Infectious Dose

What if the biggest misunderstandings about vaccine safety aren’t just about the science—but about how the system communicates it? In this updated guided tour of the Vaccine Safety Series, Heather maps the episodes that break down how vaccines are tested, monitored, and evaluated—and where communication and institutional failures have contributed to confusion and mistrust. This episode is designed to help you navigate the series—whether you’re new, revisiting key topics, or looking for the right episode to share with someone who has questions. Because understanding the science matters. But understanding the system matters too. Where to go next in the Vaccine Safety Series: 👉 Too Many Vaccines Too Soon? — Understanding the childhood vaccine schedule 👉 Expecting Protection — Vaccines during pregnancy 👉 The Wakefield Story — How misinformation took hold All citations in the blog posts at infectiousdose.com

When we talk about misinformation in public health, we usually imagine social media, conspiracy theories, or individuals misunderstanding science. But what if some of the most influential misinformation starts somewhere else? In this episode of Infectious Dose, Heather speaks with biomedical researcher Dr. Mark Ungrin about how scientific ideas move through institutional systems and why correcting errors can be surprisingly difficult once they become embedded in policy. They discuss: Why “human error” is often a misleading explanation for systemic failures How flawed studies can shape public health guidance Why institutional hierarchies can make correcting mistakes difficult The role of evidence-based medicine in shaping policy decisions Why transparency and accountability are essential for rebuilding public trust This conversation explores how misinformation can emerge from institutional processes themselves — and why understanding those systems is critical for responding more effectively to future pandemics and biological threats. 👉Dr. Ungrin's Talk: Science, Pseudoscience and Public Policy https://whn.global/science-pseudoscience-and-public-policy/ Transcript and sources at infectiousdose.com

Mpox isn’t just a headline from 2022. In this episode, we explore what scientists have learned about mpox since the global outbreak — from how the virus moves through the body to why its lesions can be so painful. We break down the biology of orthopoxviruses, the surprising role of human immune enzymes in shaping viral evolution, and the emergence of a new lineage known as clade Ib that researchers are watching closely. We also look at the bigger picture: wildlife reservoirs, genomic surveillance, vaccine strategies, and the global inequities that shape how outbreaks unfold. Mpox is not the most transmissible virus, nor the most lethal. But it offers a clear window into how zoonotic diseases evolve — and what happens when global attention fades while transmission continues. Topics covered: Mpox symptoms and pathogenesis How the virus spreads APOBEC3 mutations and viral evolution Clade Ib and emerging lineages Wildlife reservoirs and spillover Vaccines, antivirals, and public health response Global inequity in outbreak response See blog post at Infectiousdose.com for all citations.

What if attraction isn’t entirely yours? In this Outbreak After Dark episode, Heather, Kate, and Sam gather around the campfire to explore the parasites, fungi, and viruses that manipulate behavior in the name of survival. We’re talking: Toxoplasma gondii, the parasite that dampens rodents’ fear of cats The lancet liver fluke, which turns ants into grazing bait Ophiocordyceps, the real-life “zombie ant” fungus Baculoviruses that liquefy caterpillars from the treetops Hairworms that drive crickets into water Limb-altering trematodes that make frogs easier prey Insect viruses that disrupt courtship songs and pheromones And the global rise of antifungal-resistant Candidozyma (Candida) auris Then we turn the lens toward humans. Do gut microbes influence mood and attraction? Are pheromones real? What happens to your microbiome when you kiss someone? (Answer: about 80 million bacteria exchange in ten seconds.) This episode blends behavioral ecology, evolutionary strategy, fungal cautionary tales, and just enough snack-fueled chaos to keep it campfire-worthy. Because love isn’t always sweet. Sometimes it’s optimized. 🔥 Recipes for Parasite Punch, Symbiosis Spritz, Zombie Ant Tapenade Toasts, and Courtship Clusters are available on infectiousdose.com.

