Why Vaccines Work

As more and more parents are choosing not to vaccinate their children or are vaccinating them later, diseases like measles are making a comeback. Are vaccines safe? How do vaccines work? Why do some people claim there is a link between vaccines and autism? This week we look at why are people afraid of something that has saved so many lives, and look at the history and science of vaccines.

Season 3 Episode 17 Length 06:38 Premiere: 02/16/15

Recent Episodes

How HIV Started a Century Before Anyone Noticed

S14 E8 Length 27:32 Premiere Date 07/16/26

The New Kind of Heat Humans Can’t Handle

S14 E7 Length 21:23 Premiere Date 07/01/26

Scientists Finally Figured Out What Love Is For

S14 E6 Length 16:47 Premiere Date 06/11/26

We've never seen an atom. But we know what they look like.

S14 E5 Length 16:47 Premiere Date 05/28/26

Infinity isn’t a number. It's something much weirder.

S14 E4 Length 10:51 Premiere Date 05/14/26

Something Strange Happens When You Flatten the Earth…

S14 E3 Length 24:25 Premiere Date 04/21/26

Specials

The Mystery of Earth's Disappearing Giants

Length 21:29 Premiere Date 09/16/21

Dung Beetles: The Poop-Rolling Stargazers of the Serenget

Length 17:08 Premiere Date 09/01/21

These Butt-Tickling Ants Are Endangered Butterfly Bodyguards

Length 20:59 Premiere Date 08/18/21

These Death-Eating Scavengers Are Real Life-Savers

Length 29:33 Premiere Date 08/04/21

Elephant Moms Carry the Wisdom of Generations

Length 25:36 Premiere Date 07/21/21

Are Some Species More Important Than Others?

Length 25:47 Premiere Date 07/08/21

The Surprising Species That Everything Else Depends On

Length 25:47 Premiere Date 07/08/21

The Superb Owl!

Length 04:11 Premiere Date 02/02/17

The 12 Days of Evolution - Complete Series!

Length 17:43 Premiere Date 01/26/17

The Surprising Origin of Thanksgiving Foods

Length 05:09 Premiere Date 11/13/16

Do Animals Mourn Their Dead?

Length 04:17 Premiere Date 10/23/16

Season 3 Episodes

Show Episodes

Show Clips & Previews

The Strange Science of the Placebo Effect

S3 E55 Length 06:15 Premiere Date 11/16/15

The REAL Physics of Hot Air Balloons!

S3 E54 Length 05:51 Premiere Date 11/10/15

This is a SUPER BLOOD MOON! Lunar Eclipses Explained

S3 E53 Length 03:58 Premiere Date 11/02/15

Do Other Animals Mourn Their Dead?

S3 E52 Length 04:59 Premiere Date 10/26/15

How To Hit A Fastball (According To Science!!!)

S3 E51 Length 05:55 Premiere Date 10/19/15

What Color Is The Moon?

S3 E50 Length 03:39 Premiere Date 10/12/15

El Niño and Why We Can't Predict the Weather

S3 E49 Length 06:16 Premiere Date 10/05/15

Why Do We Have to Sleep

S3 E48 Length 07:54 Premiere Date 09/28/15

Theory vs Hypothesis vs Law

S3 E47 Length 06:48 Premiere Date 09/21/15

Eight Incredible Deep Sea Oddities

S3 E45 Length 02:34 Premiere Date 09/01/15

I Don't Think You're Ready for These Jellies

S3 E44 Length 04:46 Premiere Date 08/31/15

My Date With A Giant Pacific Octopus!

S3 E43 Length 03:07 Premiere Date 08/30/15

Cuttlefish: Tentacles In Disguise

S3 E42 Length 03:54 Premiere Date 08/29/15

The Ruin and Rise of Monterey Bay

S3 E41 Length 03:38 Premiere Date 08/28/15

What Has New Horizons Taught Us About Pluto?

S3 E40 Length 05:55 Premiere Date 08/11/15

What Is Fire?

S3 E39 Length 03:39 Premiere Date 07/27/15

Why Do We Laugh?

S3 E38 Length 06:03 Premiere Date 07/27/15

Why Are Cicadas So Good At Math?

S3 E37 Length 05:32 Premiere Date 07/20/15

Your Salad Is Trying To Kill You

S3 E36 Length 06:03 Premiere Date 07/13/15

How Does A Canyon Become Grand?

S3 E35 Length 04:03 Premiere Date 07/06/15

How Thomas Jefferson Saved America With a Dead Moose

S3 E34 Length 06:00 Premiere Date 06/29/15

Why Are The Bees Dying?

S3 E33 Length 04:01 Premiere Date 06/22/15

Which Came First - Flowers or Bees?

S3 E32 Length 05:19 Premiere Date 06/15/15

The Surprising Places We Waste Energy

S3 E30 Length 03:26 Premiere Date 06/01/15

When Will We Stop Using Oil?

S3 E29 Length 05:10 Premiere Date 05/29/15

Does The Moon Really Orbit The Earth?

S3 E28 Length 02:44 Premiere Date 05/18/15

What's The Loudest Possible Sound?

S3 E27 Length 03:49 Premiere Date 05/11/15

Is Ultron Inevitable?

S3 E26 Length 07:42 Premiere Date 04/24/15

Antibiotic Resistance and the Rise of Superbugs

S3 E25 Length 07:20 Premiere Date 04/15/15

What Color is the Universe?

S3 E21 Length 02:51 Premiere Date 03/16/15

Your #ScienceWoman Heroes

S3 E20 Length 04:46 Premiere Date 03/05/15

Zombie Parasites!

S3 E19 Length 06:01 Premiere Date 03/02/15

Why Does February only have 28 days?

S3 E18 Length 04:28 Premiere Date 02/23/15