Influenza presents a considerable disease burden, particularly among adults over 65 years old. In this population, the disease is associated with high rates of infection, hospitalization, and mortality. The objective of this study was to assess the impact of influenza on older adults and to evaluate the effectiveness of influenza vaccines within this demographic. A literature search was conducted using PubMed to identify relevant English-language studies published from January 2000 to January 2024. The analysis indicated that influenza-related hospitalization rates (ranging from 10.1 to 308.3 per 100,000 persons) and all-cause excess mortality rates (1.1 to 228.2 per 100,000 persons) were notably high in older adults, although these rates varied over time and by location. Hospitalization rates due to influenza increased considerably after the age of 50 years, with the highest rates observed in individuals aged 85 years and older. Excess mortality attributable to influenza also rose with age, with rates between 17.9 and 223.5 per 100,000 persons in those over 75 years old. The effectiveness of influenza vaccines in preventing severe infections requiring hospitalization was found to be only 37% in individuals aged 65 years and older. The unadjuvanted, standard-dose influenza vaccine had an estimated effectiveness of just 25% against laboratory-confirmed influenza and between 37% and 43.7% in preventing hospitalizations. Therefore, considering the substantial burden of influenza and the limited efficacy of standard vaccines, the use of highly immunogenic influenza vaccines should be prioritized for older adults.
Citations
During the COVID-19 pandemic, the first seasonal influenza epidemic was declared in the 37th week of 2022 in Korea and has continued through the winter of 2023–2024. However, this finding has not been observed in the United States and Europe. The present study aimed to determine whether the prolonged influenza epidemic in Korea from 2022 to 2023 was caused by using a different influenza epidemic threshold compared to the thresholds used in the United States and Europe.
Korea, the United States, and Europe use different methods to set seasonal influenza epidemic thresholds. First, we calculated the influenza epidemic thresholds for influenza seasons using the different methods of those three regions. Using these epidemic thresholds, we then compared the duration of influenza epidemics for the most recent three influenza seasons.
The epidemic thresholds estimated by the Korean method were lower than those by the other methods, and the epidemic periods defined using the Korean threshold were estimated to be longer than those defined by the other regions’ thresholds.
A low influenza epidemic threshold may have contributed to the prolonged influenza epidemic in Korea, which was declared in 2022 and has continued until late 2023. A more reliable epidemic threshold for seasonal influenza surveillance needs to be established in Korea.
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Oseltamivir has been used as a worldwide preparation for treatment of influenza A and B including H1N1. Gastrointestinal discomforts as like nausea, vomiting are commonly reported but acute hemorrhagic colitis is a very rare adverse effect. We report a case of a 17-year-old male who showed abdominal pain, diarrhea and hematochezia after the second administration of oseltamivir. Computed tomography revealed continuous, circumferential and edematous wall thickening involving ascending to descending colon with pericolic infiltration. Colonoscopic examination revealed diffuse mucosal edema, congestion and friability, suggesting hemorrhagic colitis. Histopathological examination showed ischemia and focal loss of the crypts. It also showed hyalinization and minimal inflammatory cell infiltration in the lamina propria, consistent with acute to subacute ischemic colitis. This report is the first case of oseltamivir-related ischemic colitis proved by both endoscopic examination and pathologic findings in the patient who had no risk factor of ischemic colitis in Korea.
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Influenza virus infection is a common respiratory disease in children. Renal complications of influenza infection were not commonly encountered until the 2009 H1N1 influenza pandemic, when acute kidney injury (AKI) frequently developed in severely ill patients. Kawasaki disease (KD) is another rare association in pandemic influenza virus infections. There are some reports about KD coincident with influenza A H1N1/09 infection. However, simultaneous AKI and KD in influenza A or B virus infections have never been reported. Herein, we report the first case of influenza B virus infection that initially presented as AKI but was subsequently diagnosed as atypical KD.