Vaccines given to infants and young children have saved 732,000 lives, prevented 322 million illness and 21 million hospitalizations in the past 20 years, according to a new report from the Centers for Disease Control and Prevention.

During the study period, nearly 709 million children were born in the United States and each was saved from four infectious diseases, on average, thanks to vaccinations, according to CDC officials. The report was released at a time when many parents are uncertain about the benefits of vaccines, "leading some to skip or delay routine childhood shots," USA Today reported.

Authors of the report based their estimates on the CDC's annual immunization surveys and published reports showing the known efficacy of vaccines, as well as complication rates from infectious diseases.

"We have roomfuls of evidence" showing that vaccines are some of the safest medications available, William Schaffner, an infectious disease specialist and professor at the Vanderbilt University School of Medicine in Nashville, told USA Today . "But rumors and conspiracy theories still spread. Young parents today haven't seen these disease, and they don't respect and fear them."

For example, before the measles vaccine became available in 1963, the contagious illness infected nearly 500,000 people a year, causing 500 deaths and 48,000 hospitalizations, USA Today reported. According to the CDC, 129 people in the United States have developed measles so far this year in 13 outbreaks.  Most of the people who acquired measles in 2014 were not vaccinated or did not know their vaccination status.

"Current outbreaks of measles in the [United States] serve as a reminder that these diseases not only a plane ride away. Borders can't stop measles, but vaccinations can," CDC Director Dr. Tom Frieden told reporters, according to LiveScience.

The federal agency recommends people of all ages to keep up to date with their vaccinations.