What is Chickenpox?

Chickenpox is a viral infection caused by the varicella zoster virus. It is usually a mild illness but it can cause serious complications especially in the very young, adults and the immune-compromised. 

The early symptoms include fever, lethargy , loss of appetite and headache. followed by a rash 1-2 days later. The rash will then evolved into an itchy, fluid filled blister vesicle rash throughout the body. 

The person is contagious from 1-2 days before the rash appears until the blisters turn into scabs. It is spread from one person to another through respiratory droplets (coughing and sneezing) and via direct contact with the blisters. 

Chickenpox is usually mild but it can cause serious complications like pneumonia, serious skin infection, joint infection , bone infection, brain infection/damage and even death. 

Person who had chickenpox before can develop zoster (shingles) many years later because the virus stays in the body and can be re-activated. 

Vaccination is recommended for those who do not have chicken pox before with effectiveness of 98%.  Most people post vaccination do not get chickenpox. But a minority may still get chickenpox but it will be very mild with fewer blisters, little or no fever and they recover very fast. 

Chickenpox vaccine schedule

Children who had never contracted chickenpox should get 2 doses of varicella vaccine at these ages:

• 1st Dose: 12-15 months of age
• 2nd Dose: 4-6 years of age (may be given earlier but at least 3 months after the 1st dose)

Anyone above 13 years old who have never had chickenpox or received chickenpox vaccine before should get two doses at least 28 days apart.

It can be given together with other vaccines. 

Contraindications to chickenpox vaccine

• anyone who is moderately/severely ill at time of vaccination should delay the vaccination till they recover. 
• People who previously developed serious anaphylactic allergic reaction to the vaccine should not be vaccinated 
• Pregnant women should be vaccinated during pregnancy, they can only be vaccinated post delivery. Women should not get pregnant at least one month post vaccination.
• Immune-compromised patients who are on steroids, cancer patients on cancer treatment and HIV/AIDS patients should consult a doctor before vaccination. 

Side effects of varicella vaccine


Varicella vaccine is very safe , the risk of serious complications is very rare. Reactions likely to occur after 1st dose rather than the second dose. 


Minor side effects include fever ( 1 out of 10), swelling and pain at site of vaccination (1 in 5 ). Moderate side effects like seizure due to fever is very rare. Severe side effects like pneumonia and anaphylactic reaction is also very rare.