What is chickenpox?


Infection caused by varicella zoster virus. It causes a rash (small blisters) and make a child generally unwell. Full recovery is usual in children. Once a child get chickenpox it provide lifelong protection.


  • Fever
  • Rash – spots appear in crops. Develop into small blisters which are itchy. The rash starts off like red spots then blisters and scab over.
  • Tiredness, loss of appetite

Some children feel unwell for few days, others appear only mildly ill. Usually get better within a week. The blisters dry up and scab, may take up to 2 weeks to go completely.

Possible complications

  • Skin infection. Some spots can become infected with bacteria. The surrounding skin become red, painful and may be discharging pus. Antibiotics is needed.
  • Scarring of the rash, especially if they are badly scratched
  • Pneumonitis – inflammation of lung
  • Encephalitis – inflammation of brain
  • Shingles – a very delayed complication caused by the same virus. Anyone who has chickenpox in the past may develop shingles. It is because after one have chickenpox, the virus does not go completely but some virus remain inactive in the nerve. Years later for unclear reason, the virus may be reactivated and cause shingles.

When to seek urgent treatment from your child’s doctor?

If your child develop any of the following symptoms:

  • Unable to take fluids due to severe rash in the mouth
  • A severe rash or rash which bruises/ bleeds into the skin (haemorrhagic rash)
  • Severe cough and breathing problem
  • Weakness and becoming wobbly on his feet
  • Drowsiness and increased irritability especially in infants
  • Fits
  • Severe or worsening headache

Chickenpox vaccine

Can protect nearly everyone who get it from catching chickenpox.
It is also called varicella vaccine. The vaccine is made from live but weakened virus. It helps protect children from catching chickenpox and reduce the risk of serious, life threatening complications.

First shot can be given at 12-15 months old.

About 2% of the children who are vaccinated develop a very mild case of chickenpox, usually not more than 5-10 blisters. It is also possible for a person who has been vaccinated to develop chickenpox some point later in life, but the disease is always milder and more rapid recovery. Up to 90% of people who get the vaccine will not catch chickenpox.

Study has shown chickenpox vaccine is not responsible for higher risk of getting shingles.

(Written by Dr. Soong Eileen)

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