Family health

Vaccine Update

What's rumour, what's real about immunizing your child

By Wendy Haaf
Vaccine Update

The saying “an ounce of prevention is better than a pound of cure” was never more apt than when it comes to vaccine-preventable diseases. Polio, which once paralyzed thousands of Canadians, has been virtually wiped out within our borders, and cases of serious illness caused by Haemophilus influenzae type B (once the number one cause of spinal meningitis in Canadian kids) have dropped by 98 percent, thanks to the Hib shot. “Immunization is by far the most cost-effective health procedure that can be done, in terms of cost per lives saved,” says Robert Bortolussi who is chair of the Canadian Paediatric Society (CPS) infectious diseases and immunization committee.

However, many parents hold misconceptions about how these medical marvels work. For example, an Ottawa-based study revealed that 42 percent of the parents whose kids hadn’t received the flu shot believed it could cause a flu-like illness (it can’t). Here, we clear away some of the confusion about childhood vaccines.

Do vaccines weaken the immune system?
As far as doctors can tell, they don’t undermine it. Our immune systems are designed to handle multiple antigens (foreign viruses, bacteria and proteins) at the same time. For instance, in the average day, a baby may take in far more antigens than those found in childhood shots by mouthing toys and eating food. Also, as vaccine technology improves (newer generation vaccines contain more refined antigens than earlier versions), they’re less likely to cause side-effects like fever.

While some critics claim there’s a connection between vaccination and the surge in asthma rates, “researchers who have looked at immunizations and asthma haven’t found any link,” says Michael Kramer, scientific director of the Institute of Human Development, Child and Youth Health. While more research is arguably needed, diet and exposure to germs and parasites — which have also changed over the past 20 or 30 years — are more likely culprits in the increase of asthma.
What are the standard vaccines my child should get?
Today, babies across Canada are routinely immunized against diphtheria, pertussis (whooping cough) tetanus, polio, Haemophilus influenzae type B (Hib), measles, mumps, and rubella. Also, varicella (chicken pox), meningococcal and pneumococcal vaccines, which parents had to pay for not long ago are now covered by public health programs. All are given during infancy — except in Manitoba, where kids get the meningococcal vaccine in grade four. In BC, New Brunswick, PEI, the Northwest Territories, the Yukon, and Nunavut, babies are also vaccinated against Hepatitis B; children in other provinces get the shot in grade school.

Why should my child get vaccinations? Isn’t she protected if everyone else is immunized?
First, some of the diseases we vaccinate against aren’t caused by bugs we catch from other people, Bortolussi notes. For instance, the bacteria that produces tetanus-causing toxins are found in soil and dust. Secondly, many vaccine-preventable diseases, such as measles, still circulate elsewhere in the world — so all it takes is for one traveller to unsuspectingly bring the bug into Canada and an outbreak can occur, particularly among groups that don’t practise immunization. “That’s why you have these outbreaks in some of the religious or philosophical groups that object to vaccines,” Kramer explains. To keep a disease from spreading, a high percentage of people — about 95 percent in the case of measles — must be immunized. When vaccination rates are lower, the illness can spread, as happened recently in England with a measles outbreak due to low MMR immunization rates.

Why has a whooping cough booster for 14- to 16-year-olds been added to the routine childhood immunization schedule?
“There have been some outbreaks of pertussis, or whooping cough, apparently because the vaccines adults and teenagers received when they were little kids are no longer protecting them against it,” Kramer explains. While the disease usually isn’t life-threatening in teens, the resulting cough is sometimes severe enough to induce vomiting and seems to linger forever. Moreover, adults and teens can infect babies who haven’t been fully immunized. “It can be fatal in infants,” Kramer observes. Consequently, the National Advisory Committee on Immunization (NACI) and the CPS now recommend 14- to 16-year-olds be re-inoculated to protect themselves and any babies they encounter. Teens get a combined shot for diphtheria, tetanus, and pertussis, which contains a newer-generation pertussis vaccine that is considered more effective and causes far fewer side effects.

Should infants get flu shots?
Babies face a higher risk of complications from flu than older kids, even sometimes requiring hospitalization. That prompted the NACI and the CPS to recommend the flu shot be added to the routine immunization schedule for healthy children between six and 23 months old. Some professionals have criticized this decision, since British researchers found no studies supporting the claim that immunization prevents kids younger than two from getting the flu.

However, some research indicates the shot does boost immunity in the under-two set, according to Theresa Tam, director of the immunization and respiratory infections division of the Public Health Agency of Canada (PHAC) in Ottawa. She says in a number of studies (which admittedly involved relatively few children under two), “when we looked at just the six- to 23-month-olds, there was still evidence the vaccine is effective at producing antibodies.”

In the meantime, the flu shot appears to be safe for kids aged six to 23 months: When researchers followed the first group of babies immunized after the recommendation was initially put in place, they didn’t find any serious side effects, just the usual, such as soreness at the shot site and mild fever. Incidentally, the CPS and some other health experts also support an annual flu shot for kids over two years old.

