Co-infection with Influenza Viruses and Influenza-Like Virus During the 2015/2016 Epidemic Season

Abstract

Concerning viral infection of the respiratory system, a single virus can cause a variety of clinical symptoms and the same set of symptoms can be caused by different viruses. Moreover, infection is often caused by a combination of viruses acting at the same time. The present study demonstrates, using multiplex RT-PCR and real-time qRT-PCR, that in the 2015/2016 influenza season, co-infections were confirmed in patients aged 1 month to 90 years. We found 73 co-infections involving influenza viruses, 17 involving influenza viruses and influenza-like viruses, and six involving influenza-like viruses. The first type of co-infections above mentioned was the most common, amounting to 51 cases, with type A and B viruses occurring simultaneously. There also were four cases of co-infections with influenza virus A/H1N1/pdm09 and A/H1N1/ subtypes and two cases with A/H1N1/pdm09 and A/H3N2/ subtypes. The 2015/2016 epidemic season was characterized by a higher number of confirmed co-infections compared with the previous seasons. Infections by more than one respiratory virus were most often found in children and in individuals aged over 65.

A case of reassortant seasonal influenza A(H1N2) virus, Denmark, April 2019

“…Circulation of A(H1N2) viruses genetically similar to the Chinese cases was observed globally in humans in 2000 to 2003 [6]. Dual infections with influenza A subtypes are not unusual [7,8], and pose a risk for reassortment events and the occurrence of new viruses. A special concern is the risk of reassortment events between seasonal and zoonotic viruses, which could result in viruses with pandemic potential [9].…”

Infections with Influenza A/H3N2/ Subtype in Poland in the 2016/2017 Epidemic Season

“…We found that the A/H3N2/ subtype of influenza virus predominated in Poland during the 2016/2017 season. This finding contrasted with the preceding 2015/2016 season when, although somehow fewer samples were tested, the A/H1N1/pdm09 subtype predominated (Cieślak et al 2017;Kowalczyk et al 2017;Szymański et al 2017a). However, the A/H3N2/ also was a leading subtype in the 2014/2015 season, although it circulated together with the A/H1N1/ pdm09 subtype (Bednarska et al 2016).…”

“…In the 2016/2017 season in Poland, there were 11 coinfections of the A/H3N2/subtype with other influenza and influenza-like viruses, particularly found in the elderly and young children (Table 1). In contrast, in the preceding 2015/ 2017 season, the presence of the A/H3N2/subtype was not confirmed in any of the coinfections (Szymański et al 2017a). For comparison, in the past 2014/2015 and 2013/2014 seasons, there were only two and four coinfections recorded with this subtype, respectively, in children up to 14 years (Hallmann-Szelińska et al 2016;Bednarska et al 2015).…”

Back to the Future for Influenza Preimmunity—Looking Back at Influenza Virus History to Infer the Outcome of Future Infections

“…This study provides evidence that the heterotypic infection-reinfection occurs at an observable frequency and can lead to severe disease without cross-protection. Moreover, other studies have showed prominent co-infections of influenza A and influenza B viruses [ 104 ]. Further study is needed to understand the mechanisms of immune activation or suppression during sequential heterotypic and co-infections of two influenza virus types.…”