The varicella (chickenpox) vaccine is given as a 0.5 mL injection, either subcutaneously (just under the skin) or intramuscularly (into the muscle). Two doses are required for full protection, and the timing between those doses depends on the patient’s age.
Injection Route and What to Expect
The vaccine can be administered either subcutaneously or intramuscularly. For subcutaneous injection, the needle goes into the fatty tissue just beneath the skin, typically in the upper arm or the outer thigh. For intramuscular injection, the needle enters the muscle tissue, usually in the deltoid (upper arm) for older children and adults, or the front of the thigh for infants and toddlers.
The injection itself takes just a few seconds. After receiving the shot, you may be asked to sit in the clinic for about 15 minutes so staff can watch for any rare reactions like fainting, which is more of a concern with the anxiety of getting a shot than with the vaccine itself.
Dosing Schedule for Children
Children receive two doses of the vaccine. The first dose is recommended between 12 and 15 months of age, and the second dose between 4 and 6 years old. The two doses must be separated by at least 3 months.
For the first dose in children younger than 4, the CDC recommends giving the varicella vaccine as a separate shot rather than using the combination MMRV vaccine (which bundles measles, mumps, rubella, and varicella into one injection), unless a parent specifically requests the combination. Starting at age 4, and for all second doses, the MMRV combination vaccine is generally preferred because it means one fewer shot at the visit.
Dosing Schedule for Teens and Adults
Anyone 13 or older who hasn’t been vaccinated or doesn’t have evidence of immunity needs two doses as well. The spacing is shorter for this age group: the two shots should be given 4 to 8 weeks apart, compared to the minimum 3 months for younger children. Each dose is the same 0.5 mL volume regardless of age.
Adults who grew up outside the U.S., who work in healthcare, or who are around young children or immunocompromised people are among those most commonly recommended for catch-up vaccination.
Who Should Not Get the Vaccine
Because the varicella vaccine contains a live, weakened virus, certain groups should avoid it. The most important contraindications include:
- Pregnancy: The vaccine is contraindicated during pregnancy because the effects of the vaccine virus on a developing fetus are unknown. Women who are vaccinated should avoid becoming pregnant for at least one month after each dose.
- Weakened immune systems: People with significantly impaired immunity, whether from conditions like HIV, medical treatments that suppress the immune system, or certain antibody disorders, should not receive the vaccine. The MMRV combination is also contraindicated for people with these conditions.
One common concern that doesn’t actually prevent vaccination: living with someone who is pregnant. Having a pregnant household member is not a reason to skip or delay the varicella vaccine.
Standalone vs. Combination Vaccine
There are two vaccine options that protect against chickenpox. The standalone varicella vaccine (Varivax) covers only chickenpox. The MMRV vaccine (ProQuad) combines protection against measles, mumps, rubella, and varicella in a single shot. Both are given the same way, as a 0.5 mL subcutaneous or intramuscular injection.
The practical difference comes down to the number of needles at a visit. If a child is due for both the MMR and varicella vaccines at the same appointment, giving them as separate shots means two injections. The MMRV vaccine consolidates that into one. For the first dose in children under 4, separate shots are the default recommendation. For the second dose at any age, or the first dose at age 4 and up, the combination is typically the preferred choice.
Preparation Before Injection
The varicella vaccine is a live virus vaccine that comes as a freeze-dried powder and must be mixed with a liquid diluent right before use. This reconstitution step is handled by the healthcare provider at the clinic. Once mixed, the vaccine needs to be used promptly, as it loses potency relatively quickly at room temperature. None of this preparation requires anything from the patient, but it does mean the vaccine can’t simply be drawn from a pre-filled vial the way some other shots can.