Antigenic Drift of A/H3N2/Virus and Circulation of Influenza-Like Viruses During the 2014/2015 Influenza Season in Poland

Abstract

Morbidity rates of influenza could be greatly reduced due to vaccination. However, the virus is able to evolve through genetic mutations, which is why vaccines with updated composition are necessary every season. Their effectiveness depends on whether there is a good antigenic match between circulating viruses and vaccine strains. In Poland, the 2014/2015 influenza epidemic started in week 5 (January/February) of 2015 and continued until week 17 (April) of 2015. The influenza activity was moderate with the highest incidence of influence-like illness at week 10/2015 (March). During that season, antigenic drift of influenza virus A/H3N2/ occurred causing higher rates of A/H3N2/ infections. Among the 2416 tested specimens, 22.6 % of influenza cases were positive for A/H3N2/, while A/H1N1/pdm09 constituted 14.6 % cases. Influenza A viruses were detected in co-circulation with influenza B viruses; the latter amounted to 34.1 % of all influenza detections. Other detected causes of influenza-like illness consisted of respiratory syncytial virus (RSV), being predominant, and, sporadically, human coronavirus, parainfluenza 1-3, rhinovirus, and adenovirus. Despite low vaccine effectiveness of solely one component, A/H3N2/, the vaccine could mitigate or shorten the length of influenza infection and reduce the number of severe outcomes and mortality. Thus, vaccination against influenza remains the most effective way to prevent illness and possibly fatal outcomes.

The Activity of Influenza and Influenza-like Viruses in Individuals Aged over 14 in the 2015/2016 Influenza Season in Poland

“…The death as a sequelae of influenza was due usually to complications arising from the underlying chronic comorbidities, especially cardiovascular and respiratory disorders that ended up in fulminant pneumonia. The present findings of 40.2% of confirmed cases of influenza and influenza-like viruses in the 2015/2016 influenza season show a near doubling of laboratory confirmations compared with past seasons (Bednarska et al 2016b;Bednarska et al 2015). That result points to substantial improvements in infection surveillance and imbued nuances in the virological and epidemiological procedures despite a drastically low and inexplicably decreasing percentage of adult, mostly middle-aged, population getting vaccinated against influenza each epidemic season in Poland.…”

“…In both compared seasons, the highest incidence of influenza was reported in the age-groups of 45-64 and 26-44 years and the lowest one in the 15-24 years old persons ( Fig. 1) (Bednarska et al 2016b). Interestingly, the number of confirmed cases of influenza virus was the highest in the same age-groups of 45-64 and 26-44 years in the past 2013/2014 season (Bednarska et al 2015).…”

“…Improperly treated infections caused by influenza viruses can lead to complications and consequently to death. Therefore, it is important to confirm the presence of influenza virus in a short period of time, using molecular biology methods (Bednarska et al 2016b), which enables to apply antiviral drugs, i.e., neuraminidase inhibitors, soon after onset of symptoms (Fiore et al 2011;Brydak 2008).…”

Respiratory Infections with Particular Emphasis on Influenza Virus Activity in Persons Over 14 Years of Age in the Epidemic Season 2016/2017 in Poland

“…Comparing confirmed ILI infections among individuals aged over 14 in the epidemic seasons 2015/2016 and 2016/2017, the number of confirmations was at a comparable level (n ¼ 16 and n ¼ 22, respectively). In both seasons, also in 2014/2015, RSV infections were predominant (Kowalczyk et al 2017b;Bednarska et al 2016a).…”

Epidemic Influenza Seasons from 2008 to 2018 in Poland: A Focused Review of Virological Characteristics

“…For the entire European area, influenza type A virus predominance was confirmed in 69%, and type B virus in 31% (MRC 2014). Concerning type A virus, subtype A/H3N2/ (77%) predominated over A/H1N1/pdm09 (23%) (Bednarska et al 2016c). The number of confirmations of A/H3N2/ significantly exceeded that of A/H1N1/pdm09 in most countries of Southern Europe.…”