In the Season one finale of our show, hosts Dr. Vivian Vega and Dr. Jackie Sherbuk reflect on the evolving landscape of infectious diseases and public health. Yet rather than linger on setbacks, they look ahead, posing the critical question: “What are the future pandemic threats?”

To explore what transforms a simple pathogen into a global threat, they examine three key characteristics: transmission, virulence, and available countermeasures.

Transmission, it turns out, must strike a delicate balance. A virus must spread efficiently—fast enough to infect large populations, but not so aggressively that it incapacitates or kills its host before passing to the next person. Similarly, a pathogen that is too virulent may burn out quickly, unable to spread widely before its hosts succumb. As for countermeasures, their availability and effectiveness vary. Influenza, for instance, can be treated with antivirals, while diseases like Nipah virus remain without effective therapies.

At the time of this recording, H5N1 avian influenza stands out as a pressing concern. Dr. Vega reveals a startling fact: domestic cats may serve as an unexpected intermediary host, offering a new pathway for H5N1 to bridge the gap to humans. It’s a reminder of how creatively and unpredictably pathogens can bypass traditional barriers.

Dr. Sherbuk turns to Ebola as a striking example of how sheer virulence can catapult a disease to global attention. Past outbreaks in Africa overwhelmed health systems, exploiting cultural practices like burial rituals to fuel its spread. Even the limited number of U.S. cases during the 2014 outbreak stirred widespread public fear, driven by the virus’s high mortality rate abroad.

Not all dangerous pathogens are highly lethal. Some, like Zika virus, pose serious risks in specific populations—such as fetal abnormalities in pregnant women. Others, like HTLV-1, may cause chronic illnesses like leukemia and lymphoma.

While many pathogens naturally evolve to become less lethal—thereby enhancing their chances of transmission—some mutate unpredictably, becoming more dangerous. This is the ongoing concern with influenza: a seemingly mild strain could shift into something far deadlier.

The importance of countermeasures cannot be overstated. Yet in the aftermath of COVID-19, global readiness has been undermined by pandemic fatigue and the politicization of public health. Mistrust in vaccines, fractured health policy, and diminished international cooperation all threaten our capacity to respond to the next crisis.

But what if the next pandemic comes from a direction we didn’t anticipate?

Scientists have a name for this uncertainty: “Disease X.” The World Health Organization coined the term as a placeholder for the unknown. COVID-19 was once Disease X—until it had a name. The next one could emerge from zoonotic spillovers like HIV or Nipah, climate change, laboratory accidents, or even bioterrorism.

Whatever its origin, our best defense lies in robust surveillance, scientific agility, and global collaboration. Because the question isn’t if Disease X will come—but whether we’ll be ready when it does.

Dr Vega would like to thank her friend Job Meiller for his musical contribution to our segment breaks. Thank you Job!

Thanks also to Dr. Ana Velez, our artistic contributor, for her painting, "The Multivirus Pandemic Explosion," used in our episode thumbnail.

It felt inevitable. Years of declining childhood vaccination rates were bound to have consequences. In early 2025, those consequences became alarmingly real as a measles outbreak emerged in West Texas and Eastern New Mexico.

Before the introduction of the measles vaccine in 1963, the U.S. Centers for Disease Control and Prevention (CDC) estimated that measles infected three to four million Americans annually, causing 48,000 hospitalizations and 400 to 500 deaths each year. The introduction of the MMR (measles, mumps, and rubella) vaccine marked a turning point. The two-dose regimen—first administered between 12 and 15 months of age, with a second dose between 4 and 6 years—was remarkably effective. By 2000, measles was declared eliminated in the United States.

But in recent years, progress has unraveled. A dramatic drop in vaccination rates—fueled largely by the discredited claim linking the MMR vaccine to autism—has allowed this once-vanquished virus to resurge.

Today, vaccination rates in many states have dipped below the 95% threshold needed for herd immunity, and the current outbreak offers a grim reminder of what’s at stake. In Gaines County, Texas, where vaccine exemptions are especially high among the local Mennonite population, hundreds of measles cases have been reported—resulting in at least two deaths in Texas and New Mexico.

In this episode, hosts Dr. Vivian Vega and Dr. Jackie Sherbuk trace the recent history of measles in the U.S., focusing on the current outbreak in Texas and New Mexico. They tackle the question: Why is measles still so dangerous? The discussion includes common complications of the disease, current vaccination guidelines, and a thorough debunking of the alleged MMR-autism connection. They also highlight a growing concern: cases of vitamin A toxicity in children, stemming from widespread misconceptions about its role in measles treatment.

Dr Vega would like to thank her friend Job Meiller for his musical contribution to our segment breaks. Thank you Job!

Thanks also to Dr. Ana Velez, our artistic contributor, for her painting, "SSPE-Subacute Sclerosing Panencephalitis," used in our episode thumbnail.

Virology vanguard Dr. Bob Gallo is far from ready to slow down. Now in his seventh decade as one of America's top scientists, he could easily sit back and enjoy the fruits of his numerous and pioneering achievements. His groundbreaking work began in the 1970s with research into human retroviruses, including the discovery of the T-cell growth factor (IL-2) and the identification of the Human T-Cell Lymphotropic Virus (HTLV-1) in 1980, earning him his first Lasker Award, often referred to as “America’s Nobel Prize.” His subsequent research led to the identification of HIV-1 as the cause of AIDS, securing him a second Lasker Award. In the 1980s, he was the world’s most cited scientist. Along with his team, he developed the first HIV blood test, crucial for understanding the spread of AIDS and managing HIV patients. In the mid 1990's Gallo and his collaborators discovered chemokines, naturally occurring compounds that were essential for understanding how HIV infects cells. Dr. Gallo later founded the Institute of Human Virology at the University of Maryland School of Medicine in 1996 and co-founded the Global Virus Network (GVN) in 2011 to enhance global virus detection and management. Recently, Dr. Gallo and his team moved to Tampa, the new global headquarters for GVN, where he now serves as director of the University of South Florida (USF) Virology Institute and Head of the Microbial Oncogenesis Program at the Cancer Institute at Tampa General Hospital (TGH).

In the first part of this wide-ranging interview, Dr. Gallo shares insights into his entry into virology and his initial research into the etiology of certain cancers. This work included crucial discoveries around T cell growth factors, paving the way for identifying HTLV-1. He discusses his collaboration with CDC epidemiologists, which led to recognizing AIDS as being caused by a retrovirus. Once the HIV virus was identified as the cause, creating the first blood test for HIV had profound impacts on the epidemic and patient care.

In the second segment, Dr. Gallo discusses the origins of the HIV virus and its early global spread. He also reflects on the COVID-19 pandemic, why the focus on its origins is irrelevant and reflects on how to rebuild public trust in science and medicine, which may have been damaged during the pandemic.

In the concluding segment, Dr. Gallo talks about his reasons for joining USF Health and TGH and the research areas he finds most promising going forward. He speculates on the prospects for an HIV vaccine, the impact of artificial intelligence on virology, and why he doesn’t necessarily worry about the threat of the next global pandemic. Finally, Dr. Gallo opens up about how the early loss of his young sister deeply affected his life and his desired legacy.

Dr Vega would like to thank her friend Job Meiller, her YES Man, for the wonderful musical contributions and coming through on every idea she has. This time he contributes his renditions of Bruce Springsteen's "Streets of Philadelphia" and "Your Song," by Elton John. Thank you Job!

Thanks also to Dr. Ana Velez, our artistic contributor, for her painting, "HIV," used in our episode thumbnail.