Podcast Summary: Today, Explained — "Why everyone is sick right now"

Date: January 11, 2026
Host: Jaclyn Hill (Vox)
Guests: Caitlin Jatalina (Epidemiologist), Carl Zimmer (Science Writer), Ellen Foxman (Yale School of Medicine)

Overview

This episode of Today, Explained dives deep into the current explosive cold and flu season of winter 2026. With widespread illness—from flu, COVID, RSV, to norovirus—host Jaclyn Hill and guests explore why this season is particularly bad, how viruses are evolving, why vaccines alone may not stop infection, and the real science behind "immune boosting." The episode also highlights how our immune systems actually work, what research says about virus transmission and protection, and what role (if any) AI might play in ending annual viral misery.

Key Discussion Points & Insights

1. Why is Everyone Sick Right Now?

• Record-High Flu Activity:

  • "Flu cases in the US are now at their highest levels on record... roughly 11 million cases reported. 5,000 deaths. In fact, 45 states tonight now reporting very high or high flu activity." (Jaclyn Hill, 02:02)
  • The problem isn’t limited to in-person transmission; even remote teams report simultaneous infections.
  • Multiple viruses are surging: flu (mainly H3N2), COVID, RSV, norovirus, and common cold.

• Virus Seasonality Factors:

  • "Cold weather really causes viruses to spread very quickly, as well as some social events... and these viruses just keep mutating." (Caitlin Jatalina, 02:50)
  • Social interactions and colder indoor environments boost transmission.

Timestamps

• Personal stories of illness: 01:07–01:57
• Current statistics and concern: 01:57–02:11
• Why this season is bad: 02:37–03:30

2. Flu Evolution and Vaccine Mismatch

• What's Circulating?

  • H3N2 Influenza A, specifically a "subclade K" strain, mutated over the summer in the Southern Hemisphere and is now dominant in the US.
  • "It's just simply bad luck that H3N2 evolved so much in the months before our season really took off." (Caitlin Jatalina, 04:27)

• Mutations Explained:

  • Drift (small, gradual changes): typical most years, means vaccines may not perfectly match—"our current vaccines will likely recognize some, but not all, of this updated virus." (Caitlin Jatalina, 04:27)
  • Shift (rare, major changes): can cause pandemics, not the case this year.

• What This Means:

  • More cases and more severe illness, even for those vaccinated.
  • Vaccines still matter: "It's [the flu shot] designed to prevent against hospitalization and you dying... it did some of its work." (Caitlin Jatalina, 05:54)
  • Not too late to vaccinate—immunity takes two weeks, and season hasn't peaked yet. Multiple flu strains circulate, so even after one case, another is possible.

Timestamps

• Mutation concerns: 03:30–04:27
• Vaccine efficacy and timing: 05:32–07:30

3. It's Not Just the Flu

• Other Viruses on the Rise:
  • COVID: "Covid right now is also starting to increase. Not as high as flu... but it is getting there." (Caitlin Jatalina, 07:36)
  • RSV: Particularly affecting infants.
  • Norovirus: Spreads through touch/contaminated surfaces, not just respiratory droplets.
  • "There's plumes of viruses everywhere you're going right now." (Caitlin Jatalina, 08:31)

Timestamps

• Viruses in circulation: 07:36–08:31

4. Immune "Hacks": What Works and What Doesn't

• Debunking Myths:

  • Supplements, cold plunges, “hacks” like hydrogen peroxide, deep breathing: "Dietary supplements actually do not work in preventing or reducing severity of illness." (Caitlin Jatalina, 09:14)
  • "There’s really inconclusive evidence and a lot of conflicting studies [for cold plunges, nasal breathing, saunas]."

• What Actually Helps?

  • Sleep: "Sleep is critical. This is when the immune system executes most of its repair process." (Caitlin Jatalina, 09:14)
  • Nutrition: Balanced, nutrient-dense diet.
  • Hydration: Helps transport immune cells and clear pathogens.
  • "Proper fluid balance really ensures your body can transport nutrients and immune cells and remove a lot of these pathogens and waste products." (Caitlin Jatalina, 09:14)

Timestamps

• Immune “hacks” and debunking: 08:31–10:28

5. Why Do Viruses Make Us Feel So Awful?

• The Body's Response:

  • Symptoms aren't just the virus—they’re your body’s defenses at work.
  • "A lot of what we feel when we are infected with a virus is just our body doing its level best to win the fight." (Carl Zimmer, 13:50)
  • Fever helps immune cells; inflammation is a defensive overdrive, but can cause harm when extreme.