Nipah virus scares virologists, and for good reason. It infects endothelial cells and neurons. It can cause fatal encephalitis. It spreads from bats to humans, and sometimes between people. So why does it keep burning out? In this episode of Infectious Dose, we examine: Henipavirus biology and receptor usage (ephrin-B2/B3) Why neurotropism drives severity Why outbreaks are small but deadly Why R₀ remains low What would actually have to change for Nipah to go pandemic Why spillover keeps recurring in Kerala And why survival does not always mean full recovery This is a grounded look at pandemic thresholds — not panic headlines. Preparedness requires vigilance not hysteria. All citations in the companion blog post at infectiousdose.com

Syphilis is back—and it never really left. In this episode, we break down how a curable, preventable infection is resurging to cause a public health crisis across the U.S., and globally, especially among pregnant people and newborns. We unpack the science behind Treponema pallidum, the public health failures driving the crisis, and why trust in health systems is still broken—from Tuskegee to today. Plus: what you need to know about testing, treatment, and why a shot of penicillin makes all the difference. Sources at Infectiousdose.com

RSV is one of the most common respiratory viruses — and a leading cause of hospitalization in young children worldwide. In this solo episode, I explain what RSV is, how it spreads, and what illness typically looks like in babies, children, and adults. We cover when RSV can be managed at home, how to recognize breathing-related red flags, when to go to the ER or call an ambulance, and what supportive care actually helps. The episode also looks at the current RSV landscape, including rising cases in parts of the U.S. and new prevention tools — maternal vaccination and long-acting monoclonal antibodies — that are dramatically reducing severe RSV disease in infants. Clear, practical, and evidence-based. https://www.healthychildren.org/English/health-issues/conditions/chest-lungs/Pages/RSV-When-Its-More-Than-Just-a-Cold.aspx

Spiders inspire some of our deepest fears—but are they actually as dangerous as we think? In this Outbreak After Dark episode, Heather, Sam, and Kate dig into the real science behind spiders, venom, and so-called “spider bites,” separating evidence from exaggeration. Along the way, they unpack persistent myths, medical misattribution, and why spiders loom so large in outbreak lore—despite rarely being the culprit. Creepy? Yes. Deadly? Usually not. Welcome to Outbreak After Dark. Editor's Note: While this episode leans into humor and fear, spiders play an important ecological role and are rarely a danger to humans.  See companion blog post at infectiousdose.com for full transcript and references.

What are biological weapons—and what are they not? In this episode, Heather is joined by bio-risk consultant and biodefense researcher Conor Browne for a grounded, reality-based conversation about biological weapons, biodefense, and why public discourse around these topics so often goes wrong. Together, they unpack what actually defines a biological weapon, why intent and delivery matter, and how real historical programs differ from the conspiratorial narratives dominating social media and politics. They explore state and non-state capabilities, the real constraints involved in weaponization, and why most pathogens—even deadly ones—are not practical weapons. The conversation also tackles some of today’s most misunderstood ideas, including gain-of-function research, lab accidents versus deliberate release, dual-use research of concern (DURC), and the limits of attribution when outbreaks occur. Along the way, Conor explains why sloppy language isn’t just misleading—it can actively undermine public health and national security. This episode is a clear-eyed look at biological threats without fear-mongering, designed to replace panic with understanding and precision. Topics covered include: What actually qualifies as a biological weapon Why dangerous pathogens ≠ weapons Historical bioweapons programs and what they really looked like State vs. non-state actor capabilities Why lab accidents are not weapons Gain-of-function research, DURC, and political distortion How misinformation increases real biological risk

