocyte-to-lymphocyte ratio in the H3N2 and Omicron groups were significantly higher than in the control groups (p < 0.05). However, the lymphocytes and eosinophils in the H3N2 and Omicron groups were lower than the control groups (p < 0.05). The CD3+ T cell, CD3+ CD4+ T cell, CD3+ CD8+ T cell, CD3- CD19+ B cell, and natural killer cell were lower in the H3N2 and Omicron groups than in the control group (p < 0.05). The CD3- CD19+ cell in the Omicron group was higher than that in the H3N2 group but lower than that in the control group (p < 0.05). In addition, CD3- CD19+ cell had good diagnostic value for H3N2 (area under the receiver operating characteristic curve = 0.902, p < 0.05). The children with H3N2 were more likely to have lower lymphocytes than children with Omicron. Additionally, B-cell count had good diagnostic value for H3N2.

Viral and Atypical Pathogen's Epidemiology of a Large Cohort of Patients with Acute Respiratory Tract Infections in Shaanxi Province, Northwest China

Purpose

To analyze and summarize the etiological and epidemiological characteristics of acute respiratory tract infections (ARIs) in northwest China to improve the clinical management and prevention of local ARIs.

Methods

Patients with ARIs in Shaanxi Province, from January 2014 to December 2018, were retrospectively analyzed. Indirect immunofluorescence assay (IFA) was used to detect the IgM antibody of eight respiratory pathogens.

Results

A total of 15,543 eligible patients were included in this study. Overall, 36.01% of the patients (5597/15543) were positive for at least one of eight pathogens, among which single and mixed infections accounted for 74.65% (4178/5597) and 25.35% (1419/5597), respectively. Mycoplasma (MP) showed the highest detection rate (18.12%), followed by influenza virus B (Flu B, 11.65%), chlamydia (CP, 7.00%), respiratory syncytial virus (RSV, 4.18%), parainfluenza virus (PIV, 2.83%), influenza virus A (Flu A, 1.69%), legionella (LP, 1.00%) and adenovirus (ADV, 0.70%). Flu B (17.54%, 759/4327) was the most prevalent virus in patients aged less than 18 years. In addition, common respiratory infections with higher detection rates were found in autumn (39.65%), followed by winter (37.37%), summer (36.21%) and spring (30.91%). There were significant differences in the detection rates of pathogens in different seasons (P < 0.001).

Conclusion

These findings serve as a reference for local health authorities to develop further plans for the prevention and control of ARIs.

Impact of COVID-19 pandemic on influenza virus prevalence in children in Sichuan, China

We performed a retrospective analysis of influenza A and B virus antigen detection data in children in Sichuan Province from January 2019 to December 2021, with the goal of studying the impact of the COVID-19 pandemic on influenza circulation in children in Sichuan, China. During the pandemic, both the number of specimens and the positive rates of the influenza virus fell dramatically. The positivity for influenza A virus decreased from 22.5% in 2019 to 9.9% in 2020 to 0.2% in 2021 (p < 0.001). The lowest and highest positive rates for the influenza B virus occurred in 2020 and 2021, respectively, with a statistically significant 3-year comparison (p < 0.001). During the pandemic, the annual positivity remained higher in school-age than in preschoolers, while there was no difference in the annual positivity between the two gender groups, both consistent with the prepandemic results. During the pandemic, the seasonality of influenza A and B was different from that before the pandemic. In 2019, the epidemic season for influenza A was autumn and winter, while the epidemic season for influenza B was winter and spring. Seasonal changes in influenza A were insignificant after the pandemic, and influenza B became predominant in 2021, with a high prevalence in the autumn. Although influenza activity decreased during the COVID-19 pandemic, one should be on the lookout for a possible rebound in influenza circulation in the future.

Hospitalization of Children Aged <5 Years Due to Influenza: Study Based on the National Hospitalization Registry

Background: Influenza constitutes a significant health care burden that can be related to an increased morbidity and mortality. The aim of the study is to show up-to-date information on influenza hospitalization cases in Poland in children aged <5 years. Methods: The data used in the study were hospitalization records from 2015−2019, which had been gathered in a Nationwide General Hospital Morbidity Study and made available by the National Institute of Public Health. Results: 8565 records of patients with influenza were subject to analysis. The mean and median age of the patients were 2.2 and 2.1 years, respectively. Influenza hospitalization incidence was estimated at 90 per 100,000 person-years (PY) in children aged <5 years. The number of hospitalization cases was significantly higher in patients living in urban regions than in those living in rural regions (97 vs. 77 per 100,000 PY; p < 0.001). The age of patients living in urban regions was significantly lower than the age of patients living in rural regions (2.2 vs. 2.3 years; p < 0.001). A statistically significant increase in hospitalization was observed. Conclusions: The reported increasing trend in hospitalizations indicates the need to take focused measures. Presented data may be useful in comparative analyses in a European context.

