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COVID-19 vaccines

COVID-19 vaccine – mRNA (age 6 months and older)

Learn about the COVID-19 mRNA vaccine, doses, side effects, and safety.

COVID-19 mRNA vaccine

COVID-19 mRNA vaccines help protect you against getting very sick from COVID-19 and needing care in the hospital.

The Moderna Spikevax KP.2 and Pfizer-BioNTech Comirnaty KP.2 vaccines are available in Alberta. They are updated mRNA vaccines that help protect you against the COVID-19 strains that are currently spreading.

Who should get this vaccine

Everyone is at risk of COVID-19.

COVID-19 vaccines are free and recommended for everyone age 6 months and older.

Who should not get this vaccine

You may not be able to get an mRNA COVID-19 vaccine if:

You have an allergy to any part of the vaccine.
You had a severe (serious) or unusual side effect after this vaccine or one like it.
You are under age 6 months.

If you have allergies or have had a side effect from this vaccine, check with your healthcare provider before you get the vaccine.

Although you can get the vaccine if you have a mild illness such as a cold or fever, you should stay home until you are feeling better to prevent spreading your illness to others.

Check with your healthcare provider about when you can get an mRNA COVID-19 vaccine if:

You had COVID-19 in the past.
You have a history of multisystem inflammatory syndrome as a child (MIS-C) or an adult (MIS-A).

Be sure to talk to your healthcare provider before you get an mRNA COVID-19 vaccine if:

You have a weak immune system (because of a medicine you take or a health problem).
You have had a stem cell or organ transplant.
You are getting CAR T-cell therapy (a type of cancer treatment).
You have a history of myocarditis, pericarditis, or both within 6 weeks of getting a dose of COVID-19 vaccine.

Already had COVID-19

If you have already had COVID-19, it is not yet known how long your protection will last or how much protection you will have against variants. It is important to get a COVID-19 vaccine even if you have already had the virus.

The vaccine may give you better protection if you wait a while after having COVID-19 and then get a vaccine. How long to wait depends on your health history, the number of doses of COVID-19 vaccine you have had, and your risk of getting very sick from COVID-19.

If you have had COVID-19 in the past, check with your healthcare provider about when to get a COVID-19 vaccine.

Pregnancy and breastfeeding/
chestfeeding

While you are pregnant, you have a higher risk of getting very sick from COVID-19. Getting a COVID-19 vaccine lowers your risk of getting seriously ill from the virus.

You can get an mRNA COVID-19 vaccine if you are pregnant or breastfeeding/chestfeeding. There is more to learn about the Moderna KP.2 and Pfizer-BioNTech KP.2 vaccines while pregnant or breastfeeding/chestfeeding, but the information from the original mRNA vaccines found no concerns.

If you are pregnant or breastfeeding/chestfeeding and have questions about getting a COVID-19 vaccine, talk to your healthcare provider.

Vaccines

If you are age 6 months to 11 years, you can get the Moderna vaccine.

If you are age 12 years or older, you can get either the Moderna vaccine or the PfizerBioNTech vaccine.

Doses

6 months to 4 years with a healthy immune system

If you are age 6 months to 4 years, you need 2 doses of COVID-19 vaccine, 8 weeks apart. The Moderna KP.2 vaccine can start or complete your 2-dose series.

If you have already had 2 or more doses of a non-KP.2 COVID-19 vaccine, you can get 1 dose of the Moderna KP.2 vaccine at least 3 months after your last dose of COVID-19 vaccine.

5 years and older with a healthy immune system

If you are age 5 years or older, you need 1 dose of a KP.2 COVID-19 vaccine. If you have had another COVID-19 vaccine in the past, you need to wait at least 3 months before getting a KP.2 COVID-19 vaccine.

Weak immune system

If you have a weak immune system, the number of doses you need depends on your age and how many COVID-19 vaccines you have had in the past.

You may have a weak immune system if:

You have had or will have an organ or stem cell transplant.
You have had CAR T-cell therapy (a type of cancer treatment).
You have kidney disease and need dialysis.
You have human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS).
You take certain medicines that weaken your immune system.

If you have a weak immune system:

You need 3 doses of KP.2+ COVID-19 vaccine if you have never had any COVD-19 vaccine.
You need 1 dose of KP.2 vaccine at least 3 months after your last dose if you have already had 3 or more doses of a non-KP.2 vaccine.
You need 1 or 2 doses of KP.2 vaccine to total a 3-dose series if you have already had 1 or 2 doses of a non-KP.2 vaccine.

Studies show that extra doses may give better protection to adolescents and adults with a weak immune system. In babies and children with a weak immune system, extra doses may also give better protection, but research is still ongoing to learn more.

Research has shown mRNA vaccines provide the best protection for people with a weak immune system. If you have had a stem cell transplant or are getting CAR T-cell therapy, talk to your healthcare provider about when you can get a dose of KP.2 vaccine and how many doses you need.

Additional dose

You can get an additional dose of KP.2 vaccine at least 3 months from your previous KP.2 vaccine dose if:

You are age 65 years or older.
You are age 18 years or older and live in a continuing care home or supportive living facility.
You are age 6 months or older and have a weak immune system.
You are an Indigenous person age 6 months or older.

