Evaluation of Antiviral Therapy for Influenza and Influenza-Like Diseases in Risk Groups

Background: Bacterial complication and prolonged course of influenza and influenza-like illnesses (ILI) are often observed among patients with risk factors for severe course of disease. The aim of study was to evaluate the efficacy of antiviral therapy with arbidol (umifenovir) in hospitalized patients with influenza and ILI who had risk factors for severe course of disease.

Methods: 3285 medical charts of patients with influenza and ILI have been retrospectively reviewed. Laboratory confirmation of disease was available in 31.0% patients; of these, influenza viruses were found in 60.7% samples (influenza A/H1N1 - 48.8%, A/H3N2 - 16.3%, influenza A subtype–10.6%, influenza B - in 24.3%, other respiratory viruses - 39.7%). Patients were divided into 2 groups depending on therapy. Antivirals were not administered to patients in the 1th group. 2th group of patients was treated with umifenovir from the first 24-48 hours after symptom onset. Patients in subgroups 1b (n = 155) and 2b (n = 628) had risk factors (children younger than 2 years old and adults over 65, pregnant women, people with chronic somatic diseases and obesity).

Results: Duration of fever and frequency of complications in patients without risk factors were significantly lower in 2a group versus 1a group: 2.86 ± 1.57 days and 3.76 ± 2.83 days, 13.1 ± 1.3% and 20.0 ± 3.2%, accordingly. Duration of fever and frequency of complications in patients with risk factors were significantly lower in 2b group versus 1b group: 3.0 ± 1.48 days and 4.1 ± 2.2 days, 9.9 ± 1.2% and 42.6 ± 3.6%, accordingly.

Conclusion: The efficacy of antiviral therapy was higher in patients with risk factors than in patients who are not at risk. In patients treated with umifenovir the duration of fever and frequency of complications were lower than in patients who did not receive antiviral therapy.