Why has Canada switched to thimerosol-free vaccines?
Some people assume the switch was related to the preservative, which contains minute amounts of mercury and was thought to increase the risk of autism. However, the immunization/autism rumour is like one of those movie zombies that won’t die no matter how many shattering blows it takes. “The evidence is pretty strong that there’s no association between thimerosol and any adverse effect, in particular, autism,” Kramer stresses. In fact, a 2006 Canadian study was the latest research to debunk the connection: McGill researchers discovered autism rates actually rose after thimerosal-containing vaccines were phased out. Nonetheless, when mercury-free vaccines became available, many parents and doctors wanted to avoid unnecessarily exposing kids to the chemical. Consequently, the flu shot is now the only routine childhood jab that contains it, but vaccine manufacturers in Canada are working to develop a thimerosol-free alternative.
The US has recommended babies receive a vaccine against common cause of diarrhea. Will it be adopted in Canada?
Rotavirus is a common cause of diarrhea in kids, and the oral vaccine against it, which must be given to babies before three months of age, has been approved in Canada. But, the need for its use is under active review by Canadian experts, says Elizabeth Ford-Jones, training program director of paediatric infectious diseases at Toronto’s Hospital for Sick Children and a spokesperson for the CPS. The additional information will help determine if it’s needed for Canadian children.

Ford-Jones is lukewarm about the need for this immunization in Canada. Why? Rotavirus is only one cause of childhood diarrhea, involved in about 15 to 20 percent of cases. And while rotavirus-related dehydration kills hundreds of thousands of babies in less developed countries, that’s virtually unheard of here. That said, the vaccine seems to be very effective, and other doctors like Bortolussi acknowledge that it will have major impact in the developing world where access to clean water can be difficult.

Should some children not get immunized?
Kids who have experienced a severe allergic reaction to a particular vaccine (which is uncommon) shouldn’t receive another dose. And children who are allergic to gelatin or the antibiotic neomycin should avoid shots containing them, such as measles and varicella vaccines. As a rule, kids whose immune systems are severely compromised (for example, those receiving certain cancer treatments) shouldn’t get live-virus vaccines, like rubella — however, it is safe for kids with HIV who are otherwise healthy. Children with a mild illness like a cold can receive immunizations, but you should delay shots if a child is moderately or severely sick.

Can some shots be given without a needle?
Today, it is possible to bolster the body’s ability to fight off some infections without getting jabbed. In the US, there is a pneumococcal vaccine given as a nasal spray, but no word yet on when it will be available in Canada. However, a new formulation that can be refrigerated instead of frozen could make the needle-free vaccine cheaper and easier to distribute, eliminating one of the reasons it hasn’t been more widely adopted. “The technology is very promising,” says Tam, “and there may be other vaccines that people will look at delivering through the nose. I think it’s very exciting that, on the near horizon, we’re going to see a number of new vaccines and new vaccine technologies.”

The Straight Dose on Girls and HPV Vaccine
Most, if not all, cases of cervical cancer can be traced to a symptom-less sexually transmitted infection called human papillomavirus or HPV, which about 75 percent of women pick up at some point in their lives. Normally, the immune system evicts the potential troublemaker; however, in some women the virus lingers, eventually triggering precancerous changes in the cervix.

The new vaccine, Gardasil, protects against four sub types of HPV. Studies suggest three doses of Gardasil given over six months prevent 95 to 100 percent of infections from these specific viruses — but only if they’re given before an individual is exposed. So it’s ideal for a girl to get immunized before she’s even thinking about becoming sexually active, which is why the Society of Obstetricians and Gynaecologists of Canada (SOGC) recommends the shot for girls and women ages nine to 26. Considering some parents’ concern that the vaccine will encourage sexuality in young girls, Donald Davis, president of the SOGC, says:“We don’t expect our kids to go out and look for measles, but we do immunize them against that." There are no plans at this time to immunize boys.

While the HPV vaccine has been approved by Health Canada, it’s not currently included in routine immunization schedules. If you want your daughter to get the shot, your doctor will have to prescribe it and you will have to pay about $135 for each of the three doses.

New Vaccine Offers Greater Protection Against Meningitis
Meningococcal bacteria (or Neisseria meningitidis) causes life-threatening problems like meningitis and blood infections. And even with the best care, about 10 percent of those affected will die, and another 10 percent will endure a permanent reminder like hearing loss, neurological damage or an amputated limb.

In the past, meningococcal vaccines either offered long-term protection against one strain, C (which causes about 25 percent of cases of disease), or short-term defence against strains A, C, Y and W-135 (which causes about 60 percent of cases). Recently, a broader, more durable shield against this scary disease has been created: The Menactra vaccine protects against multiple strains of the meningococcal bacteria and is “conjugated,” which means a protein is attached to the sugar in the vaccine giving longer-lasting immunity. According to Dion Neame, medical advisor for the Meningitis Research Foundation, Menactra is the best of both worlds.

This article was originally published on Apr 05, 2007

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