Human influenza viruses in South-East and East Asia: a systematic review of seasonal patterns, viral types/subtypes, and antiviral susceptibility pattern in the past two decades

Abstract

The study aims to evaluate influenza seasonality pattern and identify influenza viral types/subtype as well as their antiviral susceptibility pattern in South-East (SE) and East Asia (E-Asia) with the view of providing useful information for public health action. The study is a systematic review of existing literature involving the use of search engines such as Google Scholar, PubMed and EBSCOHOST. The search was conducted using a multi-stage approach which yielded 66 articles after screening for relevance to the subject using specific inclusion and exclusion criteria. A total of 60 articles were eventually analyzed and the findings were presented in tables and bar charts. The study showed that the influenza virus was more prevalent in the 6-20 years age group (SE: 53.3% and E-Asia: 44.8%) and also occurred commonly in the age of 61-90 years age group (SE: 15.6% and E-Asia: 24.1%). Seasonal peaks were reported more in the winter period with influenza A (H1N1) pdm09 (22.37%; 24.14%), seasonal influenza A (H1N1) (6.58%; 17.24%), A (H3N2) (11.84%; 17.24%), and influenza B Victoria/Yamagata (5.26%; 20.69%) being the predominant viral type/subtypes. The pathogenic avian influenza strains; AH5N1 (7.89%) and A (H7N9) (6.90%) was also reported in SE and E-Asia respectively. Oseltamivir (37.5%) and peramivir (37.04%) were the most frequently used anti-influenza agents in SE and E-Asia respectively. However, an H55Y+I436N combined mutation 4 (12.5%) and an H274Y amino acid substitution 5 (18.5%) in the neuraminidase gene of influenza A (H1N1) pdm09 was associated with decreased sensitivity to neuraminidase inhibitors. The study has shown that influenza A (H1N1) pandemic and seasonal strain, A (H3N2), and B Victoria/Yamagata remains the predominant circulating virus in SE and E-Asia. However, the dynamic antigenic and genetic evolution of the virus calls for more frequent surveillance in the region.

What are the environmental factors that affect respiratory viral pathogen transmission and outcomes? A scoping review of the published literature

“…There are no up-to-date systematic reviews, using comprehensive literature searches and assessment of the risk of bias in included studies, that assess environmental effects on respiratory virus transmission as a whole. Recent systematic reviews have focused on COVID-19 and single environmental factors, such as climate variables and seasonality (4,5), temperature and humidity (6), with one systematic review focusing on seasonal patterns of influenza (7). However, there was no review collating all the published evidence on the effect of environmental factors on respiratory virus transmission.…”