Final answer:
Subunit vaccines are considered safer because they are acellular and contain only the essential antigens, not full pathogens, thereby eliminating the risk of causing the disease they are intended to prevent.
Step-by-step explanation:
Subunit vaccines are safer than traditional vaccines because A) they are acellular and do not pose a risk for causing the disease. These vaccines contain only the essential antigens of a pathogen without whole cells or viruses, which minimizes the risk of side effects. Subunit vaccines can be produced via chemical degradation of a pathogen to isolate key antigens or through genetic engineering methods. Unlike live attenuated or inactivated vaccines that contain whole pathogens, subunit vaccines expose the patient to only critical antigens required for immunity.
Modern vaccine technology utilizes the structural knowledge of genomes and antigens for disease-causing organisms, thereby facilitating the design of safe and efficient subunit vaccines. For instance, the hepatitis B subunit vaccine is created by inserting a gene for a hepatitis B surface protein into yeast, with the resultant protein serving as the antigen without any viral genome present. Thus, subunit vaccines provide immunity without the associated risks of introducing an entire pathogen into the patient's body.