Medicine
Vaccines: How They Protect Us
From Wikipedia Clone, the free encyclopedia
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. Since their invention, vaccines have saved hundreds of millions of lives and eradicated or controlled many deadly diseases.
History:
- 1796: Edward Jenner created the first vaccine using cowpox to protect against smallpox.
- 1885: Louis Pasteur developed vaccines for cholera and rabies.
- 1952: Jonas Salk developed the polio vaccine.
- 2020-21: mRNA vaccines for COVID-19 (Pfizer-BioNTech, Moderna) were developed in record time.
How Vaccines Work:
Vaccines introduce an antigen (weakened/killed pathogen, protein subunit, or mRNA) into the body. The immune system:
1. Recognizes the foreign antigen.
2. Produces antibodies specific to it.
3. Creates memory B-cells and T-cells.
When the person later encounters the real pathogen, the immune system responds rapidly, preventing serious illness.
Types of Vaccines:
- Live-attenuated (MMR, yellow fever)
- Inactivated (flu, polio IPV)
- Subunit/protein (hepatitis B, HPV)
- mRNA (COVID-19)
- Viral vector (Ebola, some COVID-19)
Herd Immunity:
When a sufficient portion of a population is vaccinated (typically 70–95% depending on the disease), the pathogen struggles to spread, protecting even unvaccinated individuals.
History:
- 1796: Edward Jenner created the first vaccine using cowpox to protect against smallpox.
- 1885: Louis Pasteur developed vaccines for cholera and rabies.
- 1952: Jonas Salk developed the polio vaccine.
- 2020-21: mRNA vaccines for COVID-19 (Pfizer-BioNTech, Moderna) were developed in record time.
How Vaccines Work:
Vaccines introduce an antigen (weakened/killed pathogen, protein subunit, or mRNA) into the body. The immune system:
1. Recognizes the foreign antigen.
2. Produces antibodies specific to it.
3. Creates memory B-cells and T-cells.
When the person later encounters the real pathogen, the immune system responds rapidly, preventing serious illness.
Types of Vaccines:
- Live-attenuated (MMR, yellow fever)
- Inactivated (flu, polio IPV)
- Subunit/protein (hepatitis B, HPV)
- mRNA (COVID-19)
- Viral vector (Ebola, some COVID-19)
Herd Immunity:
When a sufficient portion of a population is vaccinated (typically 70–95% depending on the disease), the pathogen struggles to spread, protecting even unvaccinated individuals.
References
1. WHO. (2023). How do vaccines work? who.int
2. Plotkin, S. (2014). History of Vaccination. PNAS.
3. Jenner, E. (1798). An Inquiry into the Causes and Effects of the Variolae Vaccinae.