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RFK Jr. has raised doubts about vaccines, but data shows how many lives they've saved

Measles outbreak expands in West Texas
Measles outbreak expands in West Texas 05:10

In his inaugural speech, President Trump vowed to "keep our children healthy and disease free," but his new secretary of the Department of Health and Human Services, Robert F. Kennedy Jr., has a long history of raising doubts about vaccines — despite decades of evidence showing they've saved millions of people from debilitating illness or death. 

"People forget what it used to be (before vaccines)," CBS News chief medical correspondent Dr. Jon LaPook said on "CBS Mornings Plus," pointing to data showing a huge decline in cases and deaths from these diseases compared with pre-vaccine levels.

"If you look at the 10 top childhood illnesses every year, vaccines prevent more than 1 million cases and more than 10,000 deaths" in the U.S., he said. Worldwide, the numbers are even greater, with an estimated 2-3 million lives saved by childhood vaccinations each year. 

Here's what else to know about the impact of vaccines.

How do vaccines work?

Vaccines work by imitating organisms like viruses and bacteria without making you sick. "That gives your immune system a chance to build up defenses so you're better prepared to fight a future infection," LaPook said.

Your immune system creates specific defenses called antibodies against the imitation pathogen — known as an antigen — introduced by the vaccine. "An antigen might be a germ that has been killed or changed so it cannot cause disease. It can be something that looks or behaves like a pathogen, a harmless part of a pathogen, or instructions for the body to manufacture the harmless part," according to Johns Hopkins Medicine.

Then if you encounter the actual pathogen later in life, your immune system is prepared to respond quickly to fight it.

Some vaccines effectively block illness, while others help prevent you from getting more severely sick if infected. So while it is true you can still get some illnesses after you've been vaccinated — like the flu or COVID, for example — the vaccines are still helpful in reducing the risk of severe illness or death.

If your body has a strong immune reaction to a vaccine, you might feel tired or experience body aches, headache, swollen lymph nodes or even a fever, according to Johns Hopkins Medicine. These potential side effects are normal and typically last no more than a day or two.

What do vaccines accomplish?

Vaccines have vastly reduced deaths in early childhood and largely eradicated certain diseases that used to cause dreaded epidemics. 

A recent study led by the World Health Organization estimates that vaccines, including immunizations against polio, measles and 12 other once-common diseases, have saved an estimated 154 million lives worldwide over the past 50 years. Measles vaccines alone have averted the deaths of about 94 million people, the analysis found.

In recent years, however, with backsliding immunization rates, health officials are starting to see the effects of skipping shots.

"We don't have to remember too far back to see what happens because of vaccination rates, when there aren't requirements and people don't have access," Dr. Carolyn Bridges, the CDC's former associate director for adult immunizations, recently told CBS News, citing a polio case that emerged in New York in 2022

"That's just mind-boggling that we can have a polio resurgence, in a country with all of our resources. It doesn't take all that much for diseases still circulating in other places to retake hold."

Polio cases and deaths before and after vaccines

Outbreaks of polio once killed thousands of Americans and left many survivors paralyzed, until the disease was virtually eliminated in the U.S. by vaccines that first rolled out in the 1950s.

For decades now, the polio vaccine (inactivated polio vaccine or IPV) has been part of the routine childhood immunization schedule in the U.S., as it's the best way to protect against the virus. There is no cure. 

A total of four doses is recommended for the best level of protection. Research shows two doses of IPV provide about 90% protection while three doses provide at least 99% protection

Measles cases and deaths before and after vaccines

Despite being easily preventable with a readily available vaccine, measles cases have been on the rise in recent years, due largely to an uptick in people skipping vaccination. Measles is highly contagious, and lower vaccination rates give it an opening to spread.

Before the vaccine became available in the 1960s, measles was very common in childhood. About 48,000 Americans were hospitalized for it each year, and about 500, mostly children, would die.

One dose of the MMR vaccine, which covers measles, mumps and rubella, is 93% effective against measles and the recommended two doses is 97% effective, research shows. 

Most people who are vaccinated will be protected for life, major health organizations say.

Rubella cases and deaths before and after vaccines

Rubella, also known as German measles, is especially dangerous during pregnancy, when it can cause miscarriage, stillbirth or severe birth defects. 

During a major outbreak in the U.S. in the mid-1960s, before the vaccine, records show 11,000 pregnant women lost their babies, 2,100 newborns died, and about 20,000 babies were born with lifelong disabilities due to the virus.

The MMR vaccine, first introduced in 1971, is about 97% effective at preventing rubella after just one dose, research shows. 

Though rubella is no longer endemic — meaning constantly present — in the United States, it remains a problem in other parts of the world. This means it can be brought into the U.S. by people infected in other countries, making vaccination important to prevent illness and outbreaks. 

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