Residency · Residency · Medicine Pediatrics
Immunization Across the Lifespan
Overview
Vaccination is one of the greatest public health achievements, preventing an estimated 4-5 million deaths annually worldwide. The Med-Peds physician must master both the pediatric immunization schedule (AAP/ACIP) and adult immunization recommendations (ACIP/ACP) Emerging challenges include vaccine hesitancy, catch-up immunization for under-immunized populations, and new vaccines (RSV, mpox) Bridging pediatric and adult immunization knowledge is a core Med-Peds competency.
Pediatric Immunization Schedule (ACIP/AAP Highlights)
Birth to 6 Months
HepB: dose 1 at birth (within 24 hours); dose 2 at 1 month; dose 3 at 6 months. DTaP: doses at 2, 4, 6 months (primary series); boosters at 15-18 months and 4-6 years. IPV (inactivated polio): 2, 4, 6-18 months, 4-6 years. Hib: 2, 4, (6 months depending on product), 12-15 months. PCV15 or PCV20: 2, 4, 6, 12-15 months. RV (rotavirus): 2, 4, (6 months for RotaTeq/pentavalent); first dose must be given before 15 weeks of age; series must be completed by 8 months.
6 to 18 Months
Influenza: annually starting at 6 months; 2 doses in first season, then 1 dose annually. MMR: dose 1 at 12-15 months; dose 2 at 4-6 years. Varicella: dose 1 at 12-15 months; dose 2 at 4-6 years. HepA: 2 doses starting at 12 months (separated by 6 months)
Adolescent Schedule (11-18 years)
Tdap: single dose at 11-12 years (replaces DTaP; then Td or Tdap every 10 years) HPV: 9-valent (Gardasil 9); start at age 11-12 (can begin at 9); 2-dose series if started before age 15; 3-dose series if started at >= 15 years; up to age 26 (shared decision-making 27-45) MenACWY: dose 1 at 11-12 years; booster at 16 years. MenB: shared clinical decision-making at 16-23 years (preferred 16-18); 2-3 dose series depending on product. COVID-19: per current ACIP recommendations.
<image>Comprehensive pediatric immunization schedule from birth through age 18 showing timing of each vaccine with color-coded bars indicating recommended ages and catch-up windows</image>
Adult Immunization Schedule
All Adults
Influenza: annually for all adults. COVID-19: per current updated formulation recommendations. Td/Tdap: Tdap once if not previously received; then Td or Tdap every 10 years. MMR: 1 or 2 doses if no evidence of immunity (born after 1957); 2 doses for healthcare workers, college students, international travelers. Varicella: 2 doses if no evidence of immunity.
Age-Based Recommendations
| Vaccine | Age Group | Doses | Key Notes |
|---|---|---|---|
| Shingrix (Zoster) | >=50 years (or >=19 if immunocompromised) | 2 doses (2-6 months apart) | Recombinant; safe in immunocompromised |
| PCV20 (or PCV15 + PPSV23) | >=65 years or 19-64 with risk factors | 1 dose PCV20 | Risk factors: immunocompromise, chronic disease |
| HepB | All adults 19-59; risk-based >=60 | 2-3 doses (product-dependent) | Heplisav-B is 2-dose series |
| HPV (Gardasil 9) | Through age 26 (routine); 27-45 shared decision | 2-3 doses (age-dependent) | 2 doses if started <15 years |
| RSV | >=60 years (shared decision); maternal 32-36 weeks | 1 dose | Maternal dose protects newborns |
Zoster (Shingrix): 2 doses for adults >= 50 years; also for immunocompromised adults >= 19 years. Pneumococcal: PCV20 alone OR PCV15 followed by PPSV23 for adults >= 65 or those 19-64 with risk factors (immunocompromise, CSF leak, cochlear implant, chronic disease) HepB: universal vaccination for all adults 19-59; risk-based for >= 60 (Heplisav-B 2-dose series or traditional 3-dose series) HPV: through age 26 (routine); shared decision-making 27-45. RSV: recommended for adults >= 60 by shared clinical decision-making; also maternal RSV vaccination at 32-36 weeks gestation (Abrysvo) to protect newborns.
Special Populations
Pregnancy: Tdap (each pregnancy, 27-36 weeks); influenza; COVID-19; RSV (32-36 weeks, seasonal); HepB if indicated. Immunocompromised: avoid live vaccines (MMR, varicella, live attenuated influenza, oral polio); may need higher doses or additional boosters; Shingrix (recombinant, non-live) IS safe. Asplenic/hyposplenic: pneumococcal, meningococcal (ACWY + B), Hib vaccines essential. Healthcare workers: HepB (confirm immunity with anti-HBs), MMR, varicella, annual influenza, COVID-19, Tdap.
Catch-Up Immunization
Principles
Never restart a vaccine series — resume where left off regardless of interval. Multiple vaccines can be administered at the same visit (different anatomic sites) Minimum intervals between doses must be respected (shorter intervals may not produce adequate immunity) Live vaccines (MMR, varicella) should be given simultaneously or separated by >= 28 days.
