The varicella vaccine (Varivax: Sanofi Pasteur MSD Limited) helps protect against chickenpox (varicella zoster), a common and very contagious infection. The chickenpox vaccine is not a part of the routine national childhood schedule. The vaccine contains live attenuated virus, this is chickenpox virus that is altered to become relatively harmless and can be given in adults and in children from 12 months of age. In special circumstances vaccination from age 9 months may be considered.
One dose of chickenpox vaccine (Varivax) is very effective (up to 90%) for around a year. A second dose reinforces and extends immunity. Vaccination is slightly less effective if given after childhood. Additionally, the vaccine can also be given to prevent chickenpox or reduce severity provided it is given within 3 days of contact with someone with chickenpox. There may also be some effect in reducing infection severity if given up to 5 days following exposure.
As a live vaccine the varicella vaccination should not be given to those with a personal or family history of impaired immunity from any cause including underlying medical conditions or treatment that affects immune response, for example, radiotherapy or corticosteroids. Pregnancy, acute febrile illness, active untreated tuberculosis or known hypersensitivity to any of the vaccine constituents (this includes gelatin and the antibiotic neomycin) are other contraindications to vaccination. Pregnancy should also be avoided for 1 month following vaccination. There is also a risk following vaccination of transmitting chickenpox to susceptible high risk individuals – such as those with weakened immunity, pregnant women who have never had chickenpox and new-born babies of mothers who have never had chickenpox - and close contact should be avoided for up to six weeks.
As with all vaccines the clinic staff will advise during the travel consultation on all aspects of the procedure including vaccine dose schedule, contraindications to vaccination, any possible interactions with other vaccines or medicines and the range of possible adverse effects from the specific vaccine and answer any queries. Specifically aspirin and other salicylates should be avoided for 6 weeks after varicella vaccination as this may cause Reye’s syndrome, a rare serious condition that can affect all body organs.
Like all vaccines varicella vaccine can cause side effects, although not everybody gets them. Very rarely an acute severe allergic reaction may occur usually immediately or very soon following vaccination. It may rarely cause convulsions and other neurological disorders, serious skin rashes and bleeding disorders. As the vaccine contains live, though modified virus, it can cause an episode of chickenpox in susceptible children, particularly those with weakened immunity. Possible mild effects are tenderness and redness/rash at the site where the vaccine was given, fever, irritability, fatigue, and upper respiratory symptoms.
The pre-vaccination questionnaire and the product information leaflet provided during the clinic consultation provide further detailed information on Varivax vaccination.