Like most parents, I’ve got my concerns about vaccines. Although I’m a firm believer that vaccines are a life-saving miracle that we’re lucky have, I’m always on the lookout for side effects or signs of a serious reaction after my kids have been vaccinated, and I take steps to make sure my kids are comfortable and well-supervised after getting a shot. So, when I heard parents saying that children can be contagious after getting a chickenpox vaccine (also called VZV or varicella-zoster vaccine), I was a little worried. Was I unintentionally spreading disease by letting my vaccinated children spend time around other kids?
I was pleased with what I found out. As one might expect of playgroup chatter, this concern is mostly unfounded, and based more in parents’ misunderstandings than in actual medical science. Still, it’s important for parents to be aware of the very minimal risk of contagiousness that vaccinated children present to the community. Here are some points to bear in mind.
1. “Wild” chickenpox is extremely contagious. Your child is much, much more of a threat to others, particular people with weakened immune systems, if you skip the chickenpox vaccine and he catches wild chickenpox. An unvaccinated child has a 95% risk of catching chickenpox by simply being in the same room as a child with an active infection. The best way to protect your child and the people around him is to vaccinate. This is true even if vaccines made children mildly contagious, since actual chickenpox is a much bigger threat.
2. Your child is only truly contagious if he gets chickenpox from the vaccine, which is very rare. The Centers for Disease Control notes that, although it only happens very rarely, children can catch chickenpox from the vaccine. That’s because the chickenpox vaccine is made from a live but weakened virus, which will every now and then cause an infection before the child’s immune system learns to produce antibodies in response to it. Chickenpox from the vaccine is much more mild than wild chickenpox and is shorter in duration, but, if your child is one of the very few children who catches the disease from the shot, he will indeed be contagious.
3. Unless someone is handling your kid’s poop and not washing their hands, the odds of them catching chickenpox from your vaccinated kid are minimal. One mistake commonly repeated by anti-vaccine parents is, “Kids are contagious for six weeks after being vaccinated for chicken pox.” This is one example of how a little knowledge can create a big misunderstanding. Studies have found that children can “shed” chickenpox for up to six weeks after vaccination, but the only place where he virus is detectable is in their poo . Assuming you wash your hands and your kids’ hands (and I hope you do!), there is no way that someone will catch chickenpox from your child’s poop.
4. Every now and then, the chickenpox vaccine might cause a rash, which could be contagious in theory. About one child in fifty will develop a mild rash a few days after being vaccinated for chickenpox. It’s important to note that this rash is not chickenpox itself and is not a sign that your child got sick from the vaccine. The rash is very minor and will go away quickly. However, in extremely rare cases, some children with the rash could be contagious. Although there are no known cases of someone catching chickenpox from a post-vaccine rash, it can’t hurt to be cautious if your child gets a rash after getting the vaccine.
5. There are simple precautions you can take. Knowing that an unvaccinated child is a much bigger risk to vulnerable people (like newborns, pregnant women, and people receiving chemotherapy), you’re already helping to protect the people around you by getting your child vaccinated. However, if someone in your family or social circle has a weakened immune system and has not been vaccinated, you can minimize the already-small risk of contagiousness. Dr. Janet R. Serwint advises parents to keep their kids away from immunocomprimised people for a few days if the child develops a rash, simply to be cautious. Of course, it’s always a good idea to wash your hands and your kids’ hands, especially after using the bathroom. And, if your child is one of the extreme few children who catches chickenpox from the vaccine itself, keep her home until she has been completely symptom-free for at least 48 hours. It’s very unlikely that your child will be contagious after receiving the chickenpox vaccine, but it can’t hurt to err on the side of caution if someone around you is at risk.