Ron Fouchier explains why increased transmission of SARS-CoV-2-variants has not been demonstrated, and their ability to displace ancestral variants is due to greater fitness, much like influenza virus antigenic variation leads to better fitness and replacement of previously circulating variants.

TWiV returns to the 2012 brouhaha over transmission experiments with avian H5N1 influenza virus, re-examines the claim of SARS-CoV-2 RNA integration into human DNA, and reviews the engineering and testing of a genetically stable version of the attenuated type 2 Sabin poliovirus vaccine.

In COVID-19 clinical update #62, Daniel Griffin covers outdoor transmission of the virus, safe use of NSAIDS, expansion of Pfizer/BioNTech vaccine to include 12-15 year olds, post-disease Mucormycosis, and hydroxychloroquine treatment associated with increased mortality.

TWiV reviews the latest data on the UK variant of SARS-CoV-2, including some properties of the variant and why it is being closely studied, development of liver cancer in a participant in a adenovirus-associated virus gene therapy trial, and answers to listener questions.

On this episode, TWiV makes Bloomberg Business News 2020 Jealousy List, crushing of CDC revealed by insiders, seasonal influenza during the COVID-19 pandemic, FDA briefing documents from Moderna, and three-quarters attack rate of SARS-CoV-2 during an unmitigated epidemic in Brazil.

Daniel Griffin provides a clinical report on COVID-19, Slovlakia’s plan to test all adults for SARS-CoV-2 infection, viral variants arising in Danish mink and their potential threat to humans, why it is unethical to carry out challenge trials, Nipah virus dynamics in bats and spillovers into humans, and direct cardiac damage by spike-mediated cardiomyocyte fusion.