Feeling better? Before vaccinations, nearly every child on the planet got measles by the age of 15.

Human trials for the new coronavirus vaccine began last week in Oxford. If successful, it would be the fastest production of a vaccine in history. But how does vaccination actually work?

  • How were vaccines invented?

    In the 1700s, there was a global endemic killing more than 400,000 people per year. Smallpox was, then, the deadliest disease known to man. It had affected pharaohs, ravaged the Roman Empire and decimated native American populations.

    There was a folk tale that milkmaids could not get the disease, and an English doctor named Edward Jenner thought there might be truth to the story. He noticed that milkmaids got blisters on their hands while milking cows with cowpox, and wondered whether infecting someone with a mild version of the disease could protect them against the lethal one. In 1796, he tested his theory on several people, injecting cowpox into their bloodstreams before doing the same with smallpox. None of his patients became unwell with the deadly illness. Edward Jenner had succeeded. He named the process after the Latin for cow, “vacca”.

  • What was the science behind it?

    Nearly 1,000 years before Jenner, physicians in China had noticed that the few people who survived the disease became immune to it. Knowing this, they ground up old smallpox blisters into a powder and used nose pipes to insert it.

    All of them had the right idea. When fighting an illness, the immune system creates antibodies targeted at specific germs related to that illness. Vaccines work by training the immune system to create antibodies in the same way, but they use weakened or killed forms of germs developed in laboratories. The process is like going to a self-defence class: the body’s natural defence system builds the right cells to fight the disease without being exposed to the real thing.

  • How effective is vaccination?

    Vaccination has probably saved millions of lives. In 1853, all infants in the UK had to have the smallpox vaccine. Just over 100 years later, in 1980, the vaccine had been so effective that the World Health Organisation announced the complete global eradication of the disease.

    Today, vaccines are used around the world to immunise people against all sorts of diseases. Most Western countries have succeeded in eradicating measles, a potentially dangerous disease that once affected nearly every child on the planet.

  • Are there side effects?

    Ever since vaccination has been in widespread use, there have been groups of people who worry about its side effects. Anti-vaccination movements started in the 19th Century and still exist today. Some people fear vaccination can bring on the disease it is trying to prevent, and cause allergies and autism in children. These concerns have been proven unfounded.

    Vaccinations do cause side effects, but they are mostly weak. For example, somebody may experience mild symptoms after the flu jab, like a headache or muscle pain. Although the symptoms may overlap with those of the actual flu, this is because the body is reacting to a weakened version of the virus, and simply means that the immune system is working. Most people agree that the side effects are worth tolerating to avoid the more dangerous illness.

  • Is vaccination compulsory?

    Not in the UK, although – as in most countries – there is a schedule of vaccinations advised for young children.

    Nearly everyone can be vaccinated, but there are a few who cannot have certain vaccines because they have immune disorders or allergies. In populations where most people have been vaccinated, even those who do not have antibody protection are safe. This is known as ‘herd immunity’.

    Unfortunately, this technique has become less effective in recent years due to those who avoid vaccination due to fears of side effects. In 2019, there were several new cases of measles in the UK and, as a result, the government is now considering making vaccines compulsory once again.

  • What’s the future of vaccination?

    Eradicating smallpox remains one of the greatest public health achievements in history. Scientists are working constantly to achieve even more success by improving vaccines and creating new ones. New technology means that vaccines could be administered using nasal spray, inhalers, and patches instead of needles. There are plans to use vaccination to target non-infectious conditions, such as allergies, and the process could even be used to treat cancerous lumps.

You Decide

  1. Lots of doctors think that some vaccinations should be compulsory for infants. Do you agree?


  1. Some people avoid the measles jab because they worry about the side effects. Make a measles poster informing people about the positives of vaccination.

Word Watch

A disease or condition regularly found in a specific area.
A mild disease causing similar lesions to smallpox.
Immune system
A complex network of cells and proteins that defends the body against infection. The immune system keeps a record of every germ it has ever defeated, so it can recognise and destroy the microbe quickly if it enters the body again.
Proteins produced by the immune system to help stop intruders (germs, foreign bodies) from harming the body.
The complete destruction of something.
A lifelong, developmental disability that affects how a person communicates with and relates to other people, and how they experience the world around them.
Schedule of vaccinations
These include routine vaccines for measles, mumps, and rubella, which used to be common childhood illnesses.
Immune disorders
A condition where the immune system doesn’t work properly, meaning vaccines can be dangerous.

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