Influenza A(H3N2) has been a major cause of seasonal influenza in humans since 1968, and has evolved by antigenic drift under the constantly changing human herd immunity. Increasing evidence suggests that the antigenic change occasionally occurred concomitant with the alterations of the N-glycosylation site profile and hemagglutination activity of the virion surface protein hemagglutinin (HA). ...

Swine influenza is an acute respiratory disease caused by type A influenza viruses. Before 1998, swine influenza virus isolates in the United States were mainly of the classical H1N1 lineage. Since then, phylogenetically distinct reassortant H3N2 viruses have been identified as respiratory pathogens in pigs on U.S. farms. The H3N2 viruses presently circulating in the U.S. swine population are t...

The H3N8 virus and the H3N2 virus are the main subtypes of canine influenza virus (CIV). H3N8 CIV mainly circulates in America, and H3N2 CIV mainly circulates in Asia. However, there was an outbreak of the Asian H3N2 virus in the United States (US) in 2015. Thus, it is important to evaluate the presence of subtype H3N8 virus in dogs in China. From May 2015 to November 2015, 600 sera from pet do...

We define a new parameter to quantify the antigenic distance between two H3N2 influenza strains: we use this parameter to measure antigenic distance between circulating H3N2 strains and the closest vaccine component of the influenza vaccine. For the data between 1971 and 2004, the measure of antigenic distance correlates better with efficacy in humans of the H3N2 influenza A annual vaccine than...

Annual vaccination against seasonal influenza viruses is recommended for certain individuals that have a high risk for complications resulting from infection with these viruses. Recently it was recommended in a number of countries including the USA to vaccinate all healthy children between 6 and 59 months of age as well. However, vaccination of immunologically naïve subjects against seasonal in...

A key priority in infectious disease research is to understand the ecological and evolutionary drivers of viral diseases from data on disease incidence as well as viral genetic and antigenic variation. We propose using a simulation-based, Bayesian method known as Approximate Bayesian Computation (ABC) to fit and assess phylodynamic models that simulate pathogen evolution and ecology against sum...

INTRODUCTION Comparisons of the characteristics between the influenza A (H1N1) pdm09 and common seasonal influenza are important for both clinical management and epidemiological studies. However, the differences between pandemic and seasonal influenza during the post-pandemic period are poorly understood. OBJECTIVES The aim of our research was to investigate clinical and immune response diffe...

BACKGROUND Vietnam is currently developing domestic capability to manufacture influenza vaccines but information on the genetic and antigenic characteristics of locally circulating seasonal influenza viruses is limited. To assess the relevance of WHO recommended vaccine strains to the situation in Vietnam, we analyzed the genetic relatedness of the hemagglutinin (HA) gene of seasonal influenza ...

BACKGROUND Oseltamivir-resistant mutants with higher drug resistance rates and low trans-mission fitness costs have not accounted for influenza (sub)type viruses. Predicting the impacts of neuraminidase inhibitor therapy on infection rates and transmission of drug-resistant viral strains requires further investigation. OBJECTIVES The purpose of this study was to assess the potential risk of o...

The 2011/12 season was characterised by unusually late influenza A (H3N2) activity in the United Kingdom (UK). We measured vaccine effectiveness (VE) of the 2011/12 trivalent seasonal influenza vaccine (TIV) in a test-negative case–control study in primary care. Overall VE against confirmed influenza A (H3N2) infection, adjusted for age, surveillance scheme and month, was 23% (95% confidence in...