What to do if a 3 month or 3 year old child has not received any vaccinations, including Measles, Mumps, and Rubella (MMR) vaccine and Oral Poliovirus Vaccine (OPV)?

Catch-Up Vaccination for Unvaccinated Children

For an unvaccinated 3-month-old or 3-year-old child, immediately initiate the age-appropriate catch-up vaccination schedule without delay, as there is no need to restart a vaccine series regardless of time elapsed between doses, and delaying vaccinations leaves children vulnerable to preventable diseases during their most susceptible period. 1

For a 3-Month-Old Infant

Immediate Vaccinations Needed

• Hepatitis B vaccine (HepB): Administer the first dose immediately if not given at birth 1
• Diphtheria, tetanus, and pertussis (DTaP): First dose can be given starting at 6 weeks of age 1
• Inactivated poliovirus vaccine (IPV): First dose (minimum age 6 weeks) - note that IPV has replaced OPV in the United States 1, 2
• Haemophilus influenzae type b (Hib): First dose starting at 6 weeks 1
• Pneumococcal conjugate vaccine (PCV): First dose starting at 6 weeks 1

Critical Timing Considerations

• MMR vaccine cannot be given yet - minimum age is 12 months 1, 3, 2
• Multiple vaccines can and should be administered simultaneously at different anatomic sites to accelerate catch-up 1, 4
• Schedule follow-up visits at 4-week intervals to rapidly complete the primary series 1

For a 3-Year-Old Child

Immediate Vaccinations Needed (All Can Be Given Simultaneously)

• MMR vaccine: Two doses needed, with minimum 4-week interval between doses 1, 3, 2
• Varicella vaccine: Two doses needed, at least 3 months apart for children under 13 years 1
• DTaP vaccine: Complete the 3-dose primary series if not previously vaccinated 1
• IPV vaccine: Complete the series (not OPV, which is no longer used in the US) 1
• Hepatitis B vaccine: 3-dose series 1
• Hepatitis A vaccine: 2 doses at least 6 months apart (minimum age 12 months) 1
• Haemophilus influenzae type b (Hib): May need catch-up doses depending on previous vaccination history 1
• Pneumococcal vaccine: Catch-up doses as needed 1

Vaccination Strategy for 3-Year-Old

• First visit: Administer MMR dose 1, varicella dose 1, DTaP, IPV, hepatitis B, and any other needed vaccines simultaneously 1, 3, 4
• 4 weeks later: Administer MMR dose 2 (minimum interval is 4 weeks) 1, 3, 2
• 3 months after first varicella dose: Administer varicella dose 2 1
• Continue catch-up schedule for remaining vaccines with appropriate intervals 1

Critical Principles for Catch-Up Vaccination

No Need to Restart Series

• There is no need to restart a vaccine series regardless of the time that has elapsed between doses - simply continue where the child left off 1
• Use minimum intervals between doses when accelerating catch-up schedules 1

Simultaneous Administration

• Multiple vaccines can be administered simultaneously at different anatomic sites without compromising immune response 1, 4
• Studies demonstrate that DTaP, MMR, and OPV (now IPV) can be safely given together at 15 months with no interference in antibody response 4
• Simultaneous administration is strongly preferred to minimize delays and improve adherence 5, 6

Regarding OPV vs IPV

• The United States now uses IPV exclusively, not OPV 1
• If a child received OPV in another country, a total of 4 doses should be administered if both OPV and IPV were part of the series 1
• For an all-IPV series, a fourth dose is not necessary if the third dose was given at age ≥4 years 1

Common Pitfalls to Avoid

Do Not Delay Catch-Up Vaccination

• More than 1 in 3 US children are undervaccinated for more than 6 months during their first 24 months of life 7
• Delays in immunization have potentially serious health consequences, leaving children vulnerable during their most susceptible period 5
• Only 63% of children follow the recommended schedule, with 37% following alternate or unclassifiable patterns 6

Few True Contraindications Exist

• Minor illnesses with or without fever do not contraindicate vaccination 1
• Severe immunosuppression is a contraindication for live vaccines like MMR 1, 2
• Do not accept parental reluctance to give multiple vaccines in one visit as a reason to delay - this is a significant cause of delayed vaccination 5

Maximize Every Visit

• A delay in one vaccine produces a domino effect if catch-up adjustments are not implemented aggressively 5
• Use combination vaccines when possible to reduce the number of injections and improve adherence 5
• Generate reminders through computerized healthcare records to ensure follow-up 5

Documentation Requirements

• Maintain documentation of all vaccinations in the patient's permanent medical record 3, 8
• Verify immunity through documentation of receipt of vaccines or laboratory evidence 3