Comirnaty Pfizer is a COVID-19 vaccine developed by Pfizer and BioNTech. It is an active immunization to prevent COVID-19 caused by SARS-CoV-2 in individuals 12 years of age and older. Comirnaty is based on BioNTechs proprietary mRNA technology. It contains a molecule called mRNA that has instructions for making the spike protein of the SARS-CoV-2 virus. The vaccine works by preparing the body to defend itself against COVID-19. Comirnaty is given as an injection into the muscle. It is the first COVID-19 vaccine to be granted full approval by the FDA. The vaccine is not a live virus vaccine and does not contain SARS-CoV-2, the virus that causes COVID-19. Comirnaty may not protect all people who receive the vaccine. The possible risks of Comirnaty include side effects such as pain and swelling at the injection site, fever, fatigue, headache, and muscle pain. People who have had severe allergic reactions to any ingredient of the vaccine should not receive Comirnaty.