Missing Early Vaccines? Your Child Is 7 Times More Likely to Skip the MMR Shot

Babies who don't receive their first vaccines on schedule at 2 months old are more than seven times more likely to miss their measles, mumps, and rubella (MMR) shot by age 2, according to groundbreaking new research. This finding suggests that vaccine hesitancy begins much earlier than previously understood, creating a domino effect that puts children at risk for serious diseases.

The study, published in JAMA Network Open, analyzed electronic health records from over 321,000 children born between 2017 and 2023 who had regular access to healthcare. Researchers found that vaccination patterns established in a baby's first few months strongly predict whether they'll receive critical immunizations later in childhood.

What Makes the 2-Month Visit So Critical?

At 2 months old, babies are scheduled to receive their first round of vaccines protecting against multiple serious diseases. The Centers for Disease Control and Prevention (CDC) recommends immunizations against hepatitis B, rotavirus, diphtheria, tetanus, pertussis, polio, Haemophilus influenzae type b, and pneumococcal disease during this visit.

"There's evidence from this study that very early vaccination delays lead to later vaccination delays and even missed vaccination for measles," said Nina Masters, an epidemiologist and lead author of the study. "This shows that hesitancy is really starting early and has a long arc."

The research revealed that children who were late receiving their early vaccines faced significantly higher odds of missing the MMR vaccine entirely:

• 2-Month Delays: Children late on 2-month vaccines were 6.96 times more likely to miss MMR vaccination
• 4-Month Delays: Those late on 4-month vaccines faced 6.16 times higher odds of missing MMR
• Consistent Pattern: The strongest predictor of future vaccination was having received any vaccine in the past

Why Are MMR Vaccination Rates Declining?

The timing of this research is particularly concerning given recent measles outbreaks across the United States. In 2025, the country reported 2,065 confirmed measles cases—the highest number in over three decades. The U.S. is now at risk of losing its measles elimination status, which has been maintained since 2000.

The study found troubling trends in MMR vaccination rates. On-time first-dose MMR vaccination declined from 79.9% in 2021 to 76.9% in 2024—a three percentage point drop in just three years. More concerning, the percentage of children who hadn't received any MMR vaccine by age 2 rose from 5.3% in 2020 to 7.7% in 2024.

"It wasn't that more people were delaying. It was that more people were not getting the MMR vaccine for their babies at all by 2 years," Masters explained.

What Can Parents and Doctors Do?

The research highlights the critical importance of early pediatric visits and building trust between healthcare providers and families. Currently, just under half of babies in the study followed the American Academy of Pediatrics' recommended visit schedule, which includes appointments within the first week, at 1 month, 2 months, 4 months, 6 months, and 9 months.

"The most promising avenue for intervention is a doctor's recommendation," said Noel Brewer, a professor of health behavior at the University of North Carolina. Studies consistently show that trusted medical practitioners have the greatest influence on parents' vaccination decisions.

However, pediatricians face a narrow window to establish trust and educate parents about vaccine importance. "So it does create this window of opportunity that's quite short and puts the onus, I think, on those pediatricians really to talk about vaccines early, build trust early, build education and familiarity right off the bat," Masters noted.

The study's findings are likely conservative since it only included children with consistent healthcare access and insurance coverage. "These numbers are conservative in terms of the magnitude of these effects if we were to include broad populations," Masters said.

With measles being one of the most contagious infectious diseases, even small declines in vaccination coverage can lead to explosive outbreaks. The current research underscores the urgent need for healthcare providers to address vaccine hesitancy early and often, starting from a baby's very first medical visits.