Hospital‐based influenza surveillance in Korea: Hospital‐based influenza morbidity and mortality study group

Abstract

Influenza epidemics occur annually with variations in size and severity. Hospital-based Influenza Morbidity & Mortality was established to monitor influenza epidemics and their severity, which is composed of two surveillance systems: emergency room-based and inpatient-based surveillance. Regarding emergency room-based surveillance, influenza-like illness index (influenza-like illness cases per 1,000 emergency room-visiting subjects), number of laboratory-confirmed cases and the distribution of influenza types were estimated weekly. Inpatient-based surveillance included monitoring for hospitalization, complications, and mortality. The emergency room influenza-like illness index correlated well with the number of laboratory-confirmed influenza cases, and showed a bimodal peak at Week 4 (179.2/1,000 emergency room visits) and Weeks 13-14 (169.6/1,000 emergency room visits) of 2012. Influenza A was the predominant strain during the first epidemic peak, while influenza B was isolated exclusively during the second peak. In 2011-2012 season, the mean admission rate of emergency room-visiting patients with influenza-like illness was 16.3% without any increase over the epidemic period. Among the hospitalized patients with influenza, 33.6% (41 out of 122 patients) were accompanied by complications, and pneumonia (28.7%, 35 out of 122 patients) was the most common. Most fatal cases were caused by influenza A (96.2%) after the first epidemic peak. In conclusion, Hospital-based Influenza Morbidity & Mortality was effective for monitoring the trends in circulating influenza activity concurrently with its severity. In the 2011-2012 season, the influenza epidemic persisted for a ≥ 5-month period, with a bimodal peak of influenza A and B in sequence. Overall, influenza A was more severe than influenza B.

Effect of the Influenza Virus Rapid Antigen Test on a Physician's Decision to Prescribe Antibiotics and on Patient Length of Stay in the Emergency Department

“…Chungbuk national university hospital, a 620-bed teaching hospital in Cheongju, Republic of Korea, began performing IVRAT in the ED during the 2011–2012 influenza season, when it became a participant in a sentinel hospital-based surveillance system for influenza (Hospital-based Influenza Morbidity and Mortality; HIMM) [15]. During the 2011–2012 season, all ILI patients who visited the ED were encouraged to provide consent for IVRAT.…”

“…At the same time, an additional swab specimen was taken and transported to the central HIMM laboratory. ILI was defined as the presence of fever (temperature ≥38°C, as measured in the ED) accompanied by at least one of the following respiratory symptoms (recorded by the attending physician): cough, sore throat, or rhinorrhea [15].…”

Prospective Cohort Study on the Effectiveness of Influenza and Pneumococcal Vaccines in Preventing Pneumonia Development and Hospitalization

“…In the ROK, a multicenter prospective cohort study was performed in 10 hospitals that had participated in a hospital-based influenza surveillance system (Hospital-Based Influenza Morbidity and Mortality [HIMM] system) since 2011 (10). During the 2013-2014 influenza season (1 November 2013 to 30 April 2014), emergency room (ER)-based surveillance was conducted by using ILI criteria; patients aged Ն19 years were enrolled.…”

“…During the 2013-2014 influenza season (1 November 2013 to 30 April 2014), emergency room (ER)-based surveillance was conducted by using ILI criteria; patients aged Ն19 years were enrolled. Clinical data and respiratory specimens were collected prospectively based on a standard protocol (10). A rapid influenza detection test was performed at the bedside, and nasal/throat swab specimens were transported to the central HIMM laboratory for multiplex respiratory viral PCR testing.…”

“…ILI was defined as sudden onset of fever (Ն38°C) accompanied by one or more respiratory symptoms, including cough, sore throat, or nasal symptoms (10). Clinical, radiological, and microbiological findings of all enrolled cases were evaluated to determine if patients fulfilled the following clinical and radiological CAP criteria: (i) acute pulmonary infiltrate consistent with pneumonia evident on chest radiographs within 48 h after admission, (ii) confirmatory findings on clinical examination, and (iii) acquisition of infection outside the hospital setting (11).…”