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

Abstract

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.

Dynamics of influenza‐like illness under urbanization procedure and COVID‐19 pandemic in the subcenter of Beijing during 2013–2021

“…25 , 26 , 27 Under the stronger interconnection among intensive population with different living conditions, dynamic of ILI was confirmed to be aggravated, particularly among those susceptible populations like children and adolescents under 25 years. 1 , 15 , 28 , 29 ILI activity among people aged over 25 years remained at a low level, which is in line with previous studies. 15 , 29 , 30 It suggests that influenza prevention and control in newly developed urbanization areas should be focused at places like schools and kindergartens in facing the assault of increasing population diversity, mobility, and human contact.…”

“…31 As older adults aged over 65 years were claimed to be with the highest burden of influenza‐related death, the current prevention measures should be maintained as a solid issue. 1 And the correlation analysis further suggested that influenza vaccination offered positive efforts in preventing the school‐aged and elder population from ILI infection. This is in also in line with previous studies that indicate influenza vaccination shows effectiveness in ILI prevention.…”

“…Influenza virus is one of the most common pathogen that cause respiratory diseases, such as ILI, particularly in autumn and winter seasons in China. 1 About 290–450 thousand deaths are attributed to seasonal influenza worldwide. 2 , 3 Among the most impacted countries, three million ILI cases and over 80 000 ILI‐related deaths were estimated annually, even though marvelous efforts have been made to mitigate its impacts, such as etiological detection, routine epidemiological surveillance, or vaccination extension.…”

Epidemiological characteristics of notifiable respiratory infectious diseases in mainland China from 2010 to 2019

“…The mortality of seasonal in uenza in mainland China was from 0.012/100 000 in 2010 to 0.019/100 000 in 2019. However, it is estimated that in uenza-associated all-cause mortality was 14.33/100 000 in mainland China [27], which was much higher than the present study. Previous study pointed out that the death burden of seasonal in uenza had been underestimated, owing to the deaths of seasonal in uenza and other respiratory diseases that are di cult to distinguish [2].…”

The burden of seasonal influenza in Italy: A systematic review of influenza‐related complications, hospitalizations, and mortality

“…Excess death rates for elderly were estimated to be over six times higher than in general population with the most of influenza‐related deaths (65%–96%) occurring in persons 65+ 34,36 . These data were also confirmed by other systematic reviews 17,38 …”