5 min Read

Understanding immunization

We asked Dr. Upton Allen,
Division Head of Infectious Diseases at Sick Kids Hospital, to go over some of
the finer points.

What is the number one reason parents give when they express resistance or refuse to get their child immunized?

The reasons vary, but one common concern is that they feel that their child’s immune system cannot cope with the foreign substances (antigens) vaccine. As well, many parents do not actually resist having their child immunized, it is often that they lead very busy lives and do not follow their child’s immunization schedule.

How can the medical community effectively address that concern/fear?

Education. It is important for parents who are hesitant to know that the numbers of these antigens are few compared with the numbers to which children are exposed to during activities of daily living. As such, they should not be fearful about the antigens in the vaccines as their children are often exposed to these of similar types of substances already. Coupled with education, there should be more information sharing about how vaccines are developed with reference to the safety testing and surveillance for adverse effects. 

Outbreaks continue to make headlines. What are the more worrisome diseases that kids could get if they’re not vaccinated?

Vaccine-preventable diseases include (but are not limited to) measles, whooping cough and tetanus. Childhood vaccines also provide protection against other vaccine-preventable infections that might result in serious diseases such as meningitis and some types of pneumonias and blood stream infections.

Here is some more information about some of these vaccine preventable diseases:

Measles: Measles is caused by a virus. It spreads very easily. Symptoms include: fever, cough, runny nose, red eyes, sleepiness, irritability (feeling cranky or in a bad mood) and small, white spots which may also show up inside the mouth and throat. Severe complications and even death can result from measles.

Mumps: Mumps is an infection caused by a virus. It passes easily from person to person, so prevention is very important. The main symptom of mumps is painful swelling in the cheeks and neck. Symptoms can also include: fever, headache or earache, tiredness, sore muscles, dry mouth, trouble talking, chewing or swallowing, or loss of appetite. Although most people fully recover from mumps within seven to 10 days, in rare cases the virus may cause complications. These include deafness, meningitis (infection of the covering of the brain and spinal cord) or infections of the testicles or ovaries.

Rubella: Rubella or German measles is a highly contagious disease caused by the rubella virus. It can be spread through direct contact, such as kissing an infected person, or through the air, such as when an infected person coughs or sneezes. In children, symptoms can include: a rash that starts on the face and spreads to the rest of the body, a low-grade fever, nausea, inflammation of the lining of the eye. Sometimes a rubella infection can cause complications. These are rare. The main complications results from the congenital rubella syndrome in infants born to mothers who contracted rubella in pregnancy. This syndrome may include serious eye, heart and neurologic problems.

Can you explain herd immunity?

Herd immunity is also referred to as community immunity and it enables protection for those who are particularly vulnerable to vaccine-preventable diseases, but who cannot be vaccinated. These individuals include young babies, elderly people and in some cases pregnant women and people with weakened immune systems. The way that herd immunity works is that if a high percentage of the population is vaccinated, it is difficult for infectious diseases that are also contagious to spread, because there are only a few people who can be infected. A good example relates to measles; if someone with measles is surrounded by people who have been vaccinated against measles, this stops the spread of the disease as it cannot easily be passed on to anyone. Without vaccination, we put our kids at risk of catching and spreading diseases. Herd immunity does not protect against all vaccine-preventable diseases. For example, tetanus is caught from bacteria in the environment, and not from person-to-person contact. Regardless of how many people around you are vaccinated against tetanus, herd immunity will not protect your child.

What should parents do if they have a friend or neighbour who doesn’t believe in immunizing?

It would be useful to help hesitant families get the information that they need to become more informed, rather than shaming parents who choose not to vaccinate. Resources from the websites of Ministry of Health, such as and Public Health Departments as well as physicians’ offices are useful for answering questions parents may have about vaccinating their child(ren). Families should also know that there are doctors available who will meet with them to discuss their concerns about vaccinating their children.

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