Editor's note: Video sound bites of Dr. Jennifer Squires speaking to this topic are available for media. Download 720p version here . Download the SD version here . Download accompanying b-roll here .

According to the World Health Organization , 1 in 5 children is still missing out on routine lifesaving immunizations. These immunizations could help prevent diseases that result in 1.5 million deaths each year.

In 2013 alone, 21.8 million infants around the world did not receive lifesaving vaccines. Lack of access, inadequate supply and a shortage of information about immunizations all contribute to these numbers.

The Centers for Disease Control and Prevention describe vaccines as containing “the same germs that cause the disease, but the germs have been either killed or weakened to the point that they don’t make you sick.” Vaccines help the immune system build up resistance to dangerous diseases.

‘Herd immunity’

“Vaccines are 90 to 100 percent effective,” said Dr. Jennifer Squires, a pediatrician at Novant Health Elizabeth Pediatrics. “They’re so important because they help prevent diseases that truly could be life-threatening for our children.

However, some children are not able to get vaccines for certain medical reasons, or because they are too young to be vaccinated. This leaves children without protection, therefore having to rely on “herd immunity.”

“Herd immunity is a newer concept among parents who believe their child could be protected from disease by being around other people who have been vaccinated,” Squires said.

This idea is not effective way to prevent the spread of disease, according to the doctor. “You’re relying on other people to immunize their children,” Squires said. “If several people in the herd don’t get immunized, then you are exposing them to those illnesses that they haven’t been vaccinated against.”

No link to autism

There has been a fear of vaccines causing autism, thanks to misinformation from the 1980s where a doctor in England said there was a supposed link. “It’s been completely disproven,” Squires said. “The link between autism and vaccination is based on false science and that doctor’s study has been proven wrong by multiple other studies,” she said.

Vaccines given to children can help prevent diseases such as diphtheria, tetanus, chickenpox, polio and measles, but also pneumonia and rotavirus diarrhea – two of the biggest killers in children younger than 5. For adolescents and adults, vaccines are available to prevent influenza and meningitis, as well as cervical and liver cancer.

Because of immunizations, today there are fewer cases of mumps, rubella and other illnesses, but Squires points out that these diseases have not entirely been eradicated. Last year the United States saw a multistate outbreak of measles, a disease that can cause brain damage and even death. The outbreak serves as a reminder that a decision not to vaccinate may affect many others: While some people who caught measles were unvaccinated by choice, others were infants too young to get immunized.