Administering Multiple Vaccines at a Single Visit
You should administer all vaccines at the first visit—Hexa 4th dose, PCV 4th dose, MMR 1st dose, Varicella 1st dose, Hepatitis A 1st dose, and JEV—because simultaneous administration of all eligible vaccines is critical for ensuring complete immunization and provides timely protection without compromising immune response or safety. 1, 2
Evidence Supporting Simultaneous Administration
The Advisory Committee on Immunization Practices explicitly states that simultaneously administering the most widely used live and inactivated vaccines produces seroconversion rates and adverse reaction rates identical to those observed when vaccines are administered separately. 1, 2
Key Supporting Data:
Clinical trials involving 1,913 children aged 12-15 months demonstrated that vaccines containing varicella administered concomitantly with DTaP, Hib, and hepatitis B vaccines produced comparable seroconversion rates and antibody titers. 2
The immune response to MMR, varicella, and Hib vaccines administered concurrently with pneumococcal conjugate vaccine showed >90% seroconversion for all antigens. 2, 3
MMR and varicella vaccines administered on the same day produce immune responses identical to vaccines administered a month apart. 1, 2
Hepatitis A vaccine administered concomitantly with MMRV and PCV-7 showed 100% seropositivity rates and was non-inferior to non-concomitant administration. 4
Critical Risks of Splitting Vaccines Across Multiple Visits
Approximately one-third of measles cases among unvaccinated preschool children could have been prevented if MMR had been administered at the same visit when another vaccine was given. 1
Delaying vaccines increases the risk of missed opportunities and leaves children unprotected during the interval between visits. 2
Simultaneous administration is particularly critical when uncertainty exists about whether the child will return for future doses. 1, 2
Practical Administration Guidelines
At the First Visit:
Administer all inactivated vaccines (Hexa, PCV, Hepatitis A, JEV) simultaneously with live vaccines (MMR, Varicella) without any interference or safety concerns. 1, 2
Give each vaccine at separate anatomic sites using different syringes. 2
Never mix individual vaccines in the same syringe unless specifically FDA-approved for mixing. 2, 5
Scheduling Subsequent Doses:
Schedule the second MMR dose at least 4 weeks after the first dose (can be given at 3 months). 1, 5
Schedule the second Varicella dose at least 3 months after the first dose for children under 13 years. 1, 5
Schedule the second Hepatitis A dose at least 6 months after the first dose—this cannot be given at 3 months. 1, 5
Important Caveats
Contraindications to Immediate Administration:
Defer vaccination if the child has moderate to severe acute illness with or without fever. 2
Defer live vaccines (MMR, Varicella) if the child has altered immunity, immunodeficiency, or recent receipt of antibody-containing blood products. 2
Defer if severe allergic reaction (anaphylaxis) to any vaccine component has occurred previously. 2
Documentation Requirements:
Document all vaccines administered in the child's permanent medical record. 2
Provide the parent with an updated immunization record. 2
Common Pitfall to Avoid
Do not confuse the 4-week spacing rule for live vaccines—this rule only applies when two live parenteral vaccines are given separately (not simultaneously). 2, 5 Since you're giving MMR and Varicella on the same day, no spacing considerations apply. All inactivated vaccines (Hexa, PCV, Hepatitis A, JEV) can be given at any interval before, after, or simultaneously with live vaccines. 1, 2