B2-12 · A Shot in the Arm: The Story of Vaccines

A Shot in the Arm: The Story of Vaccines

In English, "a shot in the arm" means something that gives you new energy or hope. The phrase comes from vaccination – and for good reason. Vaccines are estimated to save several million lives every year. Yet few medical inventions have caused so much debate. To understand both sides, it helps to start at the beginning.

Milkmaids and smallpox

For centuries, smallpox was one of the deadliest diseases on Earth. It killed about three out of every ten people who caught it and left many survivors blind or badly scarred. In the 18th century, the English doctor Edward Jenner noticed something curious: milkmaids who had caught cowpox, a mild disease from cows, did not seem to get smallpox. In 1796, he tested his idea on an eight-year-old boy, James Phipps. He infected him with cowpox and later exposed him to smallpox. The boy did not get sick.

Jenner's experiment would never be allowed today, but it worked. The word "vaccine" comes from the Latin vacca, meaning cow. Almost two centuries later, after a worldwide vaccination campaign, smallpox became the first human disease ever to be completely eradicated. The last natural case was recorded in Somalia in 1977.

How vaccines work

Our immune system learns from experience. When a virus or bacterium attacks us for the first time, the body needs time to produce the right antibodies, and in the meantime we can become seriously ill. A vaccine gives the immune system a safe "preview" of the enemy – a weakened or killed germ, a part of it, or, in the newest vaccines, instructions for making a harmless piece of it. The body produces antibodies and memory cells. If the real disease arrives later, the immune system recognizes it and reacts quickly.

Vaccines also protect people who cannot be vaccinated themselves, such as newborn babies or people with weak immune systems. When enough people in a community are immune, a disease cannot spread easily. This is called herd immunity. For very infectious diseases like measles, about 95 percent of people need to be vaccinated for it to work.

Polio and the race for a vaccine

In the first half of the 20th century, polio terrified parents. Every summer, outbreaks paralyzed thousands of children, and some had to live in "iron lungs" – huge machines that helped them breathe. When the American scientist Jonas Salk announced a safe polio vaccine in 1955, church bells rang across the United States. Asked who owned the patent, Salk answered, "Well, the people, I would say. There is no patent. Could you patent the sun?" Thanks to vaccination, wild polio now survives in only a few areas of the world.

Fear and doubt

Paradoxically, the success of vaccines has created a new problem. Because most parents today have never seen a child with measles or polio, the diseases no longer seem dangerous – but the vaccines sometimes do. In 1998, a British doctor published a study claiming a link between the measles vaccine and autism. The study was later shown to be dishonest, the journal withdrew it, and the doctor lost his license. Dozens of large studies involving millions of children have found no such link. Still, the fear spread, and vaccination rates in some countries fell. As a result, measles outbreaks have returned to parts of Europe and the United States.

Like all medicines, vaccines can have side effects. Most are mild – a sore arm or a slight fever for a day or two. Serious reactions are very rare, and health authorities monitor them carefully. Doctors argue that the real question is not whether vaccines have any risks, but whether the risks are smaller than the risks of the diseases they prevent. For the vaccines in use today, the evidence clearly says yes.

The future

During the COVID-19 pandemic, scientists developed new mRNA vaccines in less than a year – much faster than ever before. The same technology is now being tested against other diseases, including some cancers. Two of the researchers behind it, Katalin Karikó and Drew Weissman, received the Nobel Prize in Medicine in 2023.

From a curious country doctor to a laboratory in the 21st century, the story of vaccines is a story of science, courage and trust. And trust, it seems, is the one ingredient that no laboratory can produce.