DESCRIPTION

• A decision by a patient or parent to delay or refuse a vaccine recommended by a health care provider
• Considered one of the top 10 public health threats by the World Health Organization
• Comprises a range of behaviors from unquestioning acceptance of vaccines to cautious or selective acceptance to refusal of all vaccines
• Influenced by the interaction of several factors related to confidence, complacency, and convenience
  • Confidence: lack of trust in vaccines, health care providers, and/or health care system
  • Complacency: low prioritization of vaccination related to low perceived risk of vaccine preventable diseases
  • Convenience: barriers to accessing immunization services (e.g., vaccine cost or difficulty getting to immunization provider)

EPIDEMIOLOGY

• Majority of adults in the United States believe that vaccination is extremely or very important, but increasing proportion believes that vaccines are more dangerous than diseases they prevent.
• 20% of families seen by pediatricians request to delay at least one vaccine.
• More than one third of pediatricians will accept requests to delay certain vaccines, but <10% agree with such requests.
• In 2020, ~70% of a 2015 to 2018 birth cohort completed the combined seven vaccine series, and 1% received no vaccines by 24 months.
• Rate of infants who receive first vaccine dose at the age of 4 to 5 months increased from ~50/10,000 to 100/10,000 across five successive birth cohorts (2004 to 2008).
• In the 2020 to 2021 school year, exemption rates for kindergarten school entry requirements ranged from 0.1% to 8.2% across U.S. states.

RISK FACTORS

Because of the heterogeneity of vaccine hesitancy, there is no one singular set of risk factors. However, contributors to refusal include the following:

• Less experience with vaccine-preventable diseases due to decreased disease incidence leading to underappreciation of disease risk and severity; parents may question the need for vaccines.
• Vaccine safety concerns—as concerns about risk of vaccine-preventable diseases decreases, parents may worry more about potential risks of vaccination.
• Rapid dissemination of information increases the likelihood of access to misinformation about vaccines that may reinforce vaccine safety concerns.
• Antivaccine advocacy by prominent public persona amplifies antivaccine beliefs.
• Increase in scientific denialism, which is rejection of facts for which there is well-established scientific consensus
• Rapid development and emergency authorization of new vaccines during the COVID-19 pandemic
• Politicization of vaccination and vaccine mandates
• Distrust of public health authorities, amplified during pandemic period

GENERAL PREVENTION

• Early communication about vaccines with parents can help identify and address concerns to prevent vaccine refusal or delay.
• Opportunities may include prenatal visits, in the nursery prior to discharge from the hospital, and at or after the newborn visit.

COMMONLY ASSOCIATED CONDITIONS

• For some parents, vaccine refusal may be associated with refusal of other health care interventions.
• Some parents may accept all recommended vaccines but request an alternative schedule. Alternative vaccine schedules spread out the recommended vaccine doses, resulting in immunization delay for some vaccines.
• Reasons for alternative vaccine schedules:
  • Belief that receiving multiple injections at the same time may overwhelm the immune system
  • Belief that the recommended schedule exposes infants to too much aluminum