Misinformation about vaccines may be leading to these delays.

One-third of children between the ages of 19-35 months don’t receive vaccines on time, leaving them vulnerable to preventable infectious diseases, and their complications, a new study finds.

The study revealed that 63% of children received vaccines on time before the age of three, as per Centers for Disease Control and Prevention guidelines, while 23% limited the number of shots per visit or skipped at least one vaccine. Another 14% were not compliant with guideline recommendations, according to data used from surveys at Emory University from 15,059 children nationwide showed.

The CDC recommends children be vaccinated against 14 illnesses in their first three years of life; Chickenpox (Varicella) Diphtheria, tetanus, and whooping cough (pertussis) (DTaP) (4th dose), Haemophilus influenzae type b disease (Hib) (4th dose), Measles, mumps, and rubella (MMR) (1st dose), Polio (IPV) (3rd dose), Pneumococcal disease (PCV13) (4th dose), Hepatitis A (HepA) (1st dose).

Vaccine delays were more common in children who moved across state lines, were not first-born, lived in the Northeast, were black or multi-race, and below the poverty level, according to the study.

“Some families work with their pediatrician to come up with a modified immunization schedule (vs. CDC schedule) or they will split up the combination vaccines, which ultimately ends up being more of a disservice to your newborn because of more overall injections given. Delaying vaccines, delays the body’s ability to develop an immune response, relying on immunity from rest of community” Dr. Shaliz Pourkaviani, who is a bicoastal neonatologist, said.

Vaccination has been named an effective public health intervention yet, parents are still choosing to delay or forgo vaccination for their children. Uncertainty about safety and necessity of vaccines, along with general mistrust of the pharmaceutical industry, has led to this recent trend, the study said.

“There is a general trend in vigilant families to delay or refuse vaccinations due to concerns about preservatives used in vaccines,” Pourkaviani said.

The study also confirms that misinformation about vaccines in recent years and reservations about giving too many vaccines at one time may be leading to these delays.

Authors of the study highlight a need for interventions to minimize vaccine delays that put children’s health, and public health, at risk.

“It is important to speak with moms and try to dissect each individual family’s concerns regarding vaccines. Often time’s parents don’t have a good understanding of why they are refusing, and seem to want to be a part of the anti-vaccine movement promoted by social media influencers/blogs and concepts that are not backed by reliable data” Pourkaviani said.

“As a nation we need to push for pharmaceutical industry to be more transparent regarding ingredients used,” Pourkaviani added.

Interventions should target both providers and parents, the authors of the study said.

For more information on vaccination schedules, safety and side effects, refer to the CDC’s website.

[Yalda Safai, MD MPH is a psychiatry resident in New York City and contributor to the ABC’s news Medical unit]