Background In the current COVID-19 pandemic, COVID-19 viral respiratory symptoms have been confused with other viral respiratory infections such as influenza. Given that both viruses cause respiratory diseases, there are important differences between these two viruses in terms of how they are spread, controlled and treated. Due to these differences, a definitive diagnosis of each infection has important implications for the public health measures that can be implemented in response to the treatment of each virus.
Method In this cross-sectional retrospective study from 4th September 2020 to 5th December 2020 (time period of influenza outbreak in Iran, a total of 455 Severe Acute Respiratory Infections (SARI) patients were included. Two nasopharyngeal and one oropharyngeal throat swab samples were collected from all participants and evaluated for COVID-19 by real-time reverse transcriptase–polymerase-chain-reaction (RT-PCR) assay using the E-Gene specific primers/FAM probe and S Gene primers/ROX probe (Covitech, Iran) for SARS-CoV-2. Due to the concurrence of the study in autumn and the history of influenza outbreak at this time in Iran. Nasopharyngeal samples were collected and tested for influenza viruses A (H1N1, H3N2, seasonal flu), and Influenza B by one step qRT-PCR Master Mix (Invitrogen, United States) and AG synthesis probe and primers (Metabion, Germany) for Influenza A (H1N1, H3N2, seasonal flu) and B.
Results In this study, 455 patients with SARI were hospitalized during September to December 2020. 203(44.61%) were infected with SARS-COV-2 and of these patients, one patient was positive for both COVID-19 and Influenza. The mean age was estimated 54.93 ± 17.00 and 50.65 ± 17.71 in COVID-19 and non-COVID-19 groups, respectively which was significantly different (P < 0.001). Sex distribution between two groups showed that most of COVID-19 patients were male, this is in contrast with the COVID-19 negative group, in which most of patients were female and these differences were statistically significant. (P = 0.057). Clinical outcomes of patients with diagnosed SARI were measured. The main parameters were discharge from ICU and death during hospital admission. There was no significant difference between the number of patients discharge from ICU who were COVID positive or COVID negative. In addition, there was no significant difference between the number of patients who died who were COVID positive or COVID negative.
Conclusion The decline in Influenza incidence and coinfection with COVID-19 in comparison to previous years appears to be significant due to its concurrence with the COVID19 pandemic and general population awareness on observing the instructions for personal respiratory protection e.g mask-wearing, hand washing, self-isolation and public health measures. Therefore, routine testing and empirical treatment for suspected influenza coinfection in COVID-19 patients is not recommended.