Final answer:
Antibodies produced by a vaccine are specific to the antigens of the pathogen targeted by that vaccine and thus do not offer protection against different pathogens with differing antigens. This specificity necessitates different vaccines for different diseases. Viral mutations, like those seen in HIV and influenza, can further challenge the effectiveness of vaccines.
Step-by-step explanation:
Antibodies produced by a person receiving a vaccine against one infectious agent, like hepatitis A virus, do not protect them from a different infectious agent, such as measles virus, because these antibodies are highly specific. They are created in response to specific antigens or proteins present in the infectious agent that the vaccine is designed to target. When the immune system encounters these antigens, it produces antibodies that precisely match the antigens like a key that fits a lock. Since different pathogens have different antigens on their surfaces, the antibodies for one pathogen will not recognize or bind to the antigens of another, rendering them ineffective against different diseases.
For instance, the Hepatitis B vaccine elicits an immune response against the Hepatitis B virus's unique surface antigens, conferring protection against that specific virus. This is why each disease typically requires its own vaccine. Moreover, the effectiveness of vaccines can also be affected by the rate at which a virus mutates. For example, HIV rapidly changes its surface antigens through mutations, which decreases the ability of antibodies to recognize various strains of the virus - a challenge also inherent to influenza viruses.
Ultimately, the specificity of the immune response generated by a vaccine is both a strength, as it allows for targeted immunity, and a limitation, as it requires different vaccines for different diseases. Vaccines must be designed to induce an immune response against the very specific antigens of each different pathogen to be effective.