The first vaccine was created in 1796 by Dr. Edward Jenner for protection against smallpox, and research efforts have continued to explore various technologies for the development and delivery of vaccinations. The National Institute of Allergy and Infectious Diseases indicates that in recent years, scientific research has led to the development of various safe and effective vaccine types that elicit immune responses that protect against infections. Ongoing research efforts continue to explore novel vaccine strategies to avert both existing and emerging infectious diseases, and advances in understanding microbe-host interactions and improved laboratory techniques have paved the way for the development of vaccines.

There are various types of vaccines, and depending upon the disease or pathogen that is targeted, multiple technologies have been developed. In the United States, depending on the vaccine, there are four routes of administration, including the intranasal route (such as the live attenuated influenza vaccine [LAV], which is the only vaccine administered via this route), subcutaneous injection, intramuscular injection, and via the oral route. The rotavirus vaccine is the only routinely recommended vaccine that is administered orally.

While vaccines are not 100% effective in preventing disease, they can be instrumental in diminishing the risk of infections and the severity of diseases caused by the targeted pathogen.

The types of vaccine technology platforms include the following:

• LAVs are one of the earliest methods of vaccines, developed from a weakened (also referred to as attenuated) version of the disease-causing pathogen. LAVs use a weakened pathogen that cannot replicate, preventing symptoms. LAVs are primarily used for viruses. They stimulate memory B-cells for long-term immunity, mimicking a natural infection, and one or two doses typically provide lifelong protection without causing illness or being contagious. Since they contain a small amount of the weakened live virus, certain individuals should consult their healthcare provider before receiving them, including individuals with weakened immune systems, chronic health conditions, or those who have undergone an organ transplant.
• Inactivated vaccines are among the earliest vaccine types. They are designed from a killed version of the disease-causing pathogen and do not elicit as robust an immune response as LAVs. While they require periodic booster shots to maintain immunity, they often have fewer adverse effects than LAVs.
• While messenger RNA (mRNA) vaccines have been studied for decades, they are one of the newest platforms approved for vaccine delivery, marking the COVID-19 vaccine as the first FDA-approved mRNA vaccine in December 2020. mRNA vaccines make proteins to trigger an immune response and confer several benefits compared with other types of vaccines, including shorter manufacturing times and, because they do not contain a live virus, there is no risk of causing disease in the person who is vaccinated.
• Subunit, recombinant, polysaccharide, and conjugate vaccines utilize specific pieces of the germ—like its protein, sugar, or capsid—and do not contain any live pathogens. They are designed to produce robust and targeted protection against specific diseases. Subunit vaccines can be created in two ways: either directly from the original pathogen or through recombinant methods. Recombinant vaccines utilize another organism to generate the vaccine antigen.
• Toxoid vaccines utilize inactivated toxins produced by bacteria or viruses to build immunity against the specific parts of the pathogen that cause disease rather than the entire organism. The immune response is targeted at this particular toxin. These vaccines do not provide lifelong immunity and require periodic booster shots.
• Viral vector vaccines use a modified version of a different virus as a vector to deliver protection. They typically trigger a robust immune response. Only one dose of the vaccine is generally needed to develop immunity, and boosters may be required to maintain immunity.

An excellent resource on how vaccines are developed and approved for use can be found on the CDC’s website.

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.