Abstract
The expansion and standardization of clinical trials, as well as the use of sensitive and specific molecular diagnostics methods, provide new information on the age-specific roles of influenza and other respiratory viruses in development of severe acute respiratory infections (SARI). Here, we present the results of the multicenter hospital-based study aimed to detect age-specific impact of influenza and other respiratory viruses (ORV). The 2018–2019 influenza season in Russia was characterized by co-circulation of influenza A(H1N1)pdm09 and A(H3N2) virus subtypes which were detected among hospitalized patients with SARI in 19.3% and 16.4%, respectively. RSV dominated among ORV (15.1% of total cases and 26.8% in infants aged ≤ 2 years). The most significant SARI agents in intensive care units were RSV and influenza A(H1N1)pdm09 virus, (37.3% and 25.4%, respectively, of PCR-positive cases). Hyperthermia was the most frequently registered symptom for influenza cases. In contrast, hypoxia, decreased blood O2 concentration, and dyspnea were registered more often in RSV, rhinovirus, and metapneumovirus infection in young children. Influenza vaccine effectiveness (IVE) against hospitalization of patients with PCR-confirmed influenza was evaluated using test-negative case–control design. IVE for children and adults was estimated to be 57.0% and 62.0%, respectively. Subtype specific IVE was higher against influenza A(H1N1)pdm09, compared to influenza A(H3N2) (60.3% and 45.8%, respectively). This correlates with delayed antigenic drift of the influenza A(H1N1)pdm09 virus and genetic heterogeneity of the influenza A(H3N2) population. These studies demonstrate the need to improve seasonal influenza prevention and control in all countries as states by the WHO Global Influenza Strategy for 2019–2030 initiative.
Highlights
Building on its 70 years of global health leadership, the WHO developed the Global Influenza Strategy for 2019–2030 to enhance global and national pandemic preparedness, to combat the ongoing threat of zoonotic influenza, and to improve seasonal influenza prevention and control in all countries [1]
Positive PCR results for influenza were obtained in 1108 (36.2%) cases from 3057 patients included in the study; other respiratory viruses (ORV) were detected in 1169 (38.2%) patients, and 973 (31.8%) patients were negative for the respiratory viruses tested
A total of 709 (64%) cases of laboratory-confirmed influenza (LCI) were registered among children, and 399 (36%) cases were in adults
Summary
Building on its 70 years of global health leadership, the WHO developed the Global Influenza Strategy for 2019–2030 to enhance global and national pandemic preparedness, to combat the ongoing threat of zoonotic influenza, and to improve seasonal influenza prevention and control in all countries [1]. Other studies have shown that up to 50% of pneumonia cases are linked to respiratory viruses, and up to 45% of pneumonia cases in children show evidence of viral–bacterial co-infection [1]. The newly established Global Influenza Hospital Surveillance Net (GIHSN) has opened additional opportunities for strengthening of the clinical and laboratory surveillance for influenza and other respiratory viruses. The system provides opportunities for determination of age-related features of severe acute respiratory infection (SARI) etiology, including: illness severity, with identification of dominating agents; comorbidities leading to hospitalization; and assessment of risk factors on the clinical and virological levels. The GIHSN system enables an objective assessment of the effectiveness of influenza vaccines and antivirals in preventing hospitalization [4,5,6]. Subtle analysis of the antigenic and genetic structure of influenza viruses makes it possible to determine whether the viruses circulating in a specific season or country match the strains introduced into the vaccine composition
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