Prior to administering COVID-19 vaccines, health care providers must, at a minimum, review:
Most COVID-19 vaccines approved for people 6 months of age and older begin with 2 doses. These initial doses are called a primary series. The immune response to the first dose of a COVID-19 vaccine is not as strong or sustained as 2 doses. The second dose is essential for developing better, longer-lasting protection.
If you're moderately to severely immunocompromised due to disease or treatment, you may have a lower immune response to COVID-19 vaccination.
For this population, the National Advisory Committee on Immunization (NACI) recommends the following:
A primary series of 3 doses of an mRNA vaccine should be offered to individuals considered moderately to severely immunocompromised. Those who received other vaccine types to begin their primary series should receive an additional dose of an mRNA vaccine. The doses in the primary series should be given 4 to 8 weeks apart. People moderately to severely immunocompromised are encouraged to speak with a health care provider to learn more about vaccination and other ways to protect themselves against COVID-19.
Additional doses of the COVID-19 vaccines received after completing the primary series are called booster doses. Booster doses are important because protection from a primary series decreases over time. Booster doses increase protection by activating your immune response to restore protection that may have decreased over time. They improve protection against severe outcomes and may also reduce the risk of post-COVID-19 condition. Whether it's a booster dose or a primary series, you may be offered a different COVID-19 vaccine than the one you received previously. It’s safe and effective to do so.