Types of Vaccines

Live-Attenuated Vaccines

Modified “wild” type or disease-producing virus or bacterium that are weakened or attenuated in a laboratory, usually by repeated culturing. The “weakened” strain retains the ability to replicate (grow) and produce immunity which does not usually cause a disease.

Fragile – handling and storage must be considered
Fast – usually produces immunity to recipients with one dose

Examples: yellow fever, measles, rubella, mumps, chickenpox, and influenza

Inactivated Vaccines

Microorganism or virus is inactivated through heat, chemicals, radiation, or antibiotics. Although the pathogen’s ability to replicate is destroyed, the process of inactivation keeps the virus intact for the immune system to recognize it.

Multiple – shorter length in providing protection than live-attenuated vaccines and require multiple doses to create long-term immunity
Humoral – immunity generated by circulating antibodies as the first dose of vaccine “primes” the immune system

Examples: hepatitis A, poliovirus, rabies

Subunit, Recombinant, Polysaccharide, Conjugate Vaccines

Specific antigenic parts of the pathogen whether its protein (subunit), sugar (polysaccharide), gene segment (recombinant) or capsid are used to create the vaccine.

Subunit – isolated protein of interest from a pathogen to provoke a response from the immune system
Recombinant – gene code from a specific pathogen is inserted to another virus or into producer cells (commonly mammalian cell lines) in culture to produce the vaccine protein
Polysaccharide – an inactivated subunit vaccine composed of long chains of sugar molecules that are able to stimulate B cells without T-helper cell assistance
Conjugate – uses a part of a bacteria combined with a carrier protein to generate a strong immune response

Examples: hepatitis B, influenza, human papillomavirus, anthrax, acellular pertussis

Toxoid Vaccines

Toxin produced by a pathogen is used to make the vaccine. It creates immunity targeted to the toxin rather than the whole pathogen.

Toxoid – inactivated toxins

Examples: diphtheria, tetanus