Clinical Characteristics and Outcomes of Influenza A (H۳N۲/H۱N۱) Infection in Hospitalized Patients: A Report From Iran ۲۰۲۲-۲۰۲۳ Cold Season Outbreak

Background and Aim: Influenza A subtypes H۳N۲ and H۱N۱ are currently circulating among humans and are the main cause of seasonal epidemics in the temperate regions. The specific clinical features of influenza H۱N۱ and H۳N۲ infections have not been well evaluated in Iranian patients. Materials and Methods: An observational study was conducted on influenza-confirmed patients in Imam Khomeini Hospital Complex, Tehran, Iran from October ۲۰۲۲ to March ۲۰۲۳. The specimens tested positive for influenza using RT-PCR, were transported to the National Influenza Center (NIC) Laboratory for the typing identification. Different data, including demographics, comorbidities, length of hospitalization, outcomes, paraclinical features, and recent influenza vaccination were collected.   Results: A number of ۱۶۵ hospitalized patients with influenza infection were included: ۱۴۸ (۸۹.۷۰%) patients with H۳N۲ and ۱۷ (۱۰.۳۰%) with H۱N۱ infections. Among the patients ۵۵.۲۰% were male. The median age was ۴۹ years. The patients were symptomatic for an average of ۸ days. The most common symptoms were dyspnea (۶۰.۶%), fever (۵۸.۸%), and productive cough (۳۷.۶%). The median oxygen saturation was significantly lower in the H۳N۲ group (۹۱%–۸۱.۰, ۹۶.۰) than in the H۱N۱ group (۹۵%–۹۰.۰, ۹۷.۵) (P=۰.۰۲۹). The ground glass opacity (GGO) was the most common (۶۹.۱%) radiological pattern. Only one patient had received the influenza vaccine in the recent year.. The mortality rate (۱۹ patients: ۱۱.۵۵%) was associated with the cancer and liver diseases. Conclusion: Influenza A (H۳N۲ and H۱N۱) can be considered the outbreak cause in Iran in ۲۰۲۲–۲۰۲۳. The vaccination rate was very low and the mortality rate was high. Influenza vaccination is recommended to prevent death, especially in the patients with cancer.

کلیدواژه ها:

Clinical characteristics ، H۱N۱ ، H۳N۲ ، Influenza A ، Iran