Burden of influenza‐associated outpatient influenza‐like illness consultations in China, 2006‐2015: A population‐based study

Abstract

Background Human influenza virus infections cause a considerable burden of morbidity and mortality worldwide each year. Understanding regional influenza‐associated outpatient burden is crucial for formulating control strategies against influenza viruses. Methods We extracted the national sentinel surveillance data on outpatient visits due to influenza‐like‐illness (ILI) and virological confirmation of sentinel specimens from 30 provinces of China from 2006 to 2015. Generalized additive regression models were fitted to estimate influenza‐associated excess ILI outpatient burden for each individual province, accounting for seasonal baselines and meteorological factors. Results Influenza was associated with an average of 2.5 excess ILI consultations per 1000 person‐years (py) in 30 provinces of China each year from 2006 to 2015. Influenza A(H1N1)pdm09 led to a higher number of influenza‐associated ILI consultations in 2009 across all provinces compared with other years. The excess ILI burden was 4.5 per 1000 py among children aged below 15 years old, substantially higher than that in adults. Conclusions Human influenza viruses caused considerable impact on population morbidity, with a consequent healthcare and economic burden. This study provided the evidence for planning of vaccination programs in China and a framework to estimate burden of influenza‐associated outpatient consultations.

Disease burden and clinical severity of the first pandemic wave of COVID-19 in Wuhan, China

“…This indicates that during this time period, the Wuhan healthcare system considerably exceeded surge capacity, highlighting the importance and necessity of preparedness for sufficient healthcare resources. Moreover, there is a winter peak of consultations and hospitalizations related to respiratory diseases, such as seasonal influenza and respiratory syncytial virus 14,40,41 , which may have contributed to overwhelm the healthcare sector during the first wave of the COVID-19 epidemic.…”

“…(Fig. 5a-c and Supplementary Information File 5) In contrast, younger age groups were the most affected segment of the population during the 1918 and 2009 influenza pandemic, while both young and old individuals were the most affected during seasonal influenza epidemics [14][15][16][17][18][19][20][21][22][23][24][25][26] . The HFR (9.77%, 95% CI 9.41-10.10%) and sCHR (46.48%, 95% CI: 39.33-50.93%) were higher for COVID-19 than for the 2009 influenza pandemic (HFR: 2.6% in North America 26 ; sCHR: 1.44% in the USA 25 ) (Supplementary Information Files 3, 5).…”

“…The age profile of the Wuhan population was obtained from the China Statistic Yearbook 54 . To compare the burden of COVID-19 to baseline activity of acute respiratory infections, we obtained reference historical data on ILI surveillance in Hubei province and SARI surveillance in Jingzhou city, Hubei province 14,17,21 . Additionally, we collected the annual number of consultations in pediatric and internal medicine departments in Hubei, and the national number of pneumonia hospitalization rates from the Chinese Health Statistics Yearbook 55 .…”

Disease burden and clinical severity of the first pandemic wave of COVID-19 in Wuhan, China

“…The sCFR of COVID-19 was higher for adults aged ≥60 years than for the other age groups (9.09% vs. 0.36%-1.97%). (Fig.5a-5c and Supplementary Information File 5) In contrast, younger age groups were the most affected segment of the population during the 1918 and 2009 influenza pandemic, while both young and old individuals were the most affected during seasonal influenza epidemics 14,15,16,17,18,19,20,21,22,23,24,25,26 .…”

Using influenza surveillance networks to estimate state-specific prevalence of SARS-CoV-2 in the United States

“…Outpatient ILI surveillance has proven to be a useful tool for assessing the impact of influenza (6,7). When combined with the number of providers and patients in a given region, ILI surveillance allows estimation of influenza prevalence and severity (8)(9)(10)(11)(12)(13)(14). Studies of outpatient ILI have repeatedly demonstrated that confirmed influenza case rates underestimate disease burden, likely due to preferential testing of more severe cases (8,9,13,14).…”