Live attenuated vaccines
Contain a weakened form of a living pathogen that can replicate to a limited extent. They often produce strong, long-lasting immunity.
Examples: MMR, varicella, rotavirus, yellow fever, BCG, and intranasal live influenza vaccine. They are generally avoided in people with severe immunocompromise and during pregnancy. CDC guidance

Inactivated (killed) vaccines
Contain pathogens that have been killed, so they cannot replicate or cause infection. Booster doses are often needed.
Examples: inactivated polio vaccine, hepatitis A vaccine, rabies vaccine, and many injectable influenza vaccines.

Toxoid vaccines
Contain an inactivated bacterial toxin rather than the organism itself.
Examples: tetanus and diphtheria vaccines.

Subunit vaccines
Contain selected antigenic parts of a pathogen, rather than the whole organism.
Examples: hepatitis B vaccine, acellular pertussis vaccine, HPV vaccine, and recombinant influenza vaccine.

Polysaccharide vaccines
Contain purified capsular polysaccharides from bacteria. They may generate a weaker immune response in young children.
Example: pneumococcal polysaccharide vaccine (PPSV23).

Conjugate vaccines
Bacterial polysaccharide is linked to a protein carrier, producing better immune memory, especially in infants and young children.
Examples: Hib vaccine, pneumococcal conjugate vaccines, and meningococcal conjugate vaccines.

mRNA vaccines
Deliver messenger RNA that instructs cells to make a harmless antigen, which triggers immune recognition. The mRNA does not enter or alter DNA.
Examples: Pfizer-BioNTech and Moderna COVID-19 vaccines. CDC explanation

Viral-vector vaccines
Use a modified, harmless virus to deliver genetic instructions for an antigen.
Examples: some Ebola and COVID-19 vaccines.

Virus-like particle vaccines
Contain noninfectious structures that mimic the outer shell of a virus but have no viral genetic material.
Example: HPV vaccine.

Nucleic-acid and newer platform vaccines
These include DNA vaccines and some vector or nanoparticle-based platforms. Many are used in limited settings or are still being developed.