Declining Childhood Vaccinations Could Increase Frequency of Infectious Disease Previously Eliminated

Declining childhood vaccination rates could potentially increase the frequency and size of outbreaks that were previously eliminated by vaccinations, according to results from a modeling study published in JAMA. The findings support the need for improved vaccination coverage to prevent the resurgence of previously eliminated infectious diseases in the United States.¹

The findings support the need for improved vaccination coverage to prevent the resurgence of previously eliminated infectious diseases in the United States. | Image Credit: Oksana Kuzmina - stock.adobe.com

According to the CDC, measles and rubella have been considered eliminated as vaccine-preventable infections, and it continues to target public health issues such as bacterial meningitis, human papillomavirus, cholera, hepatitis B, rabies, and tetanus. To date, smallpox is the only human disease that has been completely eradicated, with the CDC working with other global organizations to eliminate polio.²

In a study from HealthDay Harris Poll, at least half of US adults report that recent outbreaks and media coverage influenced their views on vaccines. Currently, there is an outbreak of measles in the US as well as an increase in pertussis and tuberculosis cases. According to the results, 67% of respondents said the local vaccine-preventable diseases impacted their decisions for immunization.³

In the modeling study, investigators aimed to understand the long-term effects of declining childhood vaccinations for measles, rubella, diphtheria, and poliomyelitis. The model estimated the risk of reemergence of the eliminated infectious diseases as well as complications associated with the diseases. At the start of the simulation, investigators used moderate state-level variation in childhood vaccine coverage from 2004 to 2023, which ranged from 88% to 96% for the measles, mumps, and rubella vaccine; 78% to 91% for diphtheria (covering the diphtheria, tetanus, and pertussis vaccine series); and 90% to 97% for the poliovirus vaccination series.¹

Investigators evaluated the validity, which demonstrated that it predicted cases that were aligned with recent historical estimates. Over a 25-year period with current state-level vaccination rates, the model predicted there would be 851,300 cases of measles, 190 cases of rubella, 18 cases of poliomyelitis, and 8 cases of diphtheria. Of those with measles, there would be 851 cases with postmeasles neurological sequelae, according to the investigators. Additionally, there would be 170,200 hospitalizations and 2550 deaths related to infections. In a scenario with MMR vaccination rates being 5% higher over 25 years, there would only be approximately 5800 cases of measles and 2700 cases when vaccination was 10% higher. When vaccination was 10% lower, the model estimated approximately 11.1 million cases of measles.¹

If routine childhood vaccination declined by 25%, investigators found that there would be approximately 26.9 million cases of measles within 25 years, 790 cases of rubella, 87,600 cases of poliomyelitis, and 11 cases of diphtheria. The model estimated 26,900 cases of postmeasles neurological sequelae, 100 cases of paralytic poliomyelitis, 1 case of congenital rubella syndrome, 5.4 million hospitalizations related to infections, and 80,600 deaths related to infections.¹

Under the current childhood vaccination levels, measles was predicted to return to endemicity in 83% of simulations at an estimated 20.9 years, according to the study authors, but other diseases likely would not return to endemicity. Additionally, if the state-level vaccination coverage was 5% higher, measles did not return to endemic levels. Under 25%, poliovirus became endemic in 11% of simulations with a mean time of 23.3 years, but diphtheria and rubella did not become endemic. At under 50%, measles returned to endemicity in 99.8% at a mean of 4.9 years, rubella returned in 100% of simulations at 18.1 years, poliovirus returned in 55.6% at a mean time of 19.6 years, and diphtheria returned in less than 1% of simulations but took more than 20 years, according to the study authors.¹

REFERENCES

1. Kiang MV, Bubar KM, Maldonado Y, Hotez PJ, Lo NC. Modeling Reemergence of Vaccine-Eliminated Infectious Diseases Under Declining Vaccination in the US. JAMA. Published online April 24, 2025. doi:10.1001/jama.2025.6495

2. CDC. Vaccine-Preventable Diseases. July 30, 2024. Accessed April 24, 2025. https://www.cdc.gov/global-immunization/diseases/index.html

3. Nowosielski B. Media Coverage, Local Outbreaks Changing Views on Vaccine Hesitancy. Drug Topics. April 2, 2025. Accessed April 24, 2025. https://www.drugtopics.com/view/media-coverage-local-outbreaks-changing-views-on-vaccine-hesitancy