What is immunisation ?
Immunization, also known as vaccination, is a process that helps protect individuals from infectious diseases. It involves administering a vaccine, which contains weakened or inactivated forms of specific pathogens (such as viruses or bacteria) or parts of them. These pathogens stimulate the immune system without causing the actual disease, allowing the body to develop a defense mechanism against them.
How vaccines are developed ?
Vaccine production involves a complex process that includes several stages. While the specifics can vary depending on the type of vaccine being developed, here is a general overview of how vaccines are made :-
1) Research and development :- Scientists identify the pathogen causing the disease and study its characteristics. They work on developing a vaccine candidate that can stimulate the immune system without causing the disease itself. This involves identifying suitable antigens (pathogen components that elicit an immune response) and determining the optimal vaccine formulation.
2) Preclinical testing :- In the preclinical stage, the vaccine candidate is tested in the laboratory and in animal models to assess its safety and effectiveness. These studies help researchers understand the immune response generated by the vaccine and identify any potential concerns or side effects.
3) Clinical trials :- If the vaccine candidate shows promising results in preclinical testing, it progresses to clinical trials, which involve testing in human volunteers. Clinical trials typically consist of three phases :-
a) Phase 1 :- A small group of healthy volunteers receives the vaccine to assess safety, dosage, and immune response.
b) Phase 2 :- A larger group of volunteers, usually several hundred, receives the vaccine to further evaluate safety, immunogenicity (ability to provoke an immune response), and potential side effects.
c) Phase 3 :- The vaccine is administered to thousands or tens of thousands of individuals to assess its efficacy in preventing the disease and monitor for any rare side effects. This phase provides crucial data on the vaccine's safety and effectiveness.
4) Regulatory review and approval :- After completing clinical trials, vaccine manufacturers submit extensive data to regulatory authorities, such as the Central drugs standard control organisation (CDSCO) and Drug controller general of India (DCGI). Regulatory agencies review the data and determine whether to grant approval for the vaccine's use.
5) Manufacturing :- Once a vaccine receives regulatory approval, large-scale manufacturing begins. This involves growing the pathogen (for inactivated or subunit vaccines) or producing the specific components of the pathogen (for subunit or conjugate vaccines). Vaccine manufacturers follow strict quality control measures to ensure safety, consistency, and purity of the vaccine.
6) Formulation and packaging :- The vaccine components are combined and formulated into the final product. Adjuvants, substances that enhance the immune response, may be added to some vaccines. The final vaccine is then packaged into vials, syringes, or other appropriate containers.
7) Distribution and administration :- The manufactured vaccines are distributed to healthcare providers, clinics, hospitals, or other vaccination centers. Trained healthcare professionals administer the vaccines to individuals following recommended schedules and guidelines.
Throughout the entire process, rigorous quality control measures and regulatory oversight are in place to ensure the safety, efficacy, and quality of vaccines. Vaccine production involves collaboration between scientists, manufacturers, regulatory agencies, and healthcare professionals to provide safe and effective vaccines to the public.
What are the types of vaccines ?
There are several types of immunization, each designed to provide protection against specific diseases. Here are some common types of immunization :-
1) Live-attenuated vaccines :- These vaccines contain weakened forms of the disease-causing pathogens. The weakened pathogens can still stimulate an immune response, but they do not cause the disease in healthy individuals. Examples include the measles, mumps, rubella (MMR) vaccine and the oral polio vaccine (OPV).
2) Inactivated vaccines :- These vaccines contain killed pathogens or parts of them. While they cannot cause the disease, they can still stimulate an immune response. Examples include the inactivated polio vaccine (IPV) and the hepatitis A vaccine.
3) Subunit, recombinant, and conjugate vaccines :- These vaccines contain specific parts or components of the pathogen, such as proteins or polysaccharides. They do not contain the whole pathogen. Examples include the hepatitis B vaccine, the human papillomavirus (HPV) vaccine, and the Haemophilus influenzae type b (Hib) vaccine.
4) Toxoid vaccines :- These vaccines target the toxins produced by certain bacteria. They contain inactivated toxins that stimulate the production of antibodies against the toxins. Examples include the diphtheria and tetanus vaccines.
5) mRNA vaccines :- These vaccines use messenger RNA (mRNA) to provide instructions to cells in the body to produce a harmless piece of the pathogen, triggering an immune response. The mRNA vaccines against COVID-19, such as the Pfizer-BioNTech and Moderna vaccines, are examples of this type.
What are the ways to introduce vaccines ?
Vaccines can be introduced into the body through various methods. The most common ways to administer vaccines include :-
1) Injection :- Vaccines are often administered through intramuscular (into the muscle) or subcutaneous (under the skin) injections. This method allows the vaccine to enter the bloodstream and stimulate the immune system.
2) Oral :- Some vaccines can be given orally, usually in the form of drops or tablets. Oral vaccines are swallowed and absorbed through the digestive system. Examples of oral vaccines include the oral polio vaccine (OPV) and the rotavirus vaccine.
3) Nasal :- Certain vaccines can be administered as nasal sprays. The vaccine is sprayed into the nostrils and is absorbed through the nasal mucosa. The nasal flu vaccine (FluMist) is an example of a nasal vaccine.
4) Intradermal :- In some cases, vaccines may be administered directly into the skin, using a shallow injection. This method is less common but is used for certain vaccines, such as the Bacillus Calmette-Guérin (BCG) vaccine for tuberculosis.
How vaccines works ?
