Chickenpox (Varicella)

What is chickenpox?

Chickenpox, also known as varicella, is a highly contagious disease caused by the varicella-zoster virus (VZV). Chickenpox is endemic in Singapore and can affect all ages.

How is chickenpox transmitted?

Chickenpox is primarily transmitted through inhalation of infectious respiratory particles when an infected person coughs or sneezes. It can also be spread indirectly when a person touches a contaminated surface (e.g. doorknob, utensils) or through direct contact, such as touching contaminated hands resulting in direct contact with fluid from blisters.

The incubation period is typically 14 to 16 days, ranging from 10 to 21 days.

What are the symptoms of chickenpox? 

Chickenpox in healthy children is generally a mild and self-resolving illness.

Common symptoms of chickenpox include:

• An itchy rash which progresses to become blisters

• Fever

• Fatigue

Chickenpox infection can lead to complications, particularly pneumonia (lung infection), encephalitis (inflammation of the brain) and bacterial skin infections. In pregnant women, the infection poses greater complications. During early pregnancy (weeks 8 to 20), infection may cause developmental abnormalities in the baby. If the infection occurs later in pregnancy or around birth, complications can include severe infection in the newborn.

What are the risk factors?

Persons who are partially vaccinated or unvaccinated are at risk of infection.

How is chickenpox treated?

There is no specific treatment for chickenpox. Patients are given symptomatic treatment which focuses on relieving the symptoms. This can include using calamine lotion or taking oatmeal baths to soothe the itching, and using acetaminophen to reduce fever. Children with chickenpox should not receive aspirin because of the possibility of a complication called Reye’s syndrome, which is a very serious illness that can cause liver and brain damage and death.

For those who are more likely to develop severe illnesses, there are antiviral medications that can be used to treat chickenpox. These are usually most effective when taken within the first 24 hours of developing the illness. They reduce the severity and duration of the disease, as well as reduce the likelihood of complications. 

How to prevent chickenpox?

Vaccination is the most effective preventive measure for chickenpox. The chickenpox vaccine is recommended under the National Childhood Immunisation Schedule (NCIS) and National Adult Immunisation Schedule (NAIS).

 Other preventive measures: 

• Practise good personal hygiene at all times.

• Wash your hands regularly with soap, especially before handling food or eating, after going to the toilet, or when hands are dirty.

• Avoid touching your face, including eyes, nose and mouth with unwashed hands.

• Avoid sharing of food/drinks or eating utensils.

• Keep the rash/blisters covered and avoid touching them to prevent the infection from spreading to others. 

Please refer to Health advice for travellers for the full list of precautions to take when travelling.