TWiV 1207, hosted by Vincent Racaniello, Alan Dove, and Rich Condit, dedicates the episode to the late virologist Klaus Conzelmann. The main discussion covers two scientific papers: first, the extensive reverse zoonoses of the 2009 H1N1 pandemic influenza A virus in US swine, highlighting frequent human-to-pig transmission, subsequent antigenic drift within pig populations, and the potential for these evolved strains to re-emerge in humans, underscoring the critical need for continued surveillance. Second, a natural experiment from Wales demonstrates that the Zostavax shingles vaccine significantly reduces the incidence of dementia, suggesting a link between herpes virus reactivation and cognitive decline, possibly through both viral suppression and immunomodulatory effects. The hosts also address listener mail, debunking misinformation regarding avian flu vaccines and discussing the severe implications of proposed cuts to global health initiatives like the President's Malaria Initiative, emphasizing the broader political threats to science and public well-being.
Taking a Shot at Dementia: Unpacking Swine Flu Evolution and Vaccine Benefits
0:00 Introduction & Dedication: Hosts Vincent Racaniello, Alan Dove, and Rich Condit open the episode with a dedication to the late virologist Klaus Conzelmann, recognized for pioneering reverse genetics for negative-strand RNA viruses.
9:41 Swine Flu: A Potential Pandemic Source: The first paper discusses the reverse zoonoses of the 2009 H1N1 influenza A virus and its evolution in U.S. swine, emphasizing pigs as a crucial "mixing bowl" for influenza viruses.
10:39 Frequent Human-to-Swine Spillovers: The study identified 370 human-to-swine (H2S) spillovers of H1N1 from 2009-2021, primarily driven by high human flu burden and close contact on pig farms.
11:11 Antigenic Drift & Zoonotic Potential: H1N1 viruses circulating in pigs show significant antigenic drift, becoming genetically and antigenically different from human seasonal vaccine strains, posing a potential zoonotic threat.
11:24 Swine-to-Human Transmissions: There were 17 documented swine-to-human (S2H) transmission events since 2010, some involving children, demonstrating that pigs can reintroduce antigenically evolved viruses to humans.
27:31 COVID-19 Impact on Spillovers: H2S spillovers significantly reduced during the 2020-2021 COVID-19 pandemic due to decreased human activity, yet flu prevalence in pigs remained high, indicating internal circulation within swine populations.
37:54 Importance of Surveillance & Funding Concerns: The hosts stress the critical need for ongoing genomic and antigenic surveillance of influenza in swine as part of pandemic preparedness, expressing concern over current federal science funding cuts.
40:56 Zostavax Reduces Dementia Incidence: The second paper presents a "natural experiment" from Wales, where a birthdate-based eligibility cutoff for the Zostavax shingles vaccine revealed a significant reduction in new dementia diagnoses.
56:41 Significant Dementia Reduction & Mechanisms: Being eligible for the vaccine reduced shingles incidence by 20%, and remarkably, reduced new dementia diagnoses by 8.5% for the eligible group (20% for those actually vaccinated) over seven years. Proposed mechanisms include a reduction in varicella-zoster virus (VZV) reactivation and an independent immunomodulatory effect of the vaccine.
1:11:00 Public Health Implications: These findings provide strong evidence linking herpes virus reactivation to dementia, suggesting that shingles vaccination (preferably with the newer, more effective Shingrix vaccine) could be a simple, inexpensive intervention to significantly reduce dementia rates.
1:18:12 Listener Mail: RFK Jr. on Bird Flu Vaccines: Michael raises concerns about RFK Jr.'s misinformed claims that bird flu vaccines create "mutant factories" or that "letting the virus run through the flock" is a viable strategy; the hosts strongly refute these points.
1:26:35 President's Malaria Initiative Cuts: Brian shares disturbing details about proposed cuts to the President's Malaria Initiative, linking them to Elon Musk's alleged influence and estimating over 120,000 preventable deaths in Africa as a result.
1:34:03 Pick: Kidney Stones & Roller Coasters: Rich's pick highlights research suggesting that the vibrations from certain roller coasters (e.g., Thunder Mountain) may help facilitate the passing of small kidney stones.
1:39:10 Pick: Classic Sci-Fi Magazines: Alan's pick is for digital subscriptions to two long-standing science fiction publications, "Analog Science Fiction and Fact" and "Asimov's Science Fiction" magazines.
1:41:07 Pick: Science Under Threat: Vincent's pick is an Elife article, "Science Under Threat in the United States: How scientists and institutions should respond," which urges scientists to actively engage with the public and policymakers to defend science funding and integrity.
1:43:03 Listener Pick: Techdirt as a Democracy Blog: Charles's pick is a Techdirt article, "Why Tech Dirt Is Now A Democracy Blog," discussing the increasing intertwining of political interference with technology and scientific issues.
Summaries of Linked Articles:
Support science education at MicrobeTV: This link encourages listeners to contribute financially to MicrobeTV, as it relies on donations to fund its ad-free science education programs.
ASV 2025: This resource provides information about the American Society for Virology's 2025 meeting, including its location in Montreal, dates (July 14th-17th), program details, and important deadlines for registration and dependent care benefits.
Reverse zoonoses of 2009 H1N1 in US swine (PLoS Path): This paper demonstrates the significant and frequent transmission of the 2009 H1N1 pandemic influenza A virus from humans to U.S. swine populations. It reveals that these viruses undergo antigenic drift within pigs and can subsequently transmit back to humans, creating strains with zoonotic potential that may evade existing human vaccine-induced immunity, thus emphasizing the critical need for ongoing surveillance in swine.
Zostavax reduces dementia (Nature): This study, a natural experiment conducted in Wales, leveraged a birthdate-based eligibility cutoff for the Zostavax shingles vaccine. The research found that being eligible for, and especially receiving, the Zostavax vaccine significantly reduced the incidence of dementia diagnoses, suggesting a compelling link between herpes virus reactivation and the development of dementia, and proposing shingles vaccination as a potentially simple and inexpensive preventative measure.