Shane Crotty returns to TWiV to review the immunology of COVID-19, including differences between infection and vaccination, increased breadth of antibodies after infection followed by vaccination, the roles of T cells, and whether booster vaccinations are needed.

The meteorologicomaniacs discuss the COVID-19 pandemic global death toll, effectiveness of vaccines against the delta variant, and how analysis of ancient viral DNA reveals that two pathogenic human viruses were brought into Mexico during the transatlantic slave trade.

In COVID-19 clinical update #78, Daniel Griffin covers ivermectin, convalescent plasma, disease in pregnant women, children and COVID, delta outbreak in an elementary school, validation of at-home antigen test, shedding in infected vaccinated people, mRNA vaccine antibody responses compared, AZD7442, fluvoxamine, one year outcomes in hospitalized patients, and post-vaccination disease.

The TWiV team explains what the Biden report on SARS-CoV-2 origins did not: evidence that the virus came from Nature, not a lab; and reveals new coronaviruses in rodents that inhabit populated areas in southern China.

In COVID-19 clinical update #77, Daniel Griffin discusses children becoming increasingly infected, virological characteristics of infections in vaccinated health care workers, transmission dynamics among close contacts, licensing of Pfizer mRNA vaccine, cost of hospitalization of unvaccinated patients, 29 times higher hospitalization rates in unvaccinated patients, boost in neutralizing antibody potency and breadth by third vaccine dose, and use of J&J vaccine as second dose.

Paul and Theodora return to TWiV to explain their research on determining the number of neutralizing epitopes on the SARS-CoV-2 spike that are recognized by antibodies, and engineering of a polymutant spike with twenty amino acid changes that demonstrates the high genetic barrier to escape from convalescent serum.

In COVID-19 clinical update #76, Daniel Griffin covers association of age and pediatric household transmission, rapid antigen testing in remote communities, shedding of infectious virus in vaccinated individuals, FDA amendment of mRNA vaccine EUA to allow a third dose, new vaccine mandate for NY state, full vaccination suppresses selection of variants, effectiveness of mRNA vaccines in nursing homes, sustained effectiveness of mRNA vaccines against hospitalization, and no benefit from early convalescent serum in high-risk outpatients.

In COVID-19 clinical update #75, Daniel Griffin reviews vaccine effectiveness against transmission, modeling effectiveness of daily antigen tests, updated CDC guidance for fully vaccinated, risk of infection with time after mRNA vaccination, reduced risk of infection after vaccination, therapeutic anticoagulants in critically ill patients, and 6 month outcomes in hospitalized patients.