5 Types of Vaccine Technology

Vaccines operate through various mechanisms of action, each engineered to stimulate the body's immune system for disease prophylaxis and operating via various approaches, ranging from introducing attenuated live pathogens to utilizing specific components of a germ or virus. Toxoid vaccines specifically target harmful bacterial toxins, while viral vector vaccines employ genetic codes as a delivery system and inactivated vaccines contain nonreplicating forms of pathogens. This article explores 5 diverse vaccine technologies, explaining both their limitations and advantages and providing examples of common vaccine types for each.

1. Live Attenuated Vaccines

These vaccines spur the body to create antibodies and memory immune cells when introduced to a pathogen. Initial “wild” viruses or bacteria are weakened, or attenuated, via repeat culturing, after which they are introduced to the human host to replicate and stimulate an immune response that resembles that from a natural infection.1 They are so like the natural infections they aim to prevent that lifetime immunity is often conferred after 1 or 2 doses.2 However, refrigeration is necessary, so access can be limited under this resource strain, and caution should be exercised for those who are immunocompromised, who have undergone an organ transplant, or with a confirmed pregnancy, as these vaccines still contain a live version of the bacteria or virus.2,3 Examples of common live attenuated vaccines are measles/mumps/rubella (MMR), shingles, and yellow fever.4

2. Polysaccharide/Subunit/Recombinant/Conjugate Vaccines

Unlike live attenuated vaccines that use entire strains of viruses or bacteria, these vaccines incorporate and introduce parts of a germ or virus,4 also known as subunits—including a protein, sugar, or capsid.2 The resulting immunity, initially introduced to its host via phagocytosis, is both targeted and significantly strong.5 According to the World Health Organization, these vaccines can safely build immunity without causing disease6; they are especially suitable in the setting of an immunocompromising disease owing to their stability, purity, and safety.7 Booster shots are often required for ongoing immunity.2 Examples of common subunit/recombinant/conjugate/polysaccharide vaccines are hepatitis B, pertussis (whooping cough), and pneumococcal.8

Examples of the vaccines included here are MMR, whooping cough, DTaP, Ebola, and rabies. | Image Credit: © daniiD-stock.adobe.com

3. Toxoid Vaccines

Toxoids are the products that result when the harmful substances, or toxins, produced by a bacteria or virus are first isolated and then weakened or inactivated prior to being inserted in a vaccine—similar to the components of subunit/recombinant/conjugate/polysaccharide vaccines.5,9 This is often accomplished through the use of formaldehyde in trace amounts. The goal of such a targeted approach is to prime the immune response through the production of neutralizing antibodies that recognize and target the toxic activity of the part of the virus or bacteria that causes a disease when it enters the body.2,8,10 Examples of common toxoid vaccines are diphtheria and tetanus, which are often combined with pertussis (altogether, DTaP), due to the cumulative protective effect against these life-threatening infections that are known to cause heart failure, breathing problems, and brain damage in babies and young children.10 Booster shots are recommended for ongoing immunity.

4. Viral Vector Vaccines

Unlike most conventional vaccines, viral vector vaccines do not contain antigens or immunogens. Instead, their mechanism of action is essentially as the safe delivery system for the genetic codes, or proteins, the immune system needs to fight, and they recruit the body’s own cells to accomplish that.8,11 This vaccine technology uses a modified version of a naturally occurring virus because of viruses’ known ability to get inside cells in an efficient manner and locate the nuclei to insert genetic material. The 2 principal types are nonreplicating vector vaccines that produce only the vaccine antigen and replicating vector vaccines that produce viral particles that subsequently infect other cells that then will produce antigens. Immunity can come after just 1 dose, and boosters may be needed. Cellular and humoral responses can result that can be stronger compared with inactivated or subunit vaccines.12 Examples of common viral vector vaccines are COVID-19 and Ebola.2,6,11

5. Inactivated Vaccines

Containing an inactive from of a pathogen treated with heat or chemicals to render it not harmful—meaning they are not live and cannot replicate—these vaccines are especially safe for individuals who are immunocompromised.1,8 They can spur immunity but are incapable of causing disease. Typically, immunity is not developed until a second or third dose, and even then, protection is primarily in the form of antibodies; however, with a response that is often weaker compared with live vaccines, several booster shots are needed for ongoing immunity, and adjuvants may be needed to enhance the immune response. This type of technology is used because it can produce a stable vaccine able to withstand transport and storage. Examples of common inactivated vaccines are flu, polio, and rabies.2

References

1. Wodi AP, Morelli V. Epidemiology and prevention of vaccine-preventable diseases. CDC. March 22, 2024. Accessed August 27, 2025. https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-1-principles-of-vaccination.html
2. Immunization: vaccine types. HHS. Updated December 22, 2022. Accessed August 27, 2025. https://www.hhs.gov/immunization/basics/types/index.html
3. Vaccines & immunizations: contraindications and precautions. CDC. July 25, 2024. Accessed August 27, 2025. https://www.cdc.gov/vaccines/hcp/imz-best-practices/contraindications-precautions.html
4. Shabir O. What is a live-attenuated vaccine? News Medical Life Sciences. Updated April 16, 2021. Accessed August 27, 2025. https://www.news-medical.net/health/What-is-a-Live-Attenuated-Vaccine.aspx
5. Ghattas M, Dwivedi G, Lavertu M, Alameh MG. Vaccine technologies and platforms for infectious diseases: current progress, challenges, and opportunities. Vaccines (Basel). 2021;9(12):1490. doi:10.3390/vaccines9121490
6. What’s in a vaccine? World Health Organization. June 4, 2025. Accessed August 27, 2025. https://www.who.int/news-room/feature-stories/detail/how-are-vaccines-developed
7. Hou Y, Chen M, Bian Y, Zheng X, Tong R, Sun X. Advanced subunit vaccine delivery technologies: from vaccine cascade obstacles to design strategies. Acta Pharm Sin B. 2023;13(8):3321-3338. doi:10.1016/j.apsb.2023.01.006
8. Understanding six types of vaccine technologies. Pfizer. Accessed August 27, 2025. https://www.pfizer.com/news/articles/understanding_six_types_of_vaccine_technologies
9. What kinds of vaccines exist, and how do they work to create immunity against disease? Immunize Colorado. April 28, 2022. Accessed August 28, 2025. https://www.immunizecolorado.org/what-kinds-of-vaccines-exist-and-how-do-they-work-to-create-immunity-against-disease/
10. DTaP (diphtheria, tetanus, pertussis) vaccine VIS. CDC. August 6, 2021. Accessed August 28, 2025. https://www.cdc.gov/vaccines/hcp/current-vis/dtap.html
11. What are viral vector-based vaccines and how could they be used against COVID-19? Gavi. December 29, 2020. Accessed August 29, 2025. https://www.gavi.org/vaccineswork/what-are-viral-vector-based-vaccines-and-how-could-they-be-used-against-covid-19
12. Tang J, Al Amin Md, Campian JL. Past, present, and future of viral vector vaccine platforms: a comprehensive review. Vaccines (Basel). 2025;13(5):524. doi:10.3390/vaccines13050524