Hepatitis B and Varicella Vaccines Can Be Administered on the Same Day
Yes, hepatitis B vaccine and varicella vaccine can and should be administered simultaneously on the same day. 1, 2
Evidence Supporting Simultaneous Administration
Guideline Recommendations
The Advisory Committee on Immunization Practices (ACIP) explicitly states that inactivated vaccines (like hepatitis B) can be administered either simultaneously or at any time before or after live vaccines (like varicella) without interference. 1
The ACIP recommends that simultaneously administering all vaccines for which a person is eligible is critical for ensuring complete immunization at the appropriate age. 2
There are no timing restrictions or spacing requirements between inactivated vaccines (hepatitis B) and live vaccines (varicella) when given on the same day. 2, 3
Clinical Trial Evidence
A 2023 randomized controlled trial (n=450 children) demonstrated that co-administration of varicella vaccine with hepatitis A vaccine (another inactivated vaccine like hepatitis B) achieved non-inferior immunogenicity, with seroconversion rates of 91.79% for varicella and 99.48% for hepatitis A. 4
A 2004 study (n=822 children) showed that concomitant administration of varicella vaccine with other vaccines including hepatitis B-containing combination vaccines resulted in satisfactory antibody responses: 93.2-94.6% for varicella and 99.2-100% for hepatitis B surface antigen. 5
Clinical studies consistently demonstrate that simultaneous administration produces seroconversion rates and adverse reaction rates similar to separate administration. 2, 5, 4
Practical Administration Guidelines
Injection Technique
Administer each vaccine at separate anatomical sites using different syringes. 2, 6
Hepatitis B vaccine should be given intramuscularly (typically 0.5 mL). 3
Varicella vaccine should be administered subcutaneously (0.5 mL). 2, 6
Never mix vaccines in the same syringe unless specifically FDA-approved for mixing. 1, 2, 3
Clinical Benefits
Simultaneous administration increases the likelihood of complete vaccination and provides timely protection, particularly important if there is uncertainty about whether the person will return for future doses. 2, 3, 6
Research shows that approximately one-third of measles cases among unvaccinated preschool children could have been prevented if vaccines had been administered simultaneously during previous visits. 2, 6
Important Caveats
Key Distinction to Avoid Confusion
The 4-week spacing rule only applies when two live parenteral vaccines are given separately (not simultaneously). 1, 2
Since hepatitis B is an inactivated vaccine, no spacing considerations apply with varicella vaccine regardless of whether they are given together or apart. 1, 2
Do not confuse the live-to-live vaccine spacing rule with inactivated-to-live administration—this is a common pitfall. 2
Contraindications to Consider
Defer varicella vaccination if the patient has moderate to severe acute illness, immunodeficiency conditions, severe allergic reactions to vaccine components, or recent receipt of antibody-containing blood products (which may affect varicella vaccine response). 2, 6
Hepatitis B vaccine has minimal contraindications beyond severe allergic reaction to vaccine components. 3