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Declining Vaccination Rates and Increasing Disease Outbreaks are a Troubling Trend

Childhood vaccination rates have been declining in recent years and preventable diseases like measles and whooping cough are on the rise. The Centers for Disease Control and Prevention (CDC) sheds light on these trends, attempts to explain them, and is working to reverse them.

Lower Vaccine Rates and Increasing Exemptions for Kindergartners

According to the CDC, the 2023-2024 school year vaccination rates for kindergartners in the United States decreased for all reported vaccines from the previous year, while the percent of children with vaccine exemptions increased to a record high. This downward trend has many health experts concerned about the potential for a variety of disease outbreaks due to declining vaccinations.

The vaccine rate for kindergartners during the 2023-2024 school stands at 92.3% for diphtheria, tetanus, and acellular pertussis vaccine (DTaP), and 92.7% for the measles-mumps-rubella (MMR) vaccine. The vaccine rate for MMR is down from 93.1% the prior year, and down from 95% pre-pandemic, in 2019. The U.S. Department of Health and Human Services set a goal that at least 95% of kindergartners will have received two doses of the MMR vaccine — a threshold require to prevent outbreaks of these highly contagious diseases.

During the 2023-2024 school year, vaccine exemptions increased in 40 states and D.C., with 14 states reporting exemptions exceeding 5%, significantly above the national average of 3.3%. The increase in exemptions was primarily due to non-medical exemptions, such as religious or philosophical reasons.

The Impact of Declining Vaccination Rates

This year, the U.S. has seen a variety of disease outbreaks tied to declining vaccination rates. Currently, the CDC estimates that more than 250,000 kindergartners are potentially not protected against measles. In 2024, the CDC has reported 15 measles outbreaks (defined as three or more related cases), compared to four in 2023. Of the total 271 cases of measles this year, 89% of all age groups affected were unvaccinated or their vaccination status was unknown, and 41% of cases involved children under five years of age.

Whooping cough cases are also on the rise this year. Extremely contagious, the CDC estimates that about 80% of people with no vaccination will get whooping cough if exposed to an infected person. As of August 2024, the CDC has logged more than 12,000 known cases of whooping cough — up from 3,081 cases during the same period in 2023. In 2019, more than 18,000 cases of whooping cough were reported in the U.S. This number declined to approximately 2,000 in 2021 when more precautions were taken due to COVID-19. As the cases tick back up to normal pre-pandemic levels, the risk increases due to falling vaccination rates.

Regarding the influenza vaccine, among children born in 2021 receiving more than 2 doses of influenza vaccine, the rate declined to 53.4%, down from 63.8% in 2019. This is concerning as pediatric flu deaths hit a new record in the 2023-2024 season — 200 flu-related deaths compared to the previous high of 199 during the 2019-2020 season.

During the 2022-2023 flu season, the CDC reported: Of the 106 deaths at the time of the report (Feb. 10, 2023),103 children were eligible for vaccination, and the vaccination status was known for 81 of those children; 90% of those children were not fully vaccinated against the flu. In past seasons, about 80% of children who died from flu have not been fully vaccinated.

What is Herd Immunity?

The World Health Organization explains the importance of keeping the vaccination rates high: The percentage of people who need to be immune in order to achieve herd immunity varies with each disease. For example, herd immunity against measles requires about 95% of a population to be vaccinated. The remaining 5% will be protected by the fact that measles will not spread among those who are vaccinated. For polio, the threshold is about 80%. The proportion of the population that must be vaccinated against COVID-19 to begin inducing herd immunity is not known. 

Why is the Childhood Vaccine Rate Decreasing?

The drop in childhood vaccine rates can be attributed to several factors, including a disruption in routine healthcare during the pandemic, limited access to care, misinformation spreading about vaccines, and distrust in public health.

Coverage among children born during 2020–2021 varied by race and ethnicity and was generally lower among those covered by Medicaid or other nonprivate insurance, uninsured children, children living below the federal poverty level, and children living in rural areas.

Data from the CDC’s National Immunization Survey-Child (NIS-Child) was analyzed to estimate coverage with childhood vaccines recommended by the Advisory Committee on Immunization Practices among U.S. children by age 24 months. Coverage with nearly all vaccines was lower among children born in 2020 and 2021 than it was among those born in 2018 and 2019, with declines ranging from 1.3 to 7.8 percentage points.

Several studies have documented a negative effect associated with the COVID-19 pandemic on routine pediatric vaccination that could have affected children born in 2020 and 2021. A recent analysis examining parental vaccine hesitancy during 2019–2022 revealed an increase in hesitancy among parents of children aged 5–11 years after authorization of the COVID-19 vaccine, whereas hesitancy remained stable among parents of children aged six months to four years.

Parental vaccine hesitancy might be contributing to the low levels of influenza vaccination coverage. Hesitancy regarding the influenza vaccine has shown a stronger correlation with COVID-19 vaccine hesitancy than with other childhood vaccines, suggesting that parents may view the influenza vaccine differently than routine non-COVID childhood vaccines.

What is Being Done to Reverse the Trend?

Public health officials aim to combat vaccine hesitancy by collaborating with communities to disseminate accurate information. The CDC recently launched an initiative called Let’s Rise (Routine Immunizations on Schedule for Everyone), which aims to get immunizations back on track by providing actionable strategies, resources, and data to support getting all Americans back on schedule with their routine immunizations to protect everyone from vaccine-preventable disease and disability.

The American Academy of Pediatrics (AAP) has advice for clinicians who are helping parents who are hesitant about having their children vaccinated. Vaccine hesitancy is commonly associated with concerns about vaccine safety. The AAP encourages clinicians to refresh their knowledge of vaccine safety and provides resources for guiding these conversations with parents and countering common misconceptions.

You can learn more at cdc.gov.