Your child is starting treatment that will suppress the immune system. This may affect how your child’s body responds to routine immunizations that protect your child against disease.
This guide explains how different types of vaccines interact with immune-suppressing treatment. It also discusses special situations such as travel to other countries. You will need to work with your child’s regular health-care provider to make sure your child is up to date on all necessary immunizations and to help keep your child healthy while taking immune-suppressing treatment.
If you have any questions, speak to your child’s health-care team.
What causes a suppressed immune system?
The following treatments can all suppress the immune system:
- high doses of steroids for at least two weeks
- azathioprine
- 6-mercaptopurine (6-MP)
- methotrexate
- chemotherapy medications to treat cancer
- biologic agents and monoclonal antibodies
Malnutrition or the underlying condition that your child requires treatment for can also suppress the immune system.
Each treatment affects the immune system in a specific way. Recommendations about immunizations will depend on the treatment your child is receiving.
Types of vaccines
Inactivated vaccines
Inactivated vaccines do not contain any live viruses or bacteria that can cause disease. This means they are safe for patients whose immune system is suppressed.
The main concern with these vaccines is that a suppressed immune system may not respond to them, so they may not work as well. Therefore, the goal with inactivated vaccines is to make sure your child has had all of the necessary vaccines at least two weeks before starting immune-suppressing treatment.
Inactivated vaccines include:
- tetanus and diphtheria (Td) vaccine or tetanus, diphtheria and acellular pertussis (Tdap) vaccine
- inactivated polio virus (IPV) vaccine
- haemophilus influenzae type B (Hib) vaccine
- human papillomavirus (HPV) vaccine
- pneumococcal vaccine
- meningococcal vaccine
- hepatitis A and/or B vaccines
- influenza vaccine
- COVID vaccine
For hepatitis B vaccine, your child’s health-care provider may need to take a blood test to find out if your child has responded to the vaccine.
If your child is already taking immune suppression treatment and there are no plans to stop the treatment, they can receive inactivated vaccines according to the regular schedule. In some circumstances, changes to the routine schedule may be needed. A child may be considered at high risk of contracting certain vaccine-preventable illnesses (such as pneumococcal disease and influenza) when they are on immune-suppressing treatment and may receive vaccines according to the schedule for high-risk individuals.
Live vaccines
Live vaccines contain live viruses or bacteria that can cause disease. Patients whose immune system is suppressed should not take live vaccines.
Your child should have any necessary live vaccines four weeks before starting immune-suppressing treatment.
Live vaccines include:
- measles, mumps and rubella (MMR)
- live influenza vaccine given as a nasal spray (FluMist)
- rotavirus
Varicella (chicken pox) vaccine, while a live vaccine, is safe to give to children on low doses of immune-suppressing treatment.
Immunizing family members
If your child is taking immune-suppressing treatment, all family members who live in the same household should be fully vaccinated, including annual influenza and COVID vaccinations. This will help keep your child healthy.
However, some live vaccines work by causing a very mild form of the disease. For most people, this is completely safe, but people who have received these vaccines can pass germs to other people. This could make your child sick.
The following live vaccines are safe to give to family members:
- measles, mumps and rubella (MMR)
- yellow fever
- oral typhoid
The following live vaccines are safe with some restrictions:
- Chickenpox (varicella): About 5% of people who receive this vaccine develop a rash. If this happens, the child whose immune system is suppressed should avoid contact with this person. Contact your child’s health-care provider if this happens, as your child may need to take treatment to prevent infection.
- Rotavirus: It is possible that people who receive this vaccine may have live virus in their feces (stool). If your family members receive the rotavirus vaccine, wash hands thoroughly and often.
People who receive oral polio vaccine have live virus in their feces. Family members should not receive this vaccine. This vaccine is not used in Canada.
It is safe for family members to take all inactivated vaccines. These cannot be passed on to your child.
If your child has been exposed to an infectious disease
If your child has been exposed to an infectious disease, call your child’s health-care provider right away. Your child may need to have treatment to prevent infection.
Your child will need treatment after being exposed to any of the following diseases:
If your child is stopping immune suppressing treatment
The effects of immune-suppressing treatment last for a while, even after your child stops taking it. After stopping treatment, your child’s health-care provider should wait at least three months before giving any immunizations. This should give your child’s immune system time to recover and respond well to the immunizations.
Sometimes, a longer time period may be needed for certain immune-suppressing treatments.
There may also be some instances when your child's health-care provider may want to give an inactivated vaccine earlier (i.e., tetanus exposure), although there may be a chance your child’s immune system will not respond to it.
If your child will be travelling
If your child will be travelling, speak to your child’s health-care team at least six to eight weeks beforehand. Make sure all your child’s routine vaccinations are up to date, especially MMR, tetanus and pertussis (whooping cough).
Depending on where your child is travelling, other vaccines may be recommended as well.
The following inactivated vaccines are safe to give to a child whose immune system is suppressed:
- typhoid (injectable)
- Japanese encephalitis
- rabies
The following live vaccines are not safe to give to a child whose immune system is suppressed:
- yellow fever
- typhoid (oral)
- Bacillus Calmette-Guérin (BCG)
Your child’s health-care provider may also suggest consulting an infectious disease specialist or a travel medicine specialist.