How this Vaccine Works
Pfizer-BioNTech and Moderna vaccines tell your body's cells to make "spike proteins." The spike proteins are specific to the virus that causes COVID-19. Your immune system will respond to the spike proteins by making antibodies that will fight off infection. Your new antibodies will break down the spike proteins and get rid of them. Your new antibodies will protect you from symptomatic illness if you are exposed to the COVID-19 virus. It is not known if the vaccine can prevent infection and transmission. The vaccine does not contain the virus and so it cannot give you COVID-19.
The Pfizer-BioNTech and Moderna vaccines have been tested in large clinical trials to ensure they have met safety standards, and has been licensed and approved by Health Canada.
Two doses of the Pfizer-BioNTech vaccine are required for full protection, given 21 days apart. Two doses of the Moderna vaccine are required between 18 and 28 days apart. It can be given to people 16 years of age and older, including seniors. After completing the two-doses, it may take another seven days to achieve maximum protection against COVID-19. At this time, there is no information on the long-term protection with this vaccine. In trials, the vaccines were around 95 per cent effective.
There is a small chance that you may still get COVID-19 after being vaccinated. It is important to continue with public health measures such as physical distancing, wearing a mask, and staying home if you are sick. Health care and other staff must still wear personal protective equipment (PPE) even after they have been vaccinated.
Side Effects and Risks
Some people may experience side effects from the vaccine, but they will likely be moderate and resolve after a few days. Some of the symptoms are part of the body's response to developing immunity.
Common side effects that have been reported in the clinical trials for this vaccine include:
- Pain at injection site
- Feeling tired
- Muscle or joint pain
- Fevers or chills
- Redness and swelling at injection site
- Serious allergic reactions such as anaphylaxis
In rare cases, serious allergic reactions (anaphylaxis) can occur. Allergic reactions can be treated and are usually temporary. Seek medical attention if you have trouble breathing, have hives or swelling of the face and throat. Vaccine side effects will continue to be monitored as people receive the vaccine. If you get a reaction to the vaccine, contact your health care provider who will report the side effect directly to public health. Public health will keep track of the reported side effects to make sure the vaccine continues to be safe.
- Delay getting vaccinated if you have a fever or are sick with COVID-19 symptoms.
- Avoid trying to get pregnant for at least two months after getting both doses of the vaccine.
- People with a bleeding disorders or who are on blood thinner medications should consult their health care provider before getting vaccinated.
Do not get this vaccine, if you:
- are under 16 years of age for the Pfizer-BioNTech vaccine and under 18 years old for the Moderna vaccine;
- are pregnant or breastfeeding;
- have an autoimmune disorder or a weakened immune system due to illness or treatment (unless you have consulted with your healthcare provider about the risk versus benefits); or
- have an allergy to an ingredient in the vaccine or had a previous severe reaction to this vaccine