BRAINCAKEVaccination
A vaccine contains antigens from a pathogen, given so that the body makes an immune response and memory cells without the person having the disease. This gives artificial active immunity.
The antigens in a vaccine can be:
• live attenuated (weakened) viruses, e.g. the MMR vaccine
• inactivated (killed) viruses, e.g. the injected polio vaccine
• subunits: purified viral proteins, e.g. the HPV and hepatitis B vaccines
• mRNA coding for a viral protein, which the body's own cells then make, e.g. some COVID-19 vaccines
After vaccination, the antigen is taken up by antigen-presenting cells. Specific T helper cells and B cells are activated, and B cells divide to form plasma cells, which make antibodies, and memory cells. This is the primary immune response.
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Key terms in this lesson
- memory cell
- A long-lived lymphocyte, produced after exposure to an antigen, that allows a faster, stronger secondary immune response on re-exposure.
More in Prokaryotic Cells
- Viruses and Disease
- The Spread of Viral Diseases
- Treating Viral Diseases
- Preventing Viral Diseases
- Disease Control
- Drug Development
- Pandemics
- Ethics
All 31 lessons in Prokaryotic Cells · All Edexcel AS-level Biology topics