What are the guidelines for spacing out vaccinations?

Guidelines for Spacing Out Vaccinations

Vaccination providers should adhere as closely as possible to the recommended childhood immunization schedule, as clinical studies have shown that recommended ages and intervals between doses provide optimal protection and have the best evidence of efficacy. 1

General Principles for Vaccine Spacing

• Recommended childhood vaccination schedules are revised annually and published each January by the Advisory Committee on Immunization Practices (ACIP) and the American Academy of Family Physicians (AAFP) 1
• Physicians and healthcare providers should ensure they are following the most up-to-date schedules, which are available from CDC's National Immunization Program website 1
• Vaccines requiring multiple doses (inactivated vaccines, toxoids, recombinant subunit and polysaccharide conjugate vaccines) need proper spacing for development of adequate and persisting antibody response 1

Minimum Intervals Between Doses

• Vaccine doses should not be administered at intervals less than the minimum intervals or earlier than the minimum age 1
• The ACIP provides specific guidance on minimum intervals between doses for catch-up vaccinations when a person is behind schedule 1
• A vaccine series does not need to be restarted, regardless of the time that has elapsed between doses 1

Exceptions and Special Considerations

• Doses administered less than 4 days before the minimum interval or age can be counted as valid 1
• Doses administered 5 or more days earlier than the minimum interval or age should not be counted as valid and should be repeated as age-appropriate 1
• The repeat dose should be spaced after the invalid dose by the recommended minimum interval 1
• This "4-day grace period" does not apply to rabies vaccine due to its unique schedule 1

Accelerated Schedules

• In certain circumstances, accelerated schedules using shorter than recommended intervals may be necessary 1:
  • When a person is behind schedule and needs to be brought up-to-date quickly
  • When international travel is impending
• The ACIP believes the immune response with accelerated intervals is acceptable and will lead to adequate protection 1
• Minimum intervals for accelerated schedules are provided in ACIP guidelines 1

Simultaneous Administration

• Simultaneous administration of all vaccines for which a person is eligible is critical 1
• Administering multiple vaccines during the same visit increases the probability that a child will be fully immunized at the appropriate age 1
• Research shows that approximately one-third of measles cases among unvaccinated but vaccine-eligible preschool children could have been prevented if MMR had been administered at the same visit when another vaccine was administered 1

Common Pitfalls and Challenges

• Certain vaccines produce increased rates of local or systemic reactions when administered too frequently (e.g., adult tetanus-diphtheria toxoid, pediatric diphtheria-tetanus toxoid, and tetanus toxoid) 1
• These reactions are thought to result from the formation of antigen-antibody complexes 1
• Studies show that many children are not vaccinated on schedule despite having sufficient healthcare visits to complete immunizations 2, 3
• Healthcare provider reluctance to administer multiple vaccines simultaneously can contribute to delayed vaccination 4, 5
• Delays in immunization leave children vulnerable to preventable diseases during critical periods 3, 5

Practical Application

• When a child is behind on vaccinations, consult the catch-up immunization schedule for children aged 4 months through 18 years 1
• For children from birth through 5 years of age, an interactive computer-based program is available to assist with catch-up scheduling 1
• Optimal record keeping, maintaining patient histories, and adhering to recommended schedules can decrease the incidence of adverse reactions without adversely affecting immunity 1
• When evaluating vaccination records from other countries, be aware that childhood vaccination schedules vary, particularly for measles vaccine which may be administered at 9 months in developing countries 1