What is chickenpox?
- Chickenpox is a highly contagious disease, caused by the varicella-zoster virus.
How is chickenpox spread?
- Chickenpox spreads very easily and quickly from person-to-person.
- It is transmitted through the air or in droplets projected by an infected person who coughs or sneezes. It can also be spread through contact with blisters.
- You can also get chickenpox through having contact with the blisters of someone who has shingles.
- It usually takes 10 to 21 days between exposure to the virus and the onset of chickenpox symptoms.
What are the symptoms of chickenpox?
- The first symptoms of chickenpox are usually fever, runny nose, and fatigue.
- After a day or two, an itchy rash appears. The rash quickly turns into fluid-filled blisters. After about five days, the blisters form scabs.
- The rash may first appear on the face, chest, and back, then spread to the rest of the body including the inside of the mouth, eyelids and genitals.
How long is chickenpox contagious?
- Chickenpox is most contagious one or two days before the rash appears.
- The infected person can continue to transmit the disease until all the blisters have formed a scab.
- In most cases, having had chickenpox once provides immunity for life. However, some people will get chickenpox more than once.
What risk does chickenpox pose to the fetus?
- A chickenpox infection during the first or second trimester of pregnancy can lead to malformation or damage to the fetus called Congenital Varicella Syndrome.
- The syndrome affects about 1 to 2% of babies whose mothers were infected during the first 20 weeks of pregnancy.
What risk does chickenpox pose to the newborn?
- A chickenpox infection that starts during the five days before childbirth up until the two days after childbirth, can result in a severe case of chickenpox in the newborn.
- Chickenpox infections in newborns can cause serious complications, including death.
What if I am pregnant and have been exposed to chickenpox?
- Pregnant individuals should contact their healthcare provider as soon as possible if they have never had chickenpox.
- A simple blood test can determine if you are immune to chickenpox.
- If it is determined that you are not immune, your doctor may give you varicella-zoster immune globulin, which contains a high concentration of antibodies (protective substance in the blood) that can help prevent disease or make it less severe.
Is there a chickenpox vaccine?
- There is a chickenpox vaccine that is given as part of Ontario's childhood immunization program.
- You should not get this vaccine if you are already pregnant.
- Non-pregnant individuals getting the chickenpox vaccine should wait a month before getting pregnant.
- If you are thinking of becoming pregnant, contact your healthcare provider to review your immunity status and discuss vaccinations.
Where can I get more information about chickenpox?
Contact the Communicable Disease Control (CDC) Program at 705-474-1400, or toll-free at 1-800-563-2808, ext. 5229 or email us at cdc@healthunit.ca.
References:
- Ministry of Health (2022). Infectious Diseases Protocol, Appendix 1: Chickenpox (Varicella).
- Public Health Agency of Canada (2026). Canadian immunization guide Varicella chapter.
Created: March 2026, by CDC