How do vaccines actually work?

how do vaccines work

Whether travelling abroad or taking extra precautions to stay healthy this winter, chances are that you’re considering vaccination.

Learn more about how vaccines work and how it can shield against disease.

Vaccination is a miracle of modern medicine.  In the past two centuries, it has saved millions of lives. Every year, immunisations save an estimated 2 to 3 million lives. And, thanks to vaccines, we no longer have to fear smallpox or paralysis from polio.

Vaccines, says the World Health Organization (WHO), are biological preparations that improve our immunity to particular diseases. They help to prepare our bodies to fight disease faster and more effectively.

Produced from actual viruses or bacteria

These preparations are produced from small amounts of weak or dead germs (e.g. viruses or bacteria) that cause diseases such as measles, mumps, or the seasonal flu. Because vaccines aren’t made from live germs, they’re generally safe to use.

It’s also worth knowing that all vaccines used in South Africa’s Expanded Programme on Immunisation, are manufactured according to strict safety requirements.  All vaccines are checked by the Medicines Control Council (MCC) to ensure that they’re safe and effective.

Note, however, that some people cannot get certain vaccinations because of their age or health (e.g. children younger than 6 months shouldn’t get the flu vaccine).

How vaccines keep us healthy

Would you like to understand how vaccines keep you healthy? The US Centres for Disease Control and Prevention (CDC) explains the process as follows:

  • Your body’s immune system uses different types of white blood cells to fight infections.
  • When you encounter a germ for the first time, it can take a while for your body to build up its defenses (e.g. creating more white blood cells to attack and destroy the germs).
  • Once you’ve had an infection, your immune system remembers what it did to protect you against the disease. Your body keeps a few of the white blood cells (so-called “memory cells”) to help you react in an appropriate way when you encounter the germs again.
  • Vaccines help your body to go through the above process by imitating infection. However, because they’re made up of weak or dead germs, they’re highly unlikely to make you sick
  • Getting a vaccine helps your body to build up the “memory cells” that will help your immune system to fight off the disease when it encounters the same germs again.


By Carine Visagie

References: –
Facts about immunization. EPI (SA) Fact Sheet. South African Department of Health.

The Content on this site is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition

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