Influenza and Influenza-Like Respiratory Virus Infections in Children During the 2019/20 Influenza Season and the COVID-19 Pandemic in Poland: Data from the National Influenza Centre, the Department of Influenza Research at the National Institute of Public Health, and 16 Voivodeship Sanitary and Epidemiological Stations

Abstract

Background This population study aimed to investigate influenza and influenza-like respiratory virus infections in children during the 2019/20 influenza season and the coronavirus disease 2019 (COVID-19) pandemic in Poland. Material/Methods This study analyzed data from the National Influenza Centre, the Department of Influenza Research at the National Institute of Public Health, and 16 Voivodeship Sanitary and Epidemiological Stations in Poland. Nose and throat swabs were obtained from children during the 2019/20 influenza season and the COVID-19 pandemic. Viral RNA detection was performed using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to diagnose influenza virus infection and viral subtypes. Results In the analyzed group, both cases of influenza A and B and infections with influenza-like viruses were confirmed. Among all cases caused by influenza viruses, influenza A was more frequent than B, with predominance of the A/H1N1/pdm09 subtype. The flu-like virus which infected most children was the human respiratory syncytial virus (RSV). The greatest number of cases with RSV was registered in the group of the youngest children (0–4 years). Conclusions This population study from Poland showed that during the COVID-19 pandemic, and during the winter influenza season of 2019/20, influenza and influenza-like viral infections in children showed some differences from previous influenza seasons. The findings highlight the importance of viral infection surveillance and influenza vaccination in the pediatric population.

Influenza and Influenza-Like Virus Infection in Children Under 14 Years of Age: An Investigation of 725 Cases in the 2021/2022 Influenza Epidemic Season in Poland

“…The presence of genetic material of influenza viruses was confirmed in 314 samples (45.5% of all tested samples). As in the epidemic season 2019/2020 [ 16 ], the vast majority of confirmed cases were influenza A infections – 272 cases (82.4% of all confirmed influenza infections), while 42 cases of influenza B were confirmed (12.7% of all confirmed influenza cases). Out of the confirmed influenza A cases, 114 were subtype A/H3N2/ infections.…”

“…The genetic material of the A/H1N1/pdm09 subtype was not found among the analyzed samples. It was different in the epidemic season 2019/2020 in that influenza A/H1N1/pdm09 viruses dominated among the types of influenza A viruses in this season [ 16 ]. The course of the 2020/2021 epidemic season was clearly different from the trend in the previous seasons.…”

“…This has been confirmed by the analyzed results of infection studies in children. As in the epidemic season 2019/2020 [ 16 ], the highest number of RSV infections was recorded, with 12 confirmed in children aged 0–14, which accounted for 80.0% of all influenza-like virus infections confirmed in the laboratory using the molecular biology method. In this age group, 3 cases of ADV infection were also confirmed.…”

“…This trend continued, to varying degrees, during the further waves of infections caused by the SARS-CoV-2 virus. Data from the European Center for Disease Prevention and Control (ECDC) showed a 99.5% decrease in confirmed influenza cases in the 2020/2021 epidemic season, across all age groups [ 15 , 16 ]. This was often due to the health policy of a given country.…”

Influenza – a problem still existing during the COVID-19 pandemic

“…Worldwide, there is a consensus that vaccinations, when available, are the best way to fight infectious diseases. However, despite many years of educational activities, publicizing the fact that vaccinations are the cheapest method of preventing post-influenza complications, only part of the population understands the purpose of this highly effective method of battling influenza [5][6][7][8][9][10][11].…”