Vaccine Production Techniques
How Do Vaccines Work?
Before understanding how vaccines are made, we must understand what they do. A vaccine acts like a “mock drill” for our body’s immune system. It introduces a harmless version or a specific part of a disease-causing microbe (called a pathogen) into the body.
This harmless piece is called an antigen. The immune system recognises this antigen as a foreign invader and produces special protective proteins called antibodies to destroy it. Crucially, the immune system “remembers” this enemy. If the real, dangerous pathogen ever attacks the body in the future, the immune system is already trained and ready to fight it off instantly.
Historically, making vaccines took decades. Today, thanks to biotechnology, scientists have developed various advanced vaccine production techniques. These can be broadly divided into traditional methods and modern genetic methods.
1. Traditional Vaccine Techniques
These methods involve using the actual disease-causing virus or bacteria, but altering it so it cannot cause the actual disease.
- Inactivated Vaccines: In this method, the disease-carrying virus or bacteria is completely killed (inactivated) using chemicals, heat, or radiation. Because the pathogen is dead, it cannot multiply or cause disease, making these vaccines very safe. However, the immune response is sometimes weaker, so patients may need multiple “booster” doses over time.
- Real-Life Example: Covaxin (India’s indigenous COVID-19 vaccine), the Rabies vaccine, and the injectable Polio vaccine.
- Live Attenuated Vaccines: “Attenuated” means weakened. In this technique, scientists modify the live pathogen in the laboratory so that it becomes extremely weak. When injected, it multiplies very slowly—just enough to trigger a strong, long-lasting immune response, but not enough to make a healthy person sick.
- Real-Life Example: The BCG vaccine (used for Tuberculosis in India), Measles, Mumps, and Rubella (MMR) vaccines.
2. Modern and Recombinant Vaccine Techniques
Modern biotechnology allows scientists to create vaccines without using the whole pathogen. Instead, they use genetic engineering to isolate specific parts or genetic codes of the virus.
- Protein Subunit Vaccines: Instead of injecting the whole pathogen, scientists isolate just the specific protein (like the “spike protein” on the surface of a virus) that triggers the immune system. Because it only contains a tiny fragment of the microbe, the chance of side effects is extremely low.
- Real-Life Example: The Hepatitis B vaccine and Corbevax (a COVID-19 vaccine developed in India).
- Viral Vector Vaccines: This is an ingenious technique where scientists use a different, completely harmless virus as a “delivery van.” This harmless virus is called a vector. Scientists take the genetic code of the dangerous disease (like the COVID-19 spike protein) and paste it inside the harmless vector virus. When injected, the vector safely delivers the code into our cells, training our immune system without causing the actual disease.
- Real-Life Example: Covishield (the Oxford-AstraZeneca COVID-19 vaccine widely used in India) uses a harmless chimpanzee adenovirus as its vector.
- mRNA Vaccines (Messenger RNA): This is the most advanced and rapid vaccine technology available today. Unlike other vaccines, mRNA vaccines do not contain any viral parts or vectors. Instead, scientists create a synthetic piece of genetic code called messenger RNA (mRNA) in the laboratory. When injected, this mRNA acts as an instruction manual. It tells our own muscle cells to temporarily build the viral antigen (like the spike protein). Once the protein is built, the immune system reacts and learns to protect the body. After delivering the instructions, the mRNA naturally breaks down and disappears from the body.
- Real-Life Example: The Pfizer and Moderna COVID-19 vaccines.
3. Modern Manufacturing Concepts
For global health emergencies like a pandemic, discovering a vaccine is not enough; we must be able to manufacture billions of doses quickly.
- Vaccine Production Platforms: A “platform” is like the standard chassis of a car. Once a car company builds a good chassis, they can easily build different models (sedan, SUV) on top of it. Similarly, a vaccine platform is a standardized underlying technology (like the mRNA or Viral Vector method). When a new disease emerges (like “Disease X”), scientists do not have to invent a whole new vaccine from scratch; they simply change the specific genetic “cargo” on their proven platform. This drastically reduces the time needed to develop new vaccines.
- Adaptive Manufacturing: Traditional vaccine factories were built to produce only one specific type of vaccine. Adaptive manufacturing refers to modern, highly flexible factory designs. These facilities use modular equipment and disposable bio-bags (instead of massive steel tanks). This allows a single factory to “adapt” and quickly switch from producing a Polio vaccine to producing a COVID-19 vaccine in a matter of weeks, ensuring a rapid response to health crises.
