Seasonal and pandemic influenza: 100 years of progress, still much to learn

Abstract

Influenza viruses are highly transmissible, both within and between host species. The severity of the disease they cause is highly variable, from the mild and inapparent through to the devastating and fatal. The unpredictability of epidemic and pandemic outbreaks is accompanied but the predictability of seasonal disease in wide areas of the Globe, providing an inexorable toll on human health and survival. Although there have been great improvements in understanding influenza viruses and the disease that they cause, our knowledge of the effects they have on the host and the ways that the host immune system responds continues to develop. This review highlights the importance of the mucosa in defence against infection and in understanding the pathogenesis of disease. Although vaccines have been available for many decades, they remain suboptimal in needing constant redesign and in only providing short-term protection. There are real prospects for improvement in treatment and prevention of influenza soon, based on deeper knowledge of how the virus transmits, replicates and triggers immune defences at the mucosal surface.

100 years of influenza research seen through the lens of Covid-19

“…Coinfections contribute significantly to morbidity and mortality in influenza. 1 Early data from China suggested co-infection in as many as 50% of deceased SARS-CoV-2 patients, 10 while other reports in milder disease suggest co-infection in 10% or less. Details on pathogens associated with co-infection are limited, but Chen et al described complex infections with a combination of Gram-negative pathogens identified, as well as fungi in a few cases.…”

“…Dunning et al provide a comprehensive overview of current knowledge regarding seasonal influenza, with a detailed description on how the immunology of influenza has shaped the current standard of therapy and prevention. 1 This review was written in the period before the world was confronted with the SARS-CoV-2 outbreak, which for many might feel a long time ago, though in reality is only 2-3 months in the past. We now live in a very different world where a novel virus has redefined how we experience essential elements of modern life ranging from work and education to travel and recreation.…”

“…This knowledge has helped us to develop antiviral therapies and vaccination strategies. 1 Yet we still face challenges identifying those patients who develop critical illness and bacterial super-infection as the authors high-light. There can also be surprises though: the author's own data shows that patients with asthma were less likely to present with severe pulmonary or systemic disease when exposed to H1N1pdm09.…”

“…There can also be surprises though: the author's own data shows that patients with asthma were less likely to present with severe pulmonary or systemic disease when exposed to H1N1pdm09. 1 When faced with a brand new virus like SARS-CoV-2 rapidly emerging in the human population, we have a much more limited knowledge base to work with, leaving us at a significant disadvantage. We rapidly must understand the origin, genetic variation and epidemiological characteristics of the new virus.…”

“…Bacterial vaccines, specifically those directed against the pneumococcus, are a cornerstone of prevention of influenza-related morbidity and mortality especially in vulnerable groups, at times of seasonal or pandemic influenza. 1 Research is needed to establish if management of (mixed) bacterial infections over the course of disease is also important for successful treatment of Covid-19, so we can consider these alternative preventive strategies.…”