Final answer:
Hypersensitivity reactions are more likely to occur with live attenuated vaccines due to a more comprehensive immune response and the risk of the virus reverting to a disease-causing form. Subunit, toxoid, and conjugate vaccines have a lower risk of side effects due to containing only the essential antigens. Inactivated vaccines typically present a lower risk compared to live vaccines.
Step-by-step explanation:
Risk of Hypersensitivity in Different Vaccine Types
Hypersensitivity reactions, though rare, can occur with any type of vaccine. Live attenuated vaccines and inactivated vaccines contain the whole pathogen, either weakened or killed. However, live attenuated vaccines pose a higher risk of side effects, including hypersensitivity reactions. This is because by establishing an active infection, they stimulate a more comprehensive immune response, which sometimes leads to adverse reactions. Furthermore, there's the risk that these vaccines' viruses could revert to a disease-causing form through back mutations.
In contrast, subunit vaccines, which include toxoid and conjugate vaccines, often have a lower risk of side effects. Because they contain only the essential antigens, instead of the whole pathogen, the immune system's response is focused, reducing the likelihood of a hypersensitivity reaction. Conjugate vaccines enhance the efficacy of subunit vaccines against pathogens with protective capsules, specially formulated to work in children under two years old, who generally do not respond effectively to T-independent capsular polysaccharide antigens.
Inactivated vaccines present a lower risk of hypersensitivity compared to live vaccines as they do not produce an active infection. Instead, they solicit primarily a humoral immune response and often require multiple doses, which could lead to localized inflammation.