Non-pharmaceutical interventions reduced the incidence and exacerbation of allergic diseases in children during the COVID-19 pandemic

Epidemiological and genetic characteristics of norovirus in Hangzhou, China, in the postepidemic era

OBJECTIVE

Norovirus (NoV) is an important human pathogen that can cause severe gastroenteritis in vulnerable populations. This study aimed to analyze the epidemiological and genetic characteristics of 2021-2023 NoV in Hangzhou, China.

METHODS

This study enrolled patients aged 0-18 years who underwent NoV RNA detection in the hospital between January 2021 and October 2023 and analyzed the epidemiological characteristics of NoV. Polymerase chain reaction (PCR) was used to detect NoV RNA. Subtype classification and whole-genome sequencing were performed.

RESULTS

There was a high prevalence of NoV infection in 2023, with NoV-positive samples accounting for 63.10 % of the total number of positive samples collected during the three-year period. The prevalence was abnormally high in summer, and the number of positive samples accounted for 48.20 % of the total positive samples for the whole year, which was much greater than the level in the same period in previous years (2023, 48.20% vs 2021, 13.66% vs 2022, 15.21 %). The GⅡ.4 subtype played a leading role, followed by increased mixed infection with GⅠ.5 and GⅡ.4. Whole-genome sequencing results suggested that GII.P16-GⅡ.4 had R297H and D372N key locus mutations. The evolutionary rate was 4.29 × 10-3 for the RdRp gene and 4.84 × 10-3 for the VP1 gene. The RdRp gene and VP1 gene of NoV GII.P16-GⅡ.4 have undergone rapid population evolution during the COVID-19 epidemic.

CONCLUSION

In the summer of 2023, an abnormally high incidence of NoV appeared in Hangzhou, China. The major epidemic strain GII.P16-GⅡ.4 showed a certain range of gene mutations and a fast evolutionary rate.

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

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.