There are several types of COVID-19 vaccines, each employing different mechanisms to induce immunity. The main types include: - mRNA vaccines (e.g., Pfizer-BioNTech, Moderna) which use messenger RNA to instruct cells to produce the spike protein of the virus. - Viral vector vaccines (e.g., AstraZeneca, Johnson & Johnson) which use a harmless virus to deliver genetic material from SARS-CoV-2. - Protein subunit vaccines (e.g., Novavax) that include harmless pieces of the virus (often the spike protein) to trigger an immune response. - Inactivated or attenuated vaccines (e.g., Sinopharm, Sinovac) which use a killed or weakened form of the virus.
