Q Can my child get a vaccine when she’s running a fever? What if she has a cold virus?

A Vaccines are without a doubt one of the most important and effective health advances of the last century. They safely and effectively prevent many very serious
diseases. It’s crucial that every child and adult remain vigilant and up to date on vaccines, both to protect themselves and their communities.

However, it’s also important that vaccines be given when they’re safe and effective. Yours is a good question-should vaccines be given to a child who is ill? Could that make the vaccine less effective, or could that make it more likely that the child will have a negative reaction to the vaccine?

Many good studies have looked at that issue. As far as safety goes, minor illnesses like the common cold, with or without fever, don’t make vaccines less safe. Children are not more likely to have a serious
reaction to vaccines when they’re ill. However, from a practical point of view, it’s sometimes a good idea to delay vaccines in a sick child, with or without fever. That’s because it may be difficult after the vaccine to know if worsening symptoms are caused by the pre-existing illness, or from a reaction to vaccines. I’m more likely to suggest delaying vaccines if a child has a more serious illness, or if the parents are especially worried that the child could become more ill.

In most cases, vaccines given to children with mild illnesses are just as effective. Some potential exceptions include using the “Flumist” nasal squirt vaccine in a child with nasal congestion from the common cold. It’s possible that the nasal squirt may be less effective if the nose is all stuffed up to begin with. Also, oral vaccines (including the rotavirus vaccine) should probably not be given to a baby with vomiting, because it might just come back up. Injected vaccines don’t have these limitations.

When deciding whether to delay vaccines, it’s also important to consider if the child is already behind
vaccination schedule, or if the child is likely to end up far behind because of minor illnesses. For instance, babies in daycare get, on average, 8-10 viral colds every year-and most of these occur during the winter months. That means that daycare kids at checkups seem to always have at least some cold symptoms. And these are the children with the most exposures, who really need to stay current on their vaccines! It is not a good idea to routinely delay vaccinations for babies, even if they get frequent colds. Even if the vaccines cause a little fever or temporary increased fussiness, that risk is far outweighed by the risk of serious and potentially deadly disease that spreads when babies are late for immunizations.

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Send your questions to QandA@pedsforparents.com or Pediatrics for Parents, PO Box 219, Gloucester, MA 01931. Please keep them general in nature as we can’t give specific advice nor suggest treatment for your child. All such questions should be asked of your child’s doctor.

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From issue: 28/01-02