Nonpharmaceutical interventions for COVID‐19 disrupt the dynamic balance between influenza A virus and human immunity

Abstract

During the COVID‐19 epidemic, nonpharmaceutical interventions (NPIs) blocked the transmission route of respiratory diseases. This study aimed to investigate the impact of NPIs on the influenza A virus (IAV) outbreak. The present study enrolled all children with respiratory tract infections who came to the Children's Hospital of Zhejiang University between January 2019 and July 2022. A direct immunofluorescence assay kit detected IAV. Virus isolation and Sanger sequencing were performed. From June to July 2022, in Hangzhou, China, the positive rate of IAV infection in children has increased rapidly, reaching 30.41%, and children over 3 years old are the main infected population, accounting for 75% of the total number of infected children. Influenza A (H3N2) viruses are representative strains during this period. In this outbreak, H3N2 was isolated from a cluster of its own and is highly homologous with A/South_Dakota/22/2022 (2021–2022 Northern Hemisphere). Between isolated influenza A (H3N2) viruses and A/South_Dakota/22/2022, the nucleotide homology of the HA gene ranged from 97.3% to 97.5%; the amino acid homology was 97%–97.2%, and the genetic distance of nucleotides ranged from 0.05 to 0.052. Compared with A/South_Dakota/22/2022, the isolated H3N2 showed S156H, N159Y, I160T, D186S, S198P, I48T, S53D, and K171N mutations. There was no variation in 13 key amino acid sites associated with neuraminidase inhibitor resistance in NA protein. Long‐term NPIs have significantly affected the evolution and transmission of the influenza virus and human immunity, breaking the dynamic balance between the IAV and human immunity.

Respiratory pathogen trends coinciding with the early public health response to limit transmission of SARS-Coronavirus-2.

“…Recently, in South Korea, a 120-1500-fold increase in specimens positive for in uenza A in children under 18 in June/July 2022 has been reported. 24 However, more recent Queensland in uenza trends show an above-5-year-average increase in cases in 2022, and an early surge in cases in 2023. 25 SARS-CoV-2 (omicron variant) is also now circulating widely in Queensland.…”

Bibliometric analysis of publication trends and topics of influenza‐related encephalopathy from 2000 to 2022

“…Besides, adverse events of the COVID‐19 vaccine, such as neurotoxic side effects, led to a decrease in people's willingness to vaccinate against the influenza vaccine 59–61 . Nonpharmaceutical interventions during the COVID‐19 epidemic may lower the body's immunity to the influenza A virus 62 . These may be likely influencing factors that need to be paid more attention to in future research on influenza‐related encephalopathy.…”

Epidemiological characteristics of common respiratory viruses among children in Hangzhou, China: comparison of COVID-19 before, during and after the pandemic

“…In March 2023, the number of people at the peak of Flu An infection (21,250) was higher than that in January-March 2019 before the epidemic (7,407), and Flu An infection rebounded and exceeded the historical level (2019), which appeared after most NPIs were relaxed. This may be because NPIs reduce the chance of contact with viruses, which leads to a decline in immunity 20 . Our results show that from January to February 2020, the number of people infected with RSV dropped sharply.…”