World Immunization Week is commemorated every year in the last week of April, i.e., from 24 – 30th, chiefly targets to promote the necessity of immunization and the use of vaccines to protect people of all ages against diseases and infections. A healthy nation begins with a healthy individual. Right from birth, a child is protected from various life-threatening diseases through vaccination. Although immunization is recognized as one of the world’s most successful health interventions and is quintessential in saving millions of lives every year, yet nearly 22 million children in the world today are not getting the vaccines they need, and many miss out on vital vaccines during the growing years.
Also Read: World Immunization Week: Why Vaccines Matter In These Days And Times of A Pandemic
This year the theme for World Immunization Week 2021 is ‘Long Life For All’, that chiefly helps in pursuit of a long life to be lived happily and healthily.
According to WHO, Immunization or Vaccination is the process through which an individual’s immune system is fortified against foreign microbial by inducing the same germ that causes the disease. This microbial is either killed or weakened to the point that it does not make one extremely sick but stimulates the immune system to produce antibodies, exactly like it would when an active and strong form of the disease attacks the body.
Also Read: Vaccines: Learn How They Work And What Common Side Effects They Cause
Read on to know more about the different types of vaccines that are used to immunize people against various infections right from birth.
The Different Types Of Vaccines
Based on how the immune system responds to the foreign microbe, who requires to be vaccinated and the best approach to design the vaccine, there are chiefly 6 main types of vaccines. These include:
Live-Attenuated Vaccines
These vaccines generally inject a weakened, live version of the germ or virus that causes a disease in the body. The germs are allowed to reproduce enough for the body to make memory B-cells, which can recognize and remember a virus and generate an immune response against it for many years after their initial immune response. Live-attenuated vaccines are quite similar to the original infection and provide a long-lasting immunity in just 1 or 2 doses.
This vaccine is useful against:
- Smallpox
- Chickenpox
- Measles, mumps, and rubella (MMR combined vaccine)
- Rotavirus
- Yellow fever
Inactivated Vaccines
These vaccines generally use a strain of a bacteria or virus that has been killed with heat or chemicals. These vaccines usually do not provide immunity that’s as strong as live vaccines or even lifelong immunity, hence it is important to take these vaccines in several doses (i.e., booster shots) over time. Even our indigenous vaccine Covaxin (BBV152) against coronavirus, uses adjuvant Alhydroxiquim-II to boost immune response and long-lasting immunity. Inactivated vaccines usually provide protection against:
- Hepatitis A
- Polio
- Rabies
- Flu
- Covid-19
Subunit, Recombinant, Polysaccharide, And Conjugate Vaccines
These vaccines mainly use specific parts of the germ or virus—like its protein, sugar, or capsid (a casing around the germ) to generate a very strong immune response that targets key pieces of the germ. These vaccines are highly significant as they can be given to most people including people with a compromised or weakened immune system or those with long-term health problems. One of the major drawbacks of getting these vaccines are that they are similar to Inactivated Vaccines and require booster shots to get long-term protection against the particular disease.
They are commonly used against:
- Human papillomavirus (HPV)
- Whooping cough
- Hib (Hemophilus influenza type b)
- Hepatitis B
- Shingles
- Pneumococcal disease
- Meningococcal disease
Toxoid Vaccines
Toxoid vaccines chiefly work by using toxins created by the bacteria or the virus to create immunity to the specific parts of the microbe that cause a specific disease, and not the entire bacteria or virus itself. Toxoid vaccines too may not offer life-long protection and needs to be taken in booster shots to get ongoing protection against the disease.
It is mainly used for:
- Diphtheria
- Tetanus
Viral Vector Vaccines
Viral vector vaccines primarily work by modifying another virus and use it as a vector to deliver protection against the intended virus. Some of the viruses used as vectors include adenovirus, influenza, vesicular stomatitis virus (VSV), and measles virus.
Recent uses of viral vector technology have been in Ebola virus and SARS-CoV2, and further studies have focused on viral vector vaccines against other infectious diseases like Zika, flu, and HIV as well.
Messenger RNA (mRNA) Vaccines
One of the most significant type of vaccines that have been studied and researched for several years, mRNA vaccines make proteins in order to trigger an immune response. Since they do not contain live or any weakened germ, the incidence of having the infection is bare minimum. Additionally, it also takes much lesser time to manufacture unlike other vaccines. MRNA vaccines are mainly designed in the current times to protect against the deadly and infectious SARS-CoV2 virus.
DNA And Recombinant Vector Vaccines
DNA and recombinant vector vaccines are two new types of vaccines that are currently under development.
DNA vaccines are designed to introduce a DNA that creates specific antigens from a germ. This DNA from the microbe once injected is reproduced by the body and is recognized by the immune system which then provides ongoing protection against further infection.
Also known as platform-based vaccines, recombinant vector vaccines are designed to trigger a natural infection and are quite significant at training the immune system to recognize and attack germs later in life. They mainly work by reproducing a live virus that has been engineered to carry extra genes from the germ infecting the body.