Off-label use

"Off-label use" means the vaccine is used differently than the way it was originally approved. Vaccine experts support the following off-label uses for KP.2 mRNA COVID-19 vaccines and have no safety concerns:

You are age 5 years or older and get a dose of Moderna KP.2 sooner than 6 months after your last dose.
You are age 5 years or older and get more than 1 dose of a KP.2 vaccine.
You are age 6 months to 4 years and get more than 2 doses of a KP.2 vaccine.
You are age 6 months to 4 years and have already had 2 or more doses of a non-KP.2 vaccine, and you get a dose of a KP.2 vaccine sooner than 6 months after your last dose.

Consent for immunization

A parent or guardian provides consent for a child under age 18 years to get a COVID-19 vaccine. If a parent or guardian cannot be at the appointment, they can use the consent form at COVID-19 consent for children under 18. In some cases, children under age 18 years may be able to give their own consent.

Alternate decision-makers (such as an agent, guardian, specific decision-maker, or co-decision-maker for another person) can use the consent form when they can't attend an immunization appointment with the person they represent. They must also provide documents that show they are the authorized decision-maker.

The person being immunized must bring the completed and signed consent form to their appointment.

How well it works

The best way to protect yourself from COVID-19 is to get immunized. How well COVID-19 vaccines work is different for each variant (also called strain) of the virus. As new COVID-19 variants are identified, vaccines are updated to offer better protection.

They help to lower your risk of getting very sick from COVID-19 and needing care in the hospital.

Safety

Vaccine safety is a top priority. Canada uses extremely safe vaccines. Learn more about vaccine safety in Canada, including how vaccines are monitored for continued safety, and ingredients in vaccines.

COVID-19 vaccines and other vaccines

You can get most other vaccines at the same time as, any time before, or any time after an mRNA COVID-19 vaccine, including routine vaccines and the influenza vaccine. However, certain vaccines have a waiting period. If you had another vaccine in the last 2 weeks, check with your healthcare provider about when you can get the mRNA COVID-19 vaccine.

Side effects

There can be side effects from mRNA COVID-19 vaccines, but they tend to be mild and go away in a few days. Side effects may include:

redness, swelling, a hard spot, or feeling sore where you had the needle
feeling tired or having a headache
a fever or chills
body aches or sore joints
feeling sick to your stomach (nausea), vomiting (throwing up), loose stool (diarrhea)
swollen lymph nodes
swelling or feeling sore in your armpit or groin
feeling dizzy
a reduced sense of touch or a feeling of numbness

Children age 5 years and younger may also get an earache, get upset easily, be sleepy, cry, or may not want to eat.

At least 1 out of 100 people who got this vaccine reported 1 or more of these side effects. In some cases, it is unknown if the vaccine caused these side effects.

Current information shows that there is a similar risk of side effects after each dose of an mRNA COVID-19 vaccine.

It is important to stay at the clinic for 15 minutes after your vaccine. Some people may have a rare but serious allergic reaction called anaphylaxis. If anaphylaxis happens, you will get medicine to treat the symptoms.

It is rare to have a serious side effect. Call Health Link at 811 to report any serious or unusual side effects.

How to manage side effects

To help with soreness and swelling, put a cool, wet cloth over the area where you had the needle.
There is medicine to help with a fever or pain. Check with your healthcare provider if you're not sure what medicine or dose to take. Follow the directions on the package.
Some people with health problems, such as a weak immune system, must call their healthcare provider if they get a fever. If you have been told to do this, call your healthcare provider even if you think the fever is from the vaccine.

There can be mild, short-term side effects after getting a vaccine. Find tips to manage these side effects at home.

Rare events

There have been very rare reports of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) after getting an mRNA vaccine. Most reported cases happened within 1 to 2 weeks after getting the vaccine and were mild and got better with treatment.

The inflammation can cause shortness of breath, chest pain, or a very fast or abnormal heart rate. Get medical help right away if you have any of these symptoms.

Research shows that the risk of these rare events after additional doses is expected to be lower than it was after the original primary series (the first 2 doses) for most people.

Research is still happening to learn more about the risk of these rare events after a getting updated versions of the mRNA COVID-19 vaccines.

It is not known if having a history of myocarditis, pericarditis, or both puts you at higher risk of having these rare events after a COVID-19 vaccine. Talk to your healthcare provider before you get a dose of COVID-19 vaccine if:

You had myocarditis, pericarditis, or both within 6 weeks of getting a COVID-19 vaccine.
You have a history of myocarditis, pericarditis, or both and you have questions about getting a COVID-19 vaccine.

Your risk of getting seriously ill from COVID-19 is much higher than your risk of having a rare event after these vaccines.

Current as of: April 28, 2025
Author: Communicable Disease Control, Alberta Health Services

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Our work takes place on historical and contemporary Indigenous lands, including the territories of Treaty 6, Treaty 7 & Treaty 8 and the homeland of the Métis Nation of Alberta and 8 Métis Settlements. We also acknowledge the many Indigenous communities that have been forged in urban centres across Alberta.

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