Vaccines work by stimulating the immune system to recognize and defend against specific pathogens, such as viruses or bacteria. Here is a general overview of how vaccines work :-
1) Introduction of the vaccine :- When a vaccine is administered, it introduces harmless components of the pathogen into the body. This can include weakened or inactivated forms of the pathogen, specific proteins or polysaccharides from the pathogen, or genetic material (such as mRNA) that provides instructions for producing harmless pieces of the pathogen.
2) Recognizing the threat :- The immune system recognizes the components of the vaccine as foreign or non-self. Specialized cells of the immune system, such as antigen-presenting cells (APCs), capture and process these components.
3) Activation of immune response :- APCs present the vaccine components to other immune cells called lymphocytes, specifically T cells and B cells. This interaction activates the immune response.
a) T cell response :- T cells play a critical role in coordinating the immune response. Some T cells, known as helper T cells, help activate other immune cells and stimulate B cells to produce antibodies. Other T cells, called cytotoxic T cells, can directly destroy infected cells.
b) B cell response :- B cells are responsible for producing antibodies. When activated by helper T cells, B cells differentiate into plasma cells that produce and release large amounts of antibodies. Antibodies are proteins that can recognize and bind to specific pathogens, marking them for destruction by other components of the immune system.
4) Memory cells formation :- During the immune response, some T cells and B cells become long-lived memory cells. These memory cells "remember" the pathogen encountered in the vaccine, enabling a faster and more robust immune response upon future exposure to the actual pathogen. This memory response helps protect against future infections.
5) Protection against the disease :- If a vaccinated individual later encounters the actual pathogen, the immune system can mount a rapid and targeted response. The memory cells quickly recognize the pathogen and trigger a specific immune response, preventing or limiting the infection. This can result in either complete protection from the disease or milder symptoms.
Vaccines not only protect vaccinated individuals but also contribute to the concept of herd immunity. When a significant portion of the population is immunized, the spread of the disease is reduced, protecting vulnerable individuals who cannot receive vaccines due to medical reasons.
Benefits to administer vaccines
1) Disease prevention :- Vaccines are designed to prevent infectious diseases. They stimulate the immune system to recognize and fight specific pathogens, reducing the risk of infection. Vaccination can help prevent a wide range of diseases, including measles, polio, influenza, hepatitis, pneumococcal infections, and many others.
2) Protection against severe illness :- Vaccines not only prevent infections but can also reduce the severity of the disease if a vaccinated person does get infected. Vaccinated individuals are less likely to experience severe complications, hospitalization, or death from vaccine-preventable diseases.
3) Eradication and control of diseases :- Vaccination plays a vital role in eradicating and controlling diseases. Through widespread vaccination campaigns, diseases like smallpox have been successfully eradicated, and others like polio are close to elimination. Vaccination programs can help reduce the incidence of diseases and even eliminate them from specific regions or countries.
4) Herd immunity :- Vaccination contributes to herd immunity, also known as community immunity. When a significant portion of the population is immunized, the spread of the disease is reduced, protecting vulnerable individuals who cannot receive vaccines due to medical reasons (such as infants, elderly, or immunocompromised individuals). Herd immunity helps protect the entire community and prevent outbreaks.
5) Reduced healthcare burden :- By preventing diseases, vaccines help reduce the burden on healthcare systems. Vaccination decreases the number of hospitalizations, doctor visits, and medical expenses associated with vaccine-preventable diseases. This allows healthcare resources to be allocated more efficiently to other critical health needs.
6) Global public health impact :- Vaccination has a significant impact on global public health. Immunization campaigns have saved millions of lives worldwide and continue to be a crucial strategy for improving health outcomes, particularly in low-income countries where access to healthcare and treatment options may be limited.
7) Cost-effectiveness :- Vaccines are considered highly cost-effective or even cost-saving interventions. The economic benefits of vaccination are substantial, as they help prevent expensive medical treatments, reduce productivity losses from illness, and avert the societal and economic impact of outbreaks.
Side effects of vaccines
Vaccines, like any medical intervention, can cause side effects. However, it's important to note that the vast majority of vaccine side effects are generally mild and temporary. The benefits of vaccination in preventing serious diseases far outweigh the risks of side effects. Here are some common side effects associated with vaccines :-
1) Injection site reactions :- It is common to experience pain, redness, or swelling at the injection site after receiving an injection-based vaccine. These reactions are typically mild and resolve on their own within a few days.
2) Fever :- Vaccines can occasionally cause a low-grade fever as the body's immune system responds to the vaccine. Fever is a normal immune response and usually resolves without intervention.
3) Fatigue and muscle aches :- Some individuals may experience temporary fatigue or muscle aches after receiving certain vaccines. These symptoms are generally mild and transient.
4) Headache :- Headaches may occur as a mild side effect of some vaccines. They typically resolve on their own without specific treatment.
5) Gastrointestinal symptoms :- Vaccines, particularly oral vaccines, may cause temporary gastrointestinal symptoms such as nausea, vomiting, or diarrhea. These symptoms are usually mild and self-limiting.
Serious side effects from vaccines are extremely rare. The vaccine development and approval process involves rigorous testing and monitoring to ensure safety. Regulatory authorities closely monitor vaccine safety and investigate any reports of adverse events. It's important to report any significant or persistent side effects to healthcare professionals or the appropriate health authorities.
It's worth noting that the risks of side effects vary depending on the individual, the specific vaccine, and other factors. Healthcare professionals are well-informed about the potential side effects of vaccines and can provide guidance and address any concerns or questions individuals may have. The benefits of vaccination in preventing serious diseases and protecting public health far outweigh the risks of potential side effects.
Here I will give you a link of national immunisation schedule which is given by ministry of health and family welfare of India. Which is used as a standard of vaccination all around India.
0 Comments