More than 75 Nobel laureates this week signed a letter asking the U.S. Senate not to confirm

Health and Human Services Secretary nominee Robert F. Kennedy Jr. citing his opposition to vaccines

among their concerns. As we delve deeper into a range of issues connected to the incoming

Trump administration, William Brangham is back with

another explainer. This time, a look at Kennedy's record on vaccines and what impacts he could

have leading the nation's health agencies. Shots of the new vaccine stimulate production by the

body of billions of protective antibodies which build a wall. Vaccines are easily one of modern medicine's most successful interventions.

Over the past two centuries, they virtually eradicated diseases,

like smallpox, polio, measles, and many others

that once regularly disfigured, disabled, and killed hundreds of millions of people around the world,

many of them children. Dr. Michael Osterholm directs the Center for Infectious Disease Research

and Policy at the University of Minnesota. But the bottom line is, for every two days we've lived

in the last century, we've gained a day of life expectancy.

That's incredible.

And it's because of these tools, notably vaccines, that that's happened.

That's not to say there are no risks to them, including occasional allergic reactions,

injuries, and in rare cases, deaths.

And public health experts like Osterholm say it is important to examine and continually monitor any adverse effects. But on balance, those risks are far lower than those of

the diseases they're protecting against. If today I were in an automobile accident and I had my

seatbelt time, but somehow the seatbelt jammed and I was

unfortunately trapped in the car and the car caught on fire, this would be a horrible tragedy.

Would anybody say we got to eliminate seatbelts now? No, because in fact there have been

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