Vaccine: A milestone in medical history

In the past days of our civilization, we human faces many deadly diseases. Lacking of proper treatment, medicine and scientific knowledge many people faced lifetime defectiveness or even premature death. So that for centuries, humans have looked for ways to protect each other against deadly diseases. Scientists from all over the world looked for permanent remedy from these deadly diseases. Day by day scientists made progress and came to a conclusion, named “Vaccine”.

A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. It typically contains an agent that resembles a disease-causing microorganism, which is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins.

HISTORY:

Early Practices: Variolation

Ø  1000s AD: The earliest known method of immunization, called variolation, was practiced in China and India. People were deliberately infected with small amounts of material from smallpox sores to induce a mild form of the disease, which usually resulted in immunity.

Ø  1700s: Variolation spread to Africa, the Ottoman Empire, and eventually Europe and the Americas. It was risky but offered some protection against smallpox.

Edward Jenner and the Birth of Vaccination (1796)

The modern concept of vaccination began with the work of Edward Jenner, an English physician. Jenner observed that milkmaids who had contracted cowpox, a less severe disease, did not catch smallpox. He hypothesized that exposure to cowpox could protect against smallpox. Jenner tested his theory by inoculating an eight-year-old boy, James Phipps, with material from cowpox sores. The boy developed a mild case of cowpox and, when later exposed to smallpox, did not develop the disease. Jenner called this process vaccination (from "vacca," the Latin word for cow).

Ø  Expansion and Development of Vaccine (19^th Century)Late 1800s: The concept of vaccination expanded. The work of scientists like Louis Pasteur further advanced the field. Pasteur developed vaccines for rabies and anthrax by attenuating (weakening) the pathogens that caused these diseases.

Ø  1885: Pasteur’s rabies vaccine was successfully used to treat a boy who had been bitten by a rabid dog, marking a significant achievement in vaccine development.

The 20th Century: The Golden Age of Vaccines

Ø  1900s: The 20th century saw a surge in vaccine development. Vaccines for diseases such as diphtheria, tetanus, pertussis (whooping cough), tuberculosis, and polio were developed and widely distributed.

Ø  1955: The development of the polio vaccine by Jonas Salk was a monumental achievement. Later, Albert Sabin developed an oral polio vaccine, which became widely used.

Ø  1960s: The introduction of the measles, mumps, and rubella (MMR) vaccine significantly reduced the incidence of these diseases.

Modern Vaccine Innovations (Late 20th Century to Present)

Ø  1980: The World Health Organization (WHO) declared smallpox eradicated worldwide, the first disease ever eradicated by vaccination.

Ø  2000s: New vaccines were developed using advanced biotechnology, including vaccines for hepatitis B, human papillomavirus (HPV), and rotavirus.

Ø  2020: The COVID-19 pandemic accelerated vaccine development at an unprecedented pace. The first vaccines against COVID-19, based on mRNA technology, were developed and authorized for emergency use within a year of the virus's emergence. Companies like Pfizer-BioNTech and Moderna led this innovation.

HOW ARE VACCINES MADE?

A vaccine is made by first generating the antigen that will induce a desired immune response. The antigen can take various forms, such as an inactivated virus or bacterium, an isolated subunit of the infectious agent, or a recombinant protein made from the agent. The antigen is then isolated and purified, and substances are added to it to enhance activity and ensure stable shelf life. The final vaccine is manufactured in large quantities and packaged for widespread distribution. 

TYPES OF VACCINE:

Vaccines can be categorized into several types based on their composition, how they are produced, and their method of stimulating an immune response. Here are the main types of vaccines:

Name of Vaccine	Introduction	Example
Inactivated Vaccine	These types of vaccines contain inactivated, but previously virulent, micro-organisms that have been destroyed with chemicals, heat, or radiation, with intact but empty bacterial cell envelopes.	Polio vaccine (IPV), hepatitis A, influenza (flu shot), rabies.
Attenuated Vaccine	These vaccines contain a weakened (attenuated) form of the live virus or bacterium that causes the disease.	Measles, mumps, rubella (MMR), oral polio vaccine (OPV), varicella (chickenpox), yellow fever.
Toxoid Vaccine	Toxoid vaccines are made from inactivated toxic compounds that cause illness rather than the micro-organism.	Tetanus, diphtheria.
Subunit Vaccine	A subunit vaccine is a type of vaccine that includes only specific components of a pathogen (such as a virus or bacterium) rather than the whole organism. These components are the antigens—the parts of the pathogen that the immune system recognizes and responds to.	Hepatitis B Vaccine, Human Papillomavirus (HPV) Vaccine
Conjugate Vaccine	Conjugate vaccines are somewhat similar to recombinant vaccines: they’re made using two different components. Conjugate vaccines, however, are made using pieces from the coats of bacteria. These coats are chemically linked to a carrier protein, and the combination is used as a vaccine. Conjugate vaccines are used to create a more powerful, combined immune response	Haemophilus influenzae type b (Hib)

ADVANTAGE OF VACCINE:

Vaccines have saved millions of lives in Europe and across the world. Widespread vaccination has helped to eliminate smallpox and polio from Europe and made previously common diseases become rare. 

By getting vaccinated, people are protected against serious illness, and sometimes death, from vaccine-preventable diseases. It also protects against spreading those diseases among family members, friends, colleagues, classmates and the wider community. 

Vaccination is considered one of the most cost-effective public health interventions, as it prevents the costs associated with treating and caring for people who become ill.

When people in a population are vaccinated against an infectious disease, it becomes much less likely to spread from person to person. This protects against outbreaks of disease and, when enough people become immune, can enable ‘community immunity’ or ‘herd immunity’. This helps to protect not only those vaccinated but also, indirectly, those who are more vulnerable to disease. Young children, the elderly, people with weak immune systems, cancer patients, and people who cannot be vaccinated for medical reasons are all at risk when diseases start spreading through communities, so getting vaccinated can help protect them as well

SIDE EFFECT OF VACCINE:

Most people don’t have any serious side effects from vaccines. The most common side effects- like soreness where the shot was given- are usually mild and go away quickly on their own. The most common side effects after vaccination are mild. They include:

· Pain, swelling, or redness where the shot was given

· Mild fever

· Chills

· Feeling tired

· Headache

·Muscle and joint aches

THE FUTURE OF VACCINES:

Ongoing research focuses on developing vaccines for diseases like HIV, malaria, and cancer. There is also interest in creating universal vaccines that can protect against multiple strains of viruses, such as a universal flu vaccine.

This article is taken from the Galen Gazette, August 2024, Issue No. 04.  The author, Sakib Hasan, is a fifth-semester pharmacy student at Comilla University.