What is varicella?

Chickenpox, also known as varicella, is a highly contagious disease caused by the infection with the varicella zoster virus. After being infected through droplets or contact, it will cause red rash, blisters, itching, fever and fatigue, and even lead to pneumonia, encephalitis and other fatal diseases.

Timing of vaccination

• Routine vaccination schedule for children: A single-dose live-attenuated vaccine should be injected.
• Inoculation at 12 months of age.
• The second dose can be administered to preschoolers at the age of 4-6 at one’s own expense to improve the protective effect.

Conditions not suitable for vaccination

• Fever, acute moderate to severe illness.
• Severe allergic reaction to any component of the vaccine.
• Severe immunodeficiency (including severe immunodeficiency in HIV-positive patients, those with congenital immunodeficiency syndrome and leukemia, lymphoma and other malignancies or those on chemotherapy, immunosuppressive drugs and high doses of steroids).

Precautions

• If the chickenpox vaccine is not administered simultaneously with other live attenuated vaccines (e.g. BCG, MMR, live attenuated Japanese encephalitis vaccine), the interval should be at least 28 days.
• The use of salicylates should be avoided within 6 weeks after varicella vaccination in children under 18 years old.
• Women should avoid pregnancy for 4 weeks after vaccination.
• People with red rash after inoculation should avoid contact with those with severe immunodeficiency, so as not to infect others.
• Those who have received specific antiviral drugs within 24 hours before vaccination should start taking them again 14 days after vaccination.

Vaccination interval after the administration of immunoglobulin and blood transfusion

• People who have received an intramuscular injection of immunoglobulin or hepatitis B immunoglobulin (HBIG) should be vaccinated at an interval of 3 months.
• People who have received blood transfusion or intravenous blood products should be inoculated 6 months later.
• Those having received intravenous infusion of high-dose (≧1g/kg) immunoglobulin are advised to take the vaccine at an interval of 11 months.

Possible adverse reactions after vaccination

• Local reactions such as redness, pain or swelling may occur at the site of inoculation.
• Mild fever, accompanied occasionally by high fever and convulsions.
• Blisters similar to varicella may appear at the injection site or body 5 to 26 days after inoculation.
• Like natural varicella infection, the vaccine virus may lurk in the body. When the immune function is low, the virus reactivates and becomes herpes zoster, but its incidence and symptoms are lower than those of natural infection.