Family health

Flu shots

We shed light on some common misconceptions about the flu shot

By Wendy Haaf
Flu shots

Should your kids be following suit when you roll up your sleeve for your flu shot each fall? Yes, says the expert panel that guides Canada’s vaccination policies, which recommends immunizing healthy kids against influenza. So, if you’ve got some pointed questions, read on for answers.

Q: Why would my healthy 10-month-old need a flu shot?

A: Influenza can cause major problems, including pneumonia (and, rarely, death) in healthy kids, particularly in this age group. Recent research shows that when it comes to developing serious flu complications, babies from birth to 24 months are on par with seniors, says Jeff Kwong, a physician at Toronto’s Institute for Clinical Evaluative Sciences. Statistics show kids “have a one in 1,000 chance of having to be admitted to hospital due to influenza and about a one in 10 chance of needing to visit an emergency department or a doctor’s office,” he says. In light of this, Canada’s National Advisory Committee on Immunization (NACI) began recommending that healthy babies between six months and two years get vaccinated. All provinces and territories have since added a flu shot to their infant immunization schedule and now pick up the tab for the jab.

Q: What about older kids?

A: Even though kids over two are in a lower risk category than babies, many experts believe routinely immunizing toddlers and school-aged kids is still worthwhile because it cuts down on visits to doctors’ offices and emergency rooms, and lost workdays for parents, and protects younger sibs and relatives. “We recommend people get the flu shot regardless of their age and level of overall health,” says Elizabeth Shaw, a Hamilton family practitioner and spokesperson for the College of Family Physicians of Canada. (Ditto for the Canadian Paediatric Society, which suggests all kids over six months get a yearly flu shot.) “Even if kids don’t end up in hospital, they can get pretty sick with flu, and be down with a fever for the better part of a week.”

 Q: OK, so why not vaccinate my baby before six months?

A: “The thinking is that it’s probably not effective before then because a baby’s immune system isn’t developed enough for this vaccine to work,” Kwong explains. Consequently, it’s doubly important to use other strategies to protect very young infants from catching the infection. That’s one reason the NACI also recommends that expectant moms get vaccinated.

Q: How well does the flu shot work in children?

A: According to the Ontario Ministry of Health, the vaccine is 77 to 91 percent successful at preventing respiratory flu infections in children. True, a few years back, a highly regarded group of scientists concluded it wasn’t clear whether the vaccine was any more effective than a sham shot in children under two. However, recent research suggests immunizing kids under two really does work, notes Joanne Langley, a professor of paediatrics (infectious disease) at Dalhousie University and the IWK Health Centre in Halifax. For instance, one US study of more than 400 babies aged six to 23 months found the recommended two-shot regimen (the required dose in kids under nine who are getting vaccinated against flu for the first time) was 74 percent effective. While more research is still needed, most experts agree there’s enough evidence to support vaccinating the under-two set.

Q: Why do kids need to be vaccinated again every year?

A: Two reasons: First of all, the immunity lasts only long enough to cover the duration of that year’s flu season. Second, the protein “coat” on an influenza virus changes subtly from year to year. Since protection depends on your immune system’s ability to quickly recognize and kill the virus, this “disguise” can allow the germ to slip under the radar and make you sick.

Q: My mother, a nurse, claims that the shot can actually give you the flu. Can this happen?

A: Mom’s mistaken. The vaccine contains only part of the virus — and it’s not live, notes Langley, so there’s no way it can cause infection. And don’t forget: Influenza vaccine only protects against three strains of the infection — not the hundreds of other viruses (such as respiratory syncytial virus or RSV) that cause similar symptoms. (Of course, it goes without saying that the shot also doesn’t ward off the many viruses that cause diarrhea or vomiting — influenza has nothing to do with so-called stomach flu.)

However, a small percentage of children may develop a mild fever for about 24 hours after they’ve been vaccinated, which is essentially just a sign that the immune system has been activated.

Q: Are there any other possible side effects?

A: The most common one is soreness in the arm, which usually subsides within a day. According to Bryna Warshawsky, the associate medical officer of health for the Middlesex-London Health Unit in London, Ont., a flu shot may also cause a very slight increase (about one in one million) in the chance of developing Guillain-Barré syndrome, a neurological disorder that causes (usually temporary) muscle para-lysis. Still, you don’t have to be a math whiz to see how that slim possibility stacks up against the odds of a child ending up seriously ill with the flu.

Q: Are there healthy kids who shouldn’t get immunized?

A: Yes. Since flu vaccine is grown in egg, some kids who are highly allergic to eggs may need to avoid the jab, says Warshawsky. If your child has had a serious allergic reaction to eggs (hives and difficulty breathing, for example), discuss the situation with your doctor: Some kids with this kind of allergy actually can get the shot after evaluation by an allergist. But since such severe egg allergies are quite rare, “a baby doesn’t have to have tried eggs before you give the vaccine,” Warshawsky stresses. Kids who are allergic to another component of the vaccine, such as the antibiotic or preservative used in the vaccine, and those who have had an allergic reaction to a previous dose (also extremely rare) should skip the shot too.

What’s in the flu shot?

Inactivated split influenza virus
The shot contains three strains of flu virus: two from the A family and one B strain. The viruses are grown in egg, then chemically inactivated and broken into bits using detergents. The vaccine is then purified, which removes almost all of the internal parts of the virus and most of the egg.

Depending on the manufacturer, the vaccine may contain small amounts of formaldehyde (which, incidentally, is found naturally in the body), gelatin and thimerosal. A mercury-derived preservative, thimerosal is no longer used in most routine childhood immunizations (hepatitis B is the only other exception) because many parents prefer to avoid the chemical altogether. Ask your doctor if you want to find out more about thimerosal-free vaccines.

This article was originally published on Nov 10, 2008

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