Ottawa – Several vaccines for COVID-19 are authorized and available for use in Canada. These include messenger ribonucleic acid (mRNA) vaccines (preferred) and a protein subunit vaccine. The XBB.1.5 vaccines are now the recommended products. Refer to Preparations authorized for use in Canada for more information.
Novel coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Anyone can be infected with SARS-CoV-2. However, some populations are at increased risk of exposure to the virus due to living or occupational settings and some populations are at increased risk of severe outcomes due to biological and/or social factors.
Some side effects are reported to be very common (defined as 10% or more) among recipients of all vaccines. However, they are mild or moderate and transient, resolving within a few days. These side effects may include: pain, redness and swelling at the injection site; axillary (or groin) swelling or tenderness; fatigue; headache; muscle pain; chills; joint pain; and fever.
Serious adverse events following immunization can occur very rarely. Refer to Safety and adverse events for more information.
All COVID-19 vaccines induce humoral immune responses, including binding and neutralizing antibody responses, and have been shown to produce cellular immune responses in adult populations. The immune responses may vary depending on the product used, number of doses, interval between the doses (longer intervals result in higher antibody titres), the strains against which the immune response is assessed and how immunologically similar the strain is to the vaccine strain, and the age and underlying medical conditions of the vaccine recipient (antibody titres may be lower in older adults and those who are immunocompromised due to disease or medication). Antibody titres decrease over time since vaccination, although memory responses that can be boosted with vaccination or infection persist.