What is the recommended vaccination schedule for a 7-year-old who has not received the varicella (chickenpox) vaccine?

Varicella Vaccination for a 7-Year-Old Child

A 7-year-old child who has never received varicella vaccine should receive two doses of varicella vaccine administered at least 3 months apart, with the second dose acceptable if given as early as 28 days after the first dose. 1, 2

Recommended Catch-Up Schedule

For children aged 7 years (under 13 years) who have never been vaccinated:

• Administer the first dose immediately at the current visit 1, 2
• Schedule the second dose 3 months later as the recommended interval 1, 2
• The minimum acceptable interval is 28 days between doses, though this is not the preferred timing 1, 2
• If the second dose is inadvertently given between 28 days and 3 months, it does not need to be repeated 2, 3

Critical Implementation Points

There is no need to restart the vaccine series regardless of time elapsed - this child simply needs to begin the two-dose series now 1

Both doses should be completed before school entry if possible, as all children entering school should have received two doses of varicella vaccine or have other evidence of immunity 2

Use single-antigen varicella vaccine (Varivax) for this 7-year-old child, as MMRV combination vaccine (ProQuad) is only approved for ages 12 months through 12 years 2, 4

Timing Considerations with Other Vaccines

If MMR vaccine is also needed, you have two options 3:

• Administer both MMR and varicella vaccines on the same day (preferred to avoid delays) 3
• If not given simultaneously, separate them by at least 28 days to avoid interference between live virus vaccines 3

Do not administer MMR and varicella vaccines less than 28 days apart unless given on the same day, as this may result in impaired immune response 3

Rationale for Two-Dose Schedule

Two doses provide significantly superior protection compared to one dose 2, 5, 6:

• Vaccine efficacy: 98% with two doses versus 94% with one dose 2
• Recipients of two doses are 3.3-fold less likely to develop breakthrough varicella compared to one-dose recipients 2, 6
• After two doses, >99% of children achieve protective antibody levels versus 76-85% after a single dose 2
• Two-dose efficacy against moderate to severe varicella is 99.5% 5

One-dose vaccination has proven insufficient to prevent school outbreaks, even with 99% vaccination coverage, as vaccinated children with breakthrough disease can still transmit varicella 6

Common Pitfalls to Avoid

Do not delay vaccination - this child is already behind schedule and at risk for varicella exposure, particularly in school settings where transmission is intense 2, 6

Do not use MMRV vaccine - while approved for children up to 12 years, single-antigen varicella vaccine is appropriate and avoids the higher fever rates associated with MMRV 2, 4

Do not wait longer than necessary between doses - while the 3-month interval is recommended, completing the series promptly is more important than achieving the exact interval 1, 2

Ensure proper documentation of vaccination dates, as only doses with written documentation should be considered valid 2, 4

Priority Justification

This recommendation prioritizes morbidity and mortality reduction by ensuring complete protection against varicella, which can cause serious complications including pneumonia, bacterial superinfection, encephalitis, and death, particularly as children age into adolescence where disease severity increases 4, 5