Temporal dynamics of Human mastadenovirus species in cases of respiratory illness in southern Brazil

Low circulation of Influenza A and coinfection with SARS-CoV-2 among other respiratory viruses during the COVID-19 pandemic in a region of southern Brazil

With the arrival of coronavirus disease 2019 (COVID-19) in Brazil in February 2020, several preventive measures were taken by the population aiming to avoid severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection including the use of masks, social distancing, and frequent hand washing then, these measures may have contributed to preventing infection also by other respiratory viruses. Our goal was to determine the frequencies of Influenza A and B viruses (FLUAV/FLUBV), human mastadenovirus C (HAdV-C), Enterovirus 68 (EV-68), and rhinovirus (RV) besides SARS-CoV-2 among hospitalized patients suspect of COVID-19 with cases of acute respiratory disease syndrome (ARDS) in the period of March to December 2020 and to detect possible coinfections among them. Nucleic acid detection was performed using reverse-transcription quantitative polymerase chain reaction (RT-qPCR) in respiratory samples using naso-oropharyngeal swabs and bronchoalveolar lavage. A total of 418 samples of the 987 analyzed (42.3%) were positive for SARS-CoV-2, 16 (1.62%) samples were positive for FLUAV, no sample was positive for FLUBV or EV-68, 67 (6.78%) samples were positive for HAdV-C, 55 samples were positive for RV 1/2 (26.3%) and 37 for RV 2/2 (13.6%). Coinfections were also detected, including a triple coinfection with SARS-CoV-2, FLUAV, and HAdV-C. In the present work, a very low frequency of FLUV was reported among hospitalized patients with ARDS compared to the past years, probably due to preventive measures taken to avoid COVID-19 and the high influenza vaccination coverage in the region in which this study was performed.

Epidemiology of human adenovirus associated with respiratory infection in southern Brazil

Human adenoviruses (HAdVs) are associated with respiratory infection in the human population worldwide, but HAdV is underreported and less studied than other respiratory viruses. We investigated HAdV in patients with respiratory infection in Rio Grande do Sul (RS), Brazil, between 2004 and 2018. The frequency and seasonality of HAdV, clinical symptoms and underlying diseases were analysed. Respiratory samples from outpatients with acute respiratory illness (ARI) who attended sentinel units and from inpatients with severe acute respiratory infection (SARI) were collected for HAdV detection by immunofluorescence assay; demographic and clinical data were analysed. In total, 43,514 cases of respiratory infection were analysed, of which 8,901 were ARI (20.5%), and 34,613 (79.5%) were SARI. Respiratory viruses were detected in 35.8% of the cases. The frequency of HAdV in relation to respiratory viruses was 2.8%. HAdV circulated year-round, with higher frequency during winter and early spring; increases in the average monthly temperature were associated with decreases in HAdV infections (p = 0.013). Most hospitalized patients with HAdV were male (p = 0.003). HAdV infection showed association with age (p < 0.001), and children between 1 and 5 years old accounted for 30.8% of the outpatients, whereas among cases of SARI, 88.2% were paediatric patients. Among inpatients with HAdV, 3% died, and of these, the majority had at least one underlying condition, such as cardiopathy and immunosuppression. HAdV infection of the respiratory tract causes morbidity and mortality, and individuals with heart diseases and the immunocompromised are at higher risk of fatality.