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Receiving at least one dose of the measles, mumps, and rubella (MMR) vaccine was associated with lower risk of early childhood inflammatory bowel disease (IBD), a retrospective cohort study found.

Among over 1.3 million privately insured children, receiving at least one MMR vaccine dose was associated with a 21% lower risk of developing IBD compared with not getting vaccinated (HR 0.79, 95% CI 0.64-0.96, P=0.018), after adjusting for a number of factors including sex and vaccine allergy, reported Catherine Kim, MD, MPH, of the University of Michigan in Ann Arbor, and colleagues.

This relationship remained even after further adjusting for preterm birth and childhood comorbidities (HR 0.80, 95% CI 0.66-0.98, P=0.031), and having older siblings with IBD (HR 0.79, 95% CI 0.64-0.96, P=0.018), the authors noted in .

When looking at the effect of the MMR vaccine on Crohn's disease or ulcerative colitis individually, similar relationships were seen, but they did not reach significance.

"Parents hesitant to vaccinate their children due to poor health status should be reassured that the risk of chronic conditions is minimal with this vaccine, and parents hesitant to vaccinate due to another child affected with autoimmune disease should also be reassured that the vaccine does not seem to be associated with increased risk," Kim and team wrote.

Reached for comment, Russell Cohen, MD, of the University of Chicago Medicine told 麻豆传媒 that "the theory that the authors purport is that since infections such as the measles (in particular) may result in a change in the body's response to infections, that may impact the microbiome."

"Whether this would impact the rates of IBD (i.e., higher, lower, or not at all) is debatable, as various studies have shown different results," noted Cohen, who was not involved in the study. "This study should be reassuring for parents (and parents to be), as these vitally important vaccines were not shown to be implicated in the development of Crohn's or ulcerative colitis, and should be given without hesitation per current vaccination guidelines."

Reached for comment, Sandra El-Hachem, MD, of the Allegheny Center for Digestive Health in Pittsburgh said: "This is a very interesting study showing possibly a protective effect of MMR vaccine as it pertains to development of childhood IBD."

"Childhood IBD can be quite a severe disease process and having a simple, safe, and accessible way to potentially decrease the risk of developing future childhood IBD is encouraging," El-Hachem told 麻豆传媒.

IBD affects about 1.3 million people in the U.S., with a growing global incidence among children, especially those younger than 7 years, Kim's group noted. "The explanation for these increases is not entirely clear, although it is likely due to a range of environmental factors including earlier detection; changes in the microbiome resulting from changes in antibiotic prescription patterns and utilization of appendectomy; and viral gastrointestinal infections."

For this study, Kim and colleagues examined de-identified claims data from Optum Clinformatics Data Mart on 1,365,355 children who were born between 2001 and 2018. Most received at least one MMR vaccine dose (n=1,224,125) starting at 12 months in accordance with CDC recommendations.

Participants had to have continuous medical and pharmacy healthcare coverage from birth until at least age 2. Siblings who were older than index children by 6 months to 17 years and continuously enrolled in health insurance during the study were also included. Nearly all attended a wellness visit before age 2.

The main analysis adjusted for sex, year of birth, geographic region, vaccine allergy, and history of seizures.

Overall, 377 kids developed IBD, 216 with Crohn's disease and 161 with ulcerative colitis.

Children who received both MMR doses were older during the study compared with those who did not receive any doses (median age 6 vs 3 years) and were initially diagnosed with IBD at older ages (8 vs 4.5 years). Those unvaccinated against MMR were less likely to have vaccine allergies (0.5% vs 0.7%) and seizures (3% vs 4%), and to be born preterm (5% vs 7%) versus those vaccinated with at least one dose. They also had a lower modified childhood chronic conditions score (0.39 vs 0.48).

In sensitivity analyses that restricted the sample of children to those who were enrolled for at least 5 years, vaccination with MMR was still associated with lower risk of IBD after adjusting for the covariates in the initial analysis (HR 0.78, 95% CI 0.64-0.96), preterm birth and childhood comorbidities (HR 0.80, 95% CI 0.65-0.98), and having older siblings with IBD (HR 0.78, 95% CI 0.64-0.96). Vaccination was also still associated with lower risk after adjustment for antibiotics as a time-varying covariate (HR 0.77, 95% CI 0.63-0.95), although antibiotic use itself was not associated with risk of IBD (HR 1.24, 95% CI 0.76-2.02).

Kim and colleagues noted that their findings may be limited by confounding factors related to parents' hesitancy on vaccination. Since most children were younger, the results may not apply to older kids. Moreover, not all administrative claims data relied on diagnoses based on biopsies.

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