Is my child protected from chicken pox?
Dear Doctor,
MY friend’s 8-year-old daughter was recently down with chicken pox. My daughter, who is the child’s playmate, has already been vaccinated against the disease. Will she be completely protected or is there a chance she may still get it? I also have a newborn baby at home so I’m worried about him contracting chicken pox. What prevention methods can I take? Kamini Raj, Petaling Jaya
DEAR KAMINI RAJ,
CHICKEN pox is also known as varicella as it is caused by the varicella-zoster virus. It is very contagious and can spread easily from one person to another by touch or through respiratory droplets.
How many doses of chicken pox vaccine did your daughter receive?
A single dose is 85 per cent effective in preventing chicken pox infection. The effectiveness increases to 88-98 per cent after receiving two doses. Therefore, there is still a slight possibility of her contracting the infection.
As the incubation period for chicken pox is rather long — 10-21 days — you need to monitor her closely for any fever or rash.
Your daughter’s playmate will be infectious one to two days before her rashes appear and she will continue to be till all the blisters have formed scabs.
The fact that your daughter has received at least one dose of chicken pox vaccine protects her from a serious chicken pox infection.
If a person vaccinated for chicken pox gets the disease, they can still spread it to others. Our concern now will be her transmitting the infection to your newborn baby.
According to the Centers for Disease Control (CDC) guidelines, the chicken pox vaccine is not recommended for a child under 12 months of age.
Hence, this is not an option for your baby. For babies above a-year old who have never been vaccinated for chicken pox, giving the vaccine within three days of exposure may reduce the infection rate or severity of illness.
During the last three months of pregnancy, antibodies from the mother are passed to her unborn baby through the placenta.
This is known as passive immunity and will last for the first few months after the baby is born. However, if you have never had chicken pox before, the baby will not be protected.
Most older babies are protected from the varicella virus through antibodies that are found in breast milk but only if the mothers have had chicken pox before. If so, continue nursing your baby as much as you can.
Indirect transmission through an immune carrier like your daughter is unlikely. However, if she does contract chicken pox there is still a chance she can transfer it to your newborn. Trying to keep them separated may not be feasible especially when the incubation period is rather long — up to three weeks.
If your newborn starts to develop fever, has reduced appetite or a rash, bring him to see his paediatrician.