Hospitalization rate of respiratory syncytial virus-associated acute lower respiratory infection among young children in Suzhou, China, 2010-2014

Background

There is a limited amount of data in China on the disease burden of respiratory syncytial virus‐ (RSV) associated acute lower respiratory infection (ALRI) among young children. This study aimed to estimate the hospitalization rate of RSV‐associated ALRI (RSV‐ALRI) among children aged 0–59 months in Suzhou, China.

Methods

All cases from children hospitalized with ALRI who were aged 0–59 months in Suzhou University Affiliated Children's Hospital during January 2010 to December 2014 were retrospectively identified. Detailed diagnosis and treatment data were collected by reviewing each individual's medical chart. In accordance with the World Health Organization (WHO) influenza disease burden estimation, the hospitalization rate of RSV‐ALRI among children aged 0–59 months in Suzhou, China, was then estimated.

Results

Out of the 28,209 ALRI cases, 19,317 (68.5%) were tested for RSV, of which the RSV positive proportion was 21.3% (4107/19,317). The average hospitalization rate of RSV‐ALRI for children aged 0–59 months was 14 (95% confidence interval [CI]:14–14)/1000 children years, and that for children aged 0–5, 6–11, 12–23, and 24–59 months were 70 (95% CI: 67–73), 31 (95% CI: 29–33), 11 (95% CI: 10–12), and 3 (95% CI: 3–3)/1000 children years, respectively.

Conclusion

A considerable degree of RSV‐ALRI hospitalization exists among children aged 0–59 months, particularly in those under 1 year of age. Therefore, an effective monoclonal antibody or vaccine is urgently needed to address the substantial hospitalization burden of RSV infection.

Development of influenza-associated disease burden pyramid in Shanghai, China, 2010-2017: a Bayesian modelling study

OBJECTIVES

Negative estimates can be produced when statistical modelling techniques are applied to estimate morbidity and mortality attributable to influenza. Based on the prior knowledge that influenza viruses are hazardous pathogens and have adverse health outcomes of respiratory and circulatory disease (R&C), we developed an improved model incorporating Bayes' theorem to estimate the disease burden of influenza in Shanghai, China, from 2010 to 2017.

DESIGN

A modelling study using aggregated data from administrative systems on weekly R&C mortality and hospitalisation, influenza surveillance and meteorological data. We constrained the regression coefficients for influenza activity to be positive by truncating the prior distributions at zero.

SETTING

Shanghai, China.

PARTICIPANTS

People registered with R&C deaths (450 298) and hospitalisations (2621 787, from 1 July 2013), and with influenza-like illness (ILI) outpatient visits (342 149) between 4 January 2010 and 31 December 2017.

PRIMARY OUTCOME MEASURES

Influenza-associated disease burden (mortality, hospitalisation and outpatient visit rates) and clinical severity (outpatient-mortality, outpatient-hospitalisation and hospitalisation-mortality risks).

RESULTS

Influenza was associated with an annual average of 15.49 (95% credibility interval (CrI) 9.06-22.06) excess R&C deaths, 100.65 (95% CrI 48.79-156.78) excess R&C hospitalisations and 914.95 (95% CrI 798.51-1023.66) excess ILI outpatient visits per 100 000 population in Shanghai. 97.23% and 80.24% excess R&C deaths and hospitalisations occurred in people aged ≥65 years. More than half of excess morbidity and mortality were associated with influenza A(H3N2) virus, and its severities were 1.65-fold to 3.54-fold and 1.47-fold to 2.16-fold higher than that for influenza A(H1N1) and B viruses, respectively.

CONCLUSIONS

The proposed Bayesian approach with reasonable prior information improved estimates of influenza-associated disease burden. Influenza A(H3N2) virus was generally associated with higher morbidity and mortality, and was relatively more severe compared with influenza A(H1N1) and B viruses. Targeted influenza prevention and control strategies for the elderly in Shanghai may substantially reduce the disease burden.

Influenza-associated disease burden in mainland China: a systematic review and meta-analysis

Influenza causes substantial morbidity and mortality. Many original studies have been carried out to estimate disease burden of influenza in mainland China, while the full disease burden has not yet been systematically reviewed. We did a systematic review and meta-analysis to assess the burden of influenza-associated mortality, hospitalization, and outpatient visit in mainland China. We searched 3 English and 4 Chinese databases with studies published from 2005 to 2019. Studies reporting population-based rates of mortality, hospitalization, or outpatient visit attributed to seasonal influenza were included in the analysis. Fixed-effects or random-effects model was used to calculate pooled estimates of influenza-associated mortality depending on the degree of heterogeneity. Meta-regression was applied to explore the sources of heterogeneity. Publication bias was assessed by funnel plots and Egger’s test. We identified 30 studies eligible for inclusion with 17, 8, 5 studies reporting mortality, hospitalization, and outpatient visit associated with influenza, respectively. The pooled influenza-associated all-cause mortality rates were 14.33 and 122.79 per 100,000 persons for all ages and ≥ 65 years age groups, respectively. Studies were highly heterogeneous in aspects of age group, cause of death, statistical model, geographic location, and study period, and these factors could explain 60.14% of the heterogeneity in influenza-associated mortality. No significant publication bias existed in estimates of influenza-associated all-cause mortality. Children aged < 5 years were observed with the highest rates of influenza-associated hospitalizations and ILI outpatient visits. People aged ≥ 65 years and < 5 years contribute mostly to mortality and morbidity burden due to influenza, which calls for targeted vaccination policy for older adults and younger children in mainland China.

