1.Introduction
Influenza is a contagious respiratory disease that is widespread across
the globe. Despite advances in medical technology, influenza causes
considerable hospitalizations and mortality1,2. H1N1
is a subtype of influenza A virus that leads to respiratory infections
and has caused two pandemics over the past 102
years3,4. The most recent pandemic of H1N1 influenza
occurred in 2009 and affected 60.8 million people, resulting in 284,000
deaths worldwide5,6.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now
spread to most countries, with WHO declaring a COVID-19 pandemic on
March 1, 20207. As of June 24, 2020, more than nine
million confirmed cases and 473,061 deaths had been reported
globally8. The outbreak of COVID-19 began in December
2019, which also corresponded with the flu season in China and the
United States9,10, the management of the disease was
often complicated by the diversity in “influenza-like” clinical
manifestations. Hence, differentiating the clinical impact of SARS-CoV-2
and H1N1 virus-infection will facilitate rational arrangements for
implementation of COVID-19 prevention and treatment strategies. Previous
studies have only compared the general epidemiological and clinical
presentation of patients infected SARS-CoV-2 and H1N1
virus11-16. However, few studies have been performed
to compare the severity and clinical outcome of these two types of
infection.
Recently, influenza A(H1N1)pdm09
was reported as a common co-pathogen in COVID-19
patients17, and the viral co-infection is proved to be
associated with more adverse clinical outcomes18-20.
The data on the clinical characteristics and outcomes of patients
mix-infected with SARS-CoV-2 and H1N1 are scarce, but are of paramount
importance to the development of efficacious interventions and
protective measures. Therefore, to facilitate efforts, both in China and
globally, we report the clinical features, severity and outcome of
patients with laboratory-confirmed H1N1, SAR-CoV-2 infection and
co-infection with both viruses.