In this episode of Infectious Dose, Heather McSharry talks with Terry Virts—retired NASA astronaut, Air Force colonel, and candidate for Congress in Texas—about what happens when leadership ignores science. Drawing on his experience in aviation, spaceflight, and risk analysis, Terry discusses the real-world consequences of sidelining evidence in public health, climate, and emergency preparedness. The conversation covers COVID-era misinformation, vaccines, measles outbreaks, healthcare access in Texas, and the dismantling of scientific institutions. The episode also explores the parallels between spaceflight safety systems and high-containment biosafety labs—highlighting why science-based leadership isn’t optional when lives are on the line. 🔗 A full transcript PDF is available in the companion blog post at InfectiousDose.com. And Terry's campaign website is: https://www.terryvirts.com/ Follow Terry: @AstroTerry on Insta/Twitter/Bluesky and astro_terry on Threads Follow Heather: @pathogenscribe on Insta/Twitter/Bluesky/Threads

This week in “Seasonal, Not Safe,” we confront the truth about influenza in 2025–2026. It’s not “just the flu.” From the tragic stories of children lost to fast-moving infections, to the science of how influenza spreads, mutates, and turns deadly — this episode explores what’s really happening this season. We break down the rise of Subclade K, current global flu patterns, new U.S. vaccine policy controversies, and what makes the flu virus so evasive. Plus: how antiviral medications work, why vaccination rates are falling, and what’s coming next in the push for a universal flu vaccine.  All citations and updates available in companion blog post at infectiousdose.com

This New Year’s Eve episode isn’t about resolutions — it’s about a reset. In Still Curious: A New Year’s Reset (Without Resolutions), Heather reflects on a difficult year for science, public health, and trust, and makes the case for curiosity as a quieter, steadier way forward. Rather than focusing on optimism or big promises, this episode explores what it means to pause, to stay engaged without burning out, and to carry curiosity into the new year even when certainty feels loud. The episode closes with a gentle midnight mantra for anyone listening alone, early, or in need of calm at the turn of the year. Companion blog post at infectiousdose.com

This month’s Outbreak After Dark is a special holiday episode — and a heavier one. In A Consumption Christmas Carol , we reimagine Dickens’ classic ghost story through the real epidemic that haunted Victorian London: tuberculosis. Long before antibiotics, TB shaped daily life, art, poverty, and policy — romanticized in parlors, devastating in tenements, and deadly across all social classes. Guided by familiar spirits of past, present, and yet to come, we trace how tuberculosis was misunderstood, aestheticized, and ultimately revealed as an airborne infectious disease — one that remains among the world’s deadliest today. This episode blends historical storytelling, medical science, and reflection on why some diseases never truly stay in the past. Because this is a weightier story, we close the episode gathered by the fire for a post-Carol decompression — sharing snacks, drinks, behind-the-scenes thoughts, and space to process the history together. 🕯️ Outbreak After Dark is the after-hours storytelling series of Infectious Dose, where science, history, and a little gothic atmosphere meet.  This episode is an original reimagining inspired by Charles Dickens’ A Christmas Carol.

This episode was updated in March 2026 to explicitly frame the hepatitis B birth dose controversy through a systems-level lens — examining how evidence-based vaccine policy can be destabilized when institutional safeguards are removed, and why recognizing those failures is essential to restoring public trust. This episode unpacks everything you need to know about hepatitis B and the life-saving vaccine that helps prevent chronic liver disease and liver cancer later in life. From the biology of the virus to the science behind the birth dose, we explore how this vaccine works, why it’s given so early, and what’s at stake now that ideology is overriding evidence in U.S. vaccine policy. We also confront a dangerous shift in public health: the dismantling of expert-driven systems in favor of anti-vaccine rhetoric. The result isn’t just political—it’s personal. And it puts newborns at risk. In this episode: How hepatitis B infects the liver and evades the immune system Why newborns are uniquely vulnerable to chronic infection The history and science behind the universal birth dose What the ACIP overhaul means for public trust and public health Vaccine safety, ingredients, and long-term effectiveness Debunking the most common lies circulating on social media All citations are in the blog post for this episode at infectiousdose.com