Estimated influenza illnesses and hospitalizations averted by influenza vaccination among children aged 6-59 months in Suzhou, China, 2011/12 to 2015/16 influenza seasons

BACKGROUND

There are few estimates of vaccination-averted influenza-associated illnesses in China.

METHODS

We used a mathematical model and Monte Carlo algorithm to estimate numbers and 95% confidence intervals (CI) of influenza-associated outcomes (hospitalization, illness, and medically-attended (MA) illness) averted by vaccination among children aged 6-59 months in Suzhou from October 2011-September 2016. Influenza illnesses included non-hospitalized MA influenza illnesses and non-MA influenza illnesses. The numbers of influenza-associated outcomes averted by vaccination were the difference between the expected burden if there were no vaccination given and the observed burden with vaccination. The model incorporated the disease burden estimated based on surveillance data from Suzhou University Affiliated Children's Hospital (SCH) and data from health utilization surveys conducted in the catchment area of SCH, age-specific estimates of influenza vaccination coverage in Suzhou from the Expanded Program on Immunization database, and influenza vaccine effectiveness estimates from previous publications. Averted influenza estimations were presented as absolute numbers and in terms of the prevented fraction (PF). A hypothetical scenario with 50% coverage (but identical vaccine effectiveness) over the study period was also modeled.

RESULTS

In ~250,000 children, influenza vaccination prevented an estimated 731 (CI: 549-960) influenza hospitalizations (PF: 6.2% of expected, CI: 5.8-6.6%) and 10,024 (7593-12,937) influenza illnesses (PF: 6.5%, 6.4-6.7%), of which 8342 (6338-10,768) were MA (PF: 6.6%, 6.4-6.7%) from 2011 to 2016. The PFs declined each year along with decreasing influenza vaccination coverage. If 50% of the study population had been vaccinated over time, the estimated numbers of averted cases during the study period would have been 4059 (3120-5762) influenza hospitalizations (PF: 27.2%, 26.4-27.9%) and 56,215 (42,925-78,849) influenza illnesses (PF: 28.5%, 28.3-28.7%), of which 46,596 (35,662-65,234) would be MA (PF: 28.5%, 28.3-28.7%).

CONCLUSION

Influenza vaccination is estimated to have averted influenza-associated illness outcomes even with low coverage in children aged 6-59 months in Suzhou. Increasing influenza vaccination coverage in this population could further reduce illnesses and hospitalizations.

Review of the status and challenges associated with increasing influenza vaccination coverage among pregnant women in China

Influenza vaccination coverage in pregnant women in China remains low. In this review, we first provide an overview of the evidence for the use of influenza vaccination during pregnancy. Second, we discuss influenza vaccination policy and barriers to increased seasonal influenza vaccination coverage in pregnant women in China. Third, we provide case studies of successes and challenges of programs for increasing seasonal influenza vaccination in pregnant women from other parts of Asia with lessons learned for China. Finally, we assess opportunities and challenges for increasing influenza vaccination coverage among pregnant women in China.

Epidemiological features and trends of influenza incidence in mainland China: A population-based surveillance study from 2005 to 2015

OBJECTIVES

To investigate epidemiological features and trends of influenza incidence with 1,173,640 cases in mainland China from 2005 to 2015.

METHODS

Incidence and mortality data for influenza from 2005 to 2015 were provided by the data-center of China public health science and covered a population of about 1.3 billion people from 31 provinces and regions in mainland China. Joinpoint regression and exploratory spatial data analyses were used to examine the incidence trends from 2005 to 2015.

RESULTS

The first upsurge in influenza cases occurred in 2009, and the highest incidence of influenza occurred in 2014 (15.9045 cases/100,000 people). The average incidence per year from 2009 to 2015 was threefold higher than that from 2005 to 2008 (10.5308 vs 3.4589 cases/100,000 people; incidence rate ratio=3.0446). The joinpoint regression results showed that there was an increasing influenza incidence trend from 2005 to 2015 (annual change in percentage=13.6%, 95%CI 2.2-26.3, p=0.0236). The seasonal pattern analysis showed that influenza typically occurred in winter and spring during each monitoring year, peaking from November to March the next year.

CONCLUSIONS

This study will help governments to make valuable decisions in allocating scarce resources and providing strategies to limit the spread of influenza.