The substantial hospitalization burden of influenza in central China: surveillance for severe, acute respiratory infection, and influenza viruses, 2010–2012

Abstract

BackgroundPublished data on influenza in severe acute respiratory infection (SARI) patients are limited. We conducted SARI surveillance in central China and estimated hospitalization rates of SARI attributable to influenza by viral type/subtype.MethodsSurveillance was conducted at four hospitals in Jingzhou, China from 2010 to 2012. We enrolled hospitalized patients who had temperature ≥37·3°C and at least one of: cough, sore throat, tachypnea, difficulty breathing, abnormal breath sounds on auscultation, sputum production, hemoptysis, chest pain, or chest radiograph consistent with pneumonia. A nasopharyngeal swab was collected from each case-patient within 24 hours of admission for influenza testing by real-time reverse transcription PCR.ResultsOf 17 172 SARI patients enrolled, 90% were aged <15 years. The median duration of hospitalization was 5 days. Of 16 208 (94%) SARI cases tested, 2057 (13%) had confirmed influenza, including 1427 (69%) aged <5 years. Multiple peaks of influenza occurred during summer, winter, and spring months. Influenza was associated with an estimated 115 and 142 SARI hospitalizations per 100 000 during 2010–2011 and 2011–2012 [including A(H3N2): 55 and 44 SARI hospitalizations per 100 000; pandemic A(H1N1): 33 SARI hospitalizations per 100 000 during 2010–2011; influenza B: 26 and 98 hospitalizations per 100 000], with the highest rate among children aged 6–11 months (3603 and 3805 hospitalizations per 100 000 during 2010–2011 and 2011–2012, respectively).ConclusionsIn central China, influenza A and B caused a substantial number of hospitalizations during multiple periods each year. Our findings strongly suggest that young children should be the highest priority group for annual influenza vaccination in China.

Clinical characteristics and factors associated with severe acute respiratory infection and influenza among children in Jingzhou, China

“…We used data from an active, population‐based surveillance system to assess epidemiological and clinical characteristics of hospitalized children with influenza. Our results are consistent with our recent disease burden estimation, which found that influenza was associated with an estimated 2021 SARI hospitalizations per 100 000 during 2010–2011 and 2349 per 100 000 during 2011–2012 among children aged <5 years10 and other studies outside China 12, 13. In this study, we observed the low birth weight and living with someone who smokes cigarettes in the household were independent risk factors for increased odds of influenza among children with SARI.…”

“…Surveillance was conducted in Jingzhou, Hubei Province, in three general hospitals and one pediatric hospital as previously described 10. All patients admitted to a surveillance hospital were screened by nurses and physicians for SARI and were considered eligible if the SARI case definition was met within 24 hours of hospital admission.…”

“…The highest influenza‐associated SARI rates occurred among children aged 6–11 months (3603 and 3805 hospitalizations per 100 000 during 2010–2011 and 2011–2012, respectively) and influenza‐associated SARI mostly affected children aged <5 years (2021 hospitalizations per 100 000 during 2010–2011 and 2349 per 100 000 during 2011–2012) 10. We conducted active SARI surveillance in central China to analyze the clinical and epidemiological characteristic of influenza‐associated SARI cases, including pneumonia, among pediatric patients aged <15 years.…”

Evolution of Influenza B Virus in Kuala Lumpur, Malaysia, between 1995 and 2008

“…Our data from Kuala Lumpur consist of laboratory-confirmed influenza, and we show that influenza B virus accounts for 26% of all influenza cases, suggesting a considerable national burden of disease, which is consistent with previously reported data indicating that influenza B virus accounted for 9 to 48% of confirmed influenza cases in Malaysia from 2006 to 2014 (4,6,20). Our study also showed an overwhelming burden of influenza B virus cases in young children, consistent with previous studies globally (3,(21)(22)(23)(24). Active coordination of surveillance efforts in sentinel clinics and hospitals, including the standardization of patient and epidemiological data collected, is needed to effectively monitor influenza disease dynamics in Malaysia.…”

Using a hospital admission survey to estimate the burden of influenza‐associated severe acute respiratory infection in one province of Cambodia—methods used and lessons learned

“…The World Health Organization's (WHO) global standards for influenza surveillance are used by many countries 8, 9, 10, 11. Severe acute respiratory infection (SARI) surveillance intends to capture hospitalized influenza‐associated severe respiratory illness cases and uses a case definition—either recommended by WHO or country‐specific—to identify severe presentations of influenza‐associated respiratory disease 12.…”