[Hospitalization rates for influenza-associated severe acute respiratory illness in children younger than five years old in Suzhou of China, 2016-2018]

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.

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.