TWiV reviews a fatal Alaskapox case, MERS in Kenya, diagnostic tests for Nipah and Lassa diseases, HPV vaccination rates in the US, cases of measles in Arizona and Minnesota, hepatitis C virus-derived RNA circles in infected cells, and prevention of respiratory virus transmission by resident memory CD8+ T cells.

TWiV reviews a leaked CDC document on virulence and spread of the delta variant, and how anti-alphavirus antibodies that do not neutralize infection can nevertheless protect mice from disease.

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.

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.