This episode was updated in March 2026 to clarify that the analysis presented already reflects the systems-level framework used throughout this vaccine safety series — examining what the claim gets right, where institutional safeguards failed, and what evidence would actually be required to support the claims being made.  A leaked FDA memo sparked headlines claiming the COVID vaccine killed children — but the memo included no evidence, no data, and no scientific analysis. In today’s episode, Heather unpacks what the memo actually said, why experts across the field immediately rejected its conclusions, and how vaccine safety is truly evaluated. She explains the real risks of COVID in kids, from MIS-C to long COVID, and why misinformation from inside federal agencies threatens public trust and puts families at risk. Clear, compassionate, and evidence-driven, this episode gives parents the clarity they deserve. NOTE: All sources are cited in the blog post for this episode at infectiousdose.com

There’s more to your favorite winter rituals than nostalgia. In this episode, we dive into how centuries of winter traditions—across Europe, Asia, Africa, and the Americas—offered accidental protection against infectious diseases. From citrus in stockings to cloves in mulled wine, from kimchi to candlelight, we trace how ancient practices around food, air, warmth, and cleaning helped communities stay healthier in the harshest season. Learn how: Spices like cinnamon, ginger, and clove helped preserve food and reduce pathogens Fires, feasts, and fermentation doubled as primitive infection control Cleaning rituals and seasonal isolation slowed the spread of disease Modern public health can still draw lessons from these old traditions We also address how today’s world—sealed homes, global travel, and misinformation—has changed the game, and why clear science is more important than ever. 🎙️ Plus: a discussion of the recent HHS decision under Robert F. Kennedy Jr. to remove the statement “vaccines do not cause autism” from federal pages—and why this political move contradicts decades of scientific evidence. See the corresponding blog post at infectiousdose.com for all citations.

In this Outbreak After Dark episode, we revisit Thanksgiving’s origin story through the lens of infectious disease. Heather, Sam, and Kate dive into the epidemics that devastated Indigenous nations before the Pilgrims ever arrived, the microbial mismatches between Old World and New, and the narratives that still distort how we talk about “the First Thanksgiving.” It’s a campfire conversation that blends history, science, myth-busting, and respect for the communities whose histories were altered by plague long before the feast. All episode citations and recipes are in the blog post at infectiousdose.com

This week’s episode dives into the roots of the global antimicrobial resistance crisis. How did routine cuts, UTIs, and pneumonias become untreatable? What systems helped superbugs evolve — and why is the problem accelerating worldwide? We explore the science, the policies, the failures, and the future of drug-resistant microbes in A Prescription for Pestilence: The Global Spread of Antimicrobial Resistance. NOTE: All cited references are linked in the blog post for this episode at infectiousdose.com

Rift Valley fever is back — and it’s hitting harder than it has in years. In this episode, we trace the 2025 outbreak from Mauritania to Senegal, explore how the virus hides between rainy seasons, and reveal what scientists have learned from unexpected hotspots in Tanzania. From mosquitoes and livestock to people and policy, this is Rift Valley fever: when the rains bring life and loss. Don't miss today's (Nov 12, 2025) free webinar on RVF: The World Health Organization is hosting a free EPI-WIN webinar at 1pm CET, which is 7pm EST called “Rift Valley Fever and Community Protection: Gaps, Needs and Priorities,” and it brings together experts from WHO, Senegal, and Rwanda.

Headed into holiday travel season? This episode of Infectious Dose is your go-to guide for staying healthy on the road — without panic, shame, or disinfecting your entire row like you're filming a CSI episode. We talk practical prevention for planes, airports, road trips, and cruises, including how to avoid RSV, norovirus, and long COVID, what to pack in your health kit, why snacks matter, and how to travel with kids without losing your mind — or your mask. Smart tips, real science, and relatable chaos, all in one episode. NOTE: PDF Infection Prevention Travel Checklist available for listeners in the blog post at infectiousdose.com