What vaccinations are necessary for a 9-month-old child with no prior vaccinations?

Vaccination for a 9-Month-Old Unvaccinated Child

For a 9-month-old child with no prior vaccinations, initiate DTaP, Hepatitis B, IPV (or OPV where available), Hib, PCV, and BCG (if indicated by local epidemiology), but do NOT give measles vaccine until 12 months of age.

Core Vaccines to Administer at 9 Months

DTaP (Diphtheria, Tetanus, Pertussis)

• Begin the DTaP series immediately with the first dose, as the minimum age for DTaP is 6 weeks 1
• The child will need a 3-dose primary series at minimum 2-month intervals, followed by boosters at 15-18 months and 4-6 years 1, 2
• DTaP protects against immediate risks of pertussis (whooping cough), which carries significant morbidity and mortality in infants 3

Hepatitis B Vaccine

• Administer the first dose of the 3-dose HepB series 1
• Although ideally given at birth, unvaccinated children should receive the series at any age with doses at 0,1-2 months, and 6-18 months after the first dose 1
• This protects against lifelong hepatitis B infection and its complications including cirrhosis and hepatocellular carcinoma 3

Poliovirus Vaccine (IPV or OPV)

• Start the polio vaccine series with either IPV (preferred in most settings) or OPV where it remains in use 1
• The minimum age is 6 weeks, and a 4-dose series is recommended 1, 2
• IPV eliminates the risk of vaccine-associated paralytic poliomyelitis (VAPP) that can occur with OPV 4

Haemophilus influenzae type b (Hib)

• Initiate the Hib vaccine series, which requires 2-3 primary doses depending on the vaccine brand used 1
• For children 7-11 months, two doses given 2 months apart are needed, followed by a booster at 15 months 1
• Hib vaccine prevents invasive bacterial disease including meningitis and epiglottitis 3

Pneumococcal Conjugate Vaccine (PCV)

• Begin the PCV series with catch-up dosing appropriate for age 1, 2
• PCV protects against pneumococcal pneumonia, meningitis, and bacteremia 3

BCG (Bacillus Calmette-Guérin)

• BCG should be given if indicated by local tuberculosis epidemiology 5
• In high TB-burden countries, BCG is typically given at birth, but can be administered later if missed 5

Vaccines to DEFER Until 12 Months

Measles-Containing Vaccine (MMR)

• Do NOT administer measles vaccine at 9 months - the minimum age is 12 months 1
• Measles vaccine given before 12 months has reduced immunogenicity due to maternal antibodies and shows faster waning of immunity over time 6
• While early MCV1 at 5-8 months shows initial immune response, children have lower measles antibodies 3-7 years later compared to those receiving routine MCV1 at 12 months 6
• Wait until 12 months of age to give the first MMR dose, then administer a second dose at 4-6 years 1

Why Option C is INCORRECT

Option C (DTaP, measles, BCG, Hep B, OPV) is incorrect because it includes measles vaccine at 9 months, which violates the minimum age requirement of 12 months 1. The other vaccines listed (DTaP, BCG, Hep B, OPV) are appropriate.

Why Other Options Are Incomplete

• Option A (DTaP, BCG) omits critical vaccines including Hepatitis B, polio, Hib, and PCV 1, 2
• Option B (DTaP, BCG, IPV, OPV) includes both IPV and OPV unnecessarily, and omits Hepatitis B, Hib, and PCV 1
• Option D (DTaP, measles, MCV4, OPV) incorrectly includes measles at 9 months and MCV4 (meningococcal vaccine), which has a minimum age of 2 years 1

Critical Implementation Points

• Administer all appropriate vaccines simultaneously at separate anatomic sites to accelerate catch-up 2
• Follow minimum intervals between doses: typically 4 weeks for most vaccines, though 2 months is optimal for DTaP 1
• Document all vaccinations carefully and provide a catch-up schedule for remaining doses 1
• Prioritize completion of the primary series before the child reaches 18-24 months to ensure protection during the highest-risk period 3, 7

Common Pitfall to Avoid

The most critical error would be administering measles vaccine before 12 months of age based on the child being "behind schedule." Resist the temptation to give measles vaccine early - the reduced immunogenicity and faster waning of immunity make waiting until 12 months the evidence-based approach 6.