Varicella (chicken pox) vaccination: the second dose.
Did you know that the recommendation is to have TWO doses of varicella vaccination, even though there’s only ONE on the routine vaccination schedule?
Varicella zoster (chickenpox) virus
is highly contagious - from approx 48 hours before the rash appears until all lesions have crusted over
is spread by contact with blister fluid and respiratory droplets
has an incubation period of up to 3 weeks (i.e it can take that long to appear after being exposed)
can recur as shingles - after an infection, the virus can lie dormant in part of the spinal cord for many years and later reactivate and cause shingles
is typically bothersome but not severe - though it can rarely be associated with severe complications such as secondary bacterial infection, pneumonia, conditions involving the brain and spinal cord (meningitis, encephalitis, cerebella ataxia and transverse myelitis) and thrombocytopenia (low platelets).
can cause a congenital syndrome in infants if a non-immune person contracts varicella in pregnancy
Varicella vaccination
contains a very small amount of live varicella virus - which helps the bodies to make antibodies to the virus
is effective at reducing serious complications from varicella: there was an almost 70% reduction in hospitalisations from varicella in the 2.5 years after the vaccine was introduced
reduces the risk of getting varicella at all
can have side effects - more common side effects include a fever (high temperature) and redness, pain and swelling at the injection site
can be associated with a mild blistering rash occurring up to 3 weeks after vaccination - this can contain a very small amount of the virus and therefore should be covered to avoid the low risk of transmission of the virus (nb in studies of 56 million children who received the vaccination, this was documented to have occurred 6 times and was mild in the recipient cases)
is very rarely associated with anaphylaxis and with similar complications to the virus itself, though the risk of these occurring is significantly lower than with having the infection itself
is contraindicated for certain people - including pregnant women, people who are severely immunocompromised and those with previous anaphylaxis to the varicella vaccine.
it is safe to have whilst breastfeeding and safe to have even with a history of previous chicken pox
Why 2 doses?
There is evidence that after having only one dose, that immunity to chicken pox can wane somewhat after about 5 years. A second dose has been shown to increase the vaccine effectiveness and longevity, and to reduce the risk of breakthrough infection
When should the 2nd dose be given?
The varicella vaccination on the national immunisation schedule is given at 18 months - it comes in combination with measles, mumps and rubella at this age.
A second dose is usually given as a stand alone vaccination (Ie not a combination one) and can be given any time from 4 weeks- 5 years after this.
It can also be given before 18 months - it is actually recommended to consider varicella vaccination from 12 months of age; especially if there is increased risk of exposure eg from childcare or travel. One brand can in fact be safely from as early as 9 months in certain circumstances (and we chose for our youngest daughter to have a first dose before she starts daycare, even though she’s not yet 12 months old).
As always, it’s important to talk to your healthcare provider about recommendations for your individual child or family.
For more information -
https://www.health.gov.au/topics/immunisation/immunisation-services/chickenpox-immunisation-service