• Why Viruses Mutate So Rapidly:

  • They employ “sloppy” replication, generating huge numbers of mutated offspring.
  • "One of them turns out to be really good and just better than the others. And it is just spreading like wildfire." (Carl Zimmer, 15:27)

Timestamps

• What is a virus/why symptoms happen: 11:24–13:50
• Mutation and viral dominance: 13:50–15:27

6. Why No Cure for Common Cold or Flu?

• Sheer Diversity & Evolution:

  • "If you can even find a recipe for a vaccine for one particular kind of cold virus... there are so many others." (Carl Zimmer, 16:06)
  • Viruses are ancient and outpace our science through their adaptability.

• AI: Not a Magic Bullet

  • While AI speeds up research (e.g., identifying viral strains via the Human Virome Program), “anybody who would tell you that... AI that has just been rolling out... is going to magically, instantly give us a vaccine for the cold is not being honest with you." (Carl Zimmer, 17:42)
  • Evolution and biology still present massive hurdles.

Timestamps

• Cure for common cold: 15:33–17:18
• Role of AI in virology: 17:18–19:34

7. How Our Immune System Actually Copes

• Adaptive vs. Innate Immune Response:

  • Adaptive: “What vaccines do is... show your immune system the size and shape of that virus, so it recognizes it and blocks it the next time.” (Ellen Foxman, 21:02)
  • Innate: Built-in, general defense—babies are born with it; kicks in fast on first exposure.

• Pandemic Impact:

  • Fewer viruses circulated during lockdown due to public health measures, leading to "immunity gaps," especially in young children for RSV.

• Not Everyone Gets Sick:

  • Only about half of people exposed to common cold viruses actually develop symptoms.
  • "What goes right when you get one of these viruses in your body, but you don’t get sick?" (Ellen Foxman, 20:50)

• When Getting Sick Has a Silver Lining:

  • Mild infections may “rev up” innate immune defenses and even help protect against other viruses temporarily.
  • "When you have a rhinovirus... if the flu's there, it will react against the flu as well." (Ellen Foxman, 24:43)

Timestamps

• Immunity basics: 20:05–21:49
• Impact of pandemic on immunity: 21:49–23:04
• Cross-protection of colds vs. other viruses: 23:30–25:51

Notable Quotes & Memorable Moments

• On Vaccination Efficacy:
  • “Even though you got the flu shot, it's not designed to protect against infection. It's designed to prevent against hospitalization and you dying.”
    —Caitlin Jatalina (05:54)
• On AI and Science Hype:
  • “Anybody who would tell you that... AI is going to magically, instantly give us a vaccine for the cold is not being honest with you. They’re not being honest about how AI works, and they're not being honest about how much there is to figure out about viruses and vaccines.”
    —Carl Zimmer (17:42)
• On Everyday Immunity:
  • "Only about half of the time do people who get those cold viruses even get sick... what goes right when you get one of these viruses in your body, but you don't get sick?"
    —Ellen Foxman (20:50)
• On Why Symptoms Hurt So Much:
  • “A lot of what we feel when we are infected with a virus is just our body doing its level best to win the fight.”
    —Carl Zimmer (13:50)

Practical Takeaways

• It’s not too late to get vaccinated; multiple flu strains mean repeat infections are possible in a single season.
• Quick “immune hacks” (supplements, cold plunges, etc.) don’t have strong scientific backing; focus on sleep, nutrition, and hydration.
• Viruses win by mutating rapidly; this is why science lags behind with vaccines or cures.
• Not every exposure leads to illness—understanding and supporting the immune system is key.

Recommended Actions

• Get your flu shot—even mid-season
• Prioritize sleep, nutrition, and hydration
• Don’t rely on viral social media immunity “hacks”
• Stay aware that evolution and viral diversity mean ongoing challenges for vaccines and treatments

Timestamps for Key Segments

• Why everyone is sick (Seasonal/viral factors): 01:57–03:30
• Virus mutations and vaccine mismatch: 03:30–05:32
• Effectiveness of flu shots: 05:32–06:45
• Multiple viruses at once: 07:30–08:31
• Immune boosting advice: 08:31–10:28
• How viruses work & why we feel sick: 11:24–13:50
• Why viruses mutate so fast: 13:50–15:27
• The limits of vaccines/AI: 16:06–19:34
• How immune systems fight back: 20:05–23:30
• Colds as immune system "training": 23:30–25:51

Summary by an expert podcast summarizer—preserving the original tone, citing speakers and timestamps for clarity.