Common Catch-Up Scenarios
Under-immunized immigrant/refugee children: obtain records if available; if uncertain, serology can guide (measles, HepB, varicella); otherwise start catch-up schedule. Adolescents without childhood vaccines: follow ACIP catch-up schedule; HPV most commonly missed. Adults with unknown immunization status: check HepB serology; give Tdap, MMR (if born after 1957 without documented immunity), varicella (if no evidence of immunity)
Vaccine Hesitancy
Prevalence and Drivers
Increasing globally; WHO identified vaccine hesitancy as a top 10 global health threat. Drivers: safety concerns (autism myth, ingredient fears), distrust of pharmaceutical industry or government, religious/philosophical beliefs, misinformation on social media, low perceived risk of disease. The autism-MMR link has been thoroughly debunked (Wakefield study was fraudulent and retracted; multiple large studies including >1 million children show no association)
Communication Strategies
Presumptive approach: "Today we will be giving [vaccines]" rather than "Would you like vaccines?" — improves acceptance rates. Motivational interviewing: explore concerns non-judgmentally, reflect back, provide tailored information, respect autonomy. Acknowledge concerns: validate emotions; avoid dismissing fears. Focus on disease risk: share real consequences of vaccine-preventable diseases. Chunk and check: provide small amounts of information, check understanding. Avoid information overload; multiple conversations over time are more effective than a single confrontation.
Practice Policies
AAP supports continued care of families who refuse vaccines (opportunity for ongoing education) Some practices have dismissal policies for persistent refusal; ethically debated. Document refusal, provide AAP "Refusal to Vaccinate" form, and revisit at each visit.
<image>Infographic showing common vaccine myths versus evidence-based facts including MMR-autism, ingredient safety, immune system overload, and natural immunity with corresponding refutation points and key references</image>
Vaccine Safety and Adverse Events
Common Reactions
Local: injection site pain, redness, swelling (most common across all vaccines) Systemic: low-grade fever, irritability, fatigue, myalgias; typically self-limited 24-48 hours. Febrile seizures: associated with MMR (especially MMRV combination) and influenza vaccines; risk is small and seizures are benign without long-term sequelae.
Serious Adverse Events (Rare)
Anaphylaxis: ~1 per million doses; manage with epinephrine; 15-30 minute observation post-vaccination. Intussusception: associated with first-generation rotavirus vaccine (RotaShield, withdrawn); current vaccines have minimal increased risk (~1-5 per 100,000 first doses) GBS: small increased risk after influenza vaccination (~1-2 per million); history of GBS within 6 weeks of influenza vaccine is a precaution. Thrombosis with thrombocytopenia syndrome (TTS): rare complication of adenoviral vector COVID-19 vaccines.
Contraindications vs. Precautions
True contraindications: severe allergic reaction to prior dose or vaccine component; specific live vaccine contraindications in immunocompromised. Precautions: moderate or severe acute illness (defer until improved); pregnancy (avoid live vaccines) NOT contraindications: mild illness, low-grade fever, current antibiotic use, recent exposure to infectious disease, family history of adverse events, prematurity (vaccinate at chronologic age with full doses)
Travel Immunization
Yellow fever: live vaccine; required for travel to endemic areas in sub-Saharan Africa and South America; lifetime validity of International Certificate. Typhoid: oral (live Ty21a) or injectable (Vi polysaccharide) for travel to South Asia, Southeast Asia, Africa. Japanese encephalitis: for travelers spending >= 1 month in endemic Asia. Rabies pre-exposure prophylaxis: for travelers with animal exposure risk, remote areas without access to post-exposure prophylaxis. Meningococcal ACWY: required for Hajj pilgrimage; recommended for sub-Saharan Africa "meningitis belt". HepA: for travel to endemic areas (many adults not vaccinated in childhood) Consult CDC Travelers' Health (wwwnc.cdc.gov/travel) for country-specific recommendations.
<image>World map showing geographic distribution of key travel vaccine recommendations including yellow fever endemic zones, malaria areas, Japanese encephalitis risk regions, and meningitis belt with corresponding vaccine requirements</image>
Clinical Pearls
Premature infants should be vaccinated at chronologic age with full vaccine doses (not adjusted age, not reduced doses) Egg allergy is no longer a contraindication to influenza vaccination; even patients with severe egg allergy can receive any age-appropriate influenza vaccine (including standard egg-based formulations) HPV vaccine prevents ~90% of HPV-related cancers; vaccination before sexual debut provides maximum benefit but remains beneficial after sexual activity begins. Shingrix is a recombinant (non-live) vaccine and can be given to immunocompromised patients, unlike the older Zostavax (live, now discontinued) MMR and varicella vaccines should be given >= 2 weeks before starting immunosuppressive therapy or >= 3-6 months after discontinuation (depending on agent) Nirsevimab (anti-RSV monoclonal antibody) is now recommended for all infants <8 months entering their first RSV season and high-risk infants 8-19 months; it replaces palivizumab for most indications. The best time to vaccinate is now — missed opportunities at clinical encounters are the leading cause of under-immunization.
References
- Advisory Committee on Immunization Practices (ACIP). Recommended Immunization Schedules for Children, Adolescents, and Adults. United States, 2024-2025. CDC MMWR.
- Kempe A, Saville AW, Albertin C, et al. Parental Hesitancy About Routine Childhood and Influenza Vaccinations: A National Survey. Pediatrics. 2020;146(1):e20193852.
- Opel DJ, Mangione-Smith R, Taylor JA, et al. Development of a Survey to Identify Vaccine-Hesitant Parents. Hum Vaccin. 2011;7(4):419-425.
- Hviid A, Hansen JV, Frisch M, Melbye M. Measles, Mumps, Rubella Vaccination and Autism: A Nationwide Cohort Study. Ann Intern Med. 2019;170(8):513-520.
