From Cowpox to COVID: The Fascinating Journey of Vaccines

When you roll up your sleeve for a vaccine before you go travelling, you probably do not stop to think about where this lifesaving idea came from. But the story of vaccines is one of curiosity and clever thinking. It also involved some brave experiments that changed the course of human history.

And what is the best part? It is not just about the science. It is about how observation and common sense led to these discoveries that have saved millions of lives.

A Quick Look Back in Time

Long before the word “vaccine” even existed, people were already trying countless ways to protect themselves from deadly diseases. Centuries ago in parts of Asia and Africa, healers used to practice something called variolation. This involved taking a small amount of material from a person with smallpox and introducing it to a healthy person. This was usually done through a scratch on the skin. The basic idea for this was to cause a milder infection that would protect them from getting the full-blown fatal version of the disease. Yes, it was risky. But for some lucky one, it worked quite well.

Fast forward to the late 1700s in England, where smallpox was still a major killer. Then comes Edward Jenner who was a country doctor with a keen eye for noticing patterns. He noticed something quite curious among milkmaids who had caught cowpox did not seem to get smallpox. Seeing this, Jenner carried out an experiment in 1796. He took material from a cowpox sore and introduced it into a young boy’s arm. Later, when the boy was exposed to smallpox, he did not get sick. This was the birth of the first true vaccine. The word “vaccine” itself comes from vacca, which is the Latin word for cow.

The Spread of the Vaccine Idea

Jenner’s discovery spread quickly, and over the next two centuries, scientists worked to create vaccines for more and more diseases. Louis Pasteur developed vaccines for rabies and anthrax in the 1800s. The 20th century saw the creation of vaccines for diphtheria, polio, measles, mumps, rubella, hepatitis, and more. Each one helped push back deadly diseases that had once been a normal part of life.

In 1980, smallpox became the first disease ever to be completely wiped out in humans. This was all thanks to the worldwide vaccination campaign. Today, polio is close to being eliminated as well. Many illnesses that used to fill hospital wards are now rare in countries with good vaccination coverage.

How Vaccines Work

Think of your immune system as an army that protects you from germs like viruses and bacteria. When a dangerous germ enters your body for the first time, your immune system scrambles to figure out how to fight it and this can take days. That is when you feel sick. Once your immune system has met that germ, it remembers how to destroy it. So if you are exposed again, the attack is much faster and stronger.

A vaccine is like a safe rehearsal for your immune system. Instead of using the full, dangerous germ, a vaccine uses a weakened, killed, or even just a tiny harmless piece of it. This is enough to train your body without making you sick. So, if and when the real germ shows up later, your immune system is already a step ahead and ready to wipe it out before it causes serious illness.

Types of Vaccines Today

Modern science has given us different kinds of vaccines:

• Live attenuated vaccines use a weakened form of the germ like the measles or yellow fever vaccines.

• Inactivated vaccines use a killed version of the germ like polio shots.

• Subunit or protein vaccines use only specific pieces of the germ like hepatitis B.

• mRNA vaccines give your body instructions to make a harmless piece of the germ so your immune system can learn to fight it like some COVID-19 vaccines.

  
  

The Takeaway For Travellers

When you’re travelling, you might visit places where certain diseases are more common. Yellow fever, typhoid, and hepatitis A can ruin a trip and even be life-threatening. That’s why travel health clinics recommend vaccines before you go. They do not just protect you, they help prevent you from bringing diseases back home or spreading them to others.