Immunization

Frequently Asked Questions About Childhood Immunizations

1. Why are childhood vaccines still necessary? Haven't most of these diseases already disappeared?

Although many vaccine preventable diseases are not seen very often in Canada, some of them such as diphtheria and polio still exist in other parts of the world. Today, with so many more people traveling to places around the world, many of these diseases are really only a plane ride away. Unless a disease has completely disappeared in every place in the world, there is still a risk for outbreaks and epidemics to occur. That is why it is so important that children receive their routine immunizations and for adults to keep their immunizations up to date.

2. Do vaccines really work?

Vaccines really do work! Countries that have had successful immunization programs have seen large declines in vaccine preventable diseases. On the other hand, when countries have had a decrease in immunization rates, they have seen a definite rise in the rates of diseases and in the deaths that occur from these diseases.

3. Is it possible to catch the illness that you are vaccinating against from the vaccine itself?

Purified vaccines (such as diphtheria and tetanus toxoids, Haemophilus b, acelluar pertussis, pneumococcal, meningococcal, and hepatitis b vaccines) and inactivated vaccines (such as inactivated polio and influenza vaccines) cannot cause the diseases they vaccinate against because they do not contain any live germs in them.

Some vaccines such as the measles, mumps, and rubella vaccine (MMR) and the varicella vaccine (chickenpox) are called live attenuated vaccines. These vaccines contain live viruses that have been weakened enough that they can trigger immunity without causing a full-blown infection in the body.

4. Is it possible that all of the vaccines that children receive today can "wear out" the immune system?

The human immune system (even a baby's) is very complex and has the ability to respond to repeated stimulation. In fact, scientists' estimate that infants are able to respond to about 10 000 foreign substances at one time. The body sees vaccines as foreign substances so, "wearing out" the immune system by giving routine childhood immunizations is not possible.

5. How will my child feel after getting immunization shots?

With most childhood vaccines it is not uncommon for a child to experience symptoms like a mild fever, and soreness and/or redness at the injection site. After getting a shot for measles, mumps, and rubella (MMR), some children may develop a measles-like rash all over their bodies within 7 - 10 days. This rash is not harmful or contagious and will disappear within a few days.

6. Can vaccines cause seizures?

Vaccines can cause fever, and fever can cause seizures. These types of fever- related seizures are known as "febrile seizures" and occur in a very small number of children-often children whose parents or siblings have had febrile seizures. Fever from any cause can trigger febrile seizures in 3% of healthy children, so the number of children who would experience febrile seizures following vaccination would be very low. Febrile seizures do not cause brain damage.

7. Can the measles, mumps, and rubella vaccine (MMR) cause autism?

There is no scientific evidence to link the MMR vaccine with autism. Children receive vaccines regularly in their first 18 months of life. This is usually when signs of autism tend to appear in children, so some people have thought that vaccines cause autism. This is not the case. Many studies have been done to determine if there is a link between the MMR vaccine and autism, and a link has not been found.

8. Can the pertussis vaccine cause brain damage?

The original pertussis (whooping cough) vaccine was made from killed bacteria and was sometimes blamed for causing brain damage in infants and young children. Many studies on the pertussis vaccine have been conducted and there has been no proof that it caused brain damage.

In 1997 a new version of the vaccine called acellular pertussis was introduced in Canada. This vaccine produces fewer side effects than the original whole cell vaccine because it is made from chemically purified pertussis proteins, rather than dead intact bacteria.

9. When should vaccination be delayed?

If at the time of vaccination your child is ill, vaccination should be delayed until your child is better. However, minor illnesses such as coughs or colds, or a low-grade fever (39-39.5 degrees Celsius), are not reasons to delay vaccinations. Your child will not experience any added side effects.

Also, anyone who has received immune globulin (a blood product) by injection should not receive the measles, mumps, or rubella vaccines for 3 months or more, depending on the dose of immune globulin. The antibodies in this blood product can interfere with the establishment of immunity after vaccination.

10. Who should not be vaccinated?

Anyone who has had a severe allergic reaction (anaphylaxis) after receiving a vaccine should not receive that vaccine again unless the exact cause of the reaction is determined. Anaphylaxis involves a person going into shock and having difficulty breathing. This type of reaction to a vaccine is extremely rare.

Anyone with a weakened immune system should not receive live virus vaccines such as the MMR or varicella vaccines. This includes people with congenital immune deficiency disorders, people who have had a bone marrow or organ transplant, people receiving chemotherapy for cancer, and people receiving high doses of steroids.