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World Immunization Week 2017 – How do Vaccines Work?

Polio vaccine | Unicef Guinea
Polio vaccine | Unicef Guinea

The Desmond Tutu HIV Foundation (DHTF) has been researching HIV and providing outreach around Cape Town for over a decade. This includes research on the elusive HIV vaccine. This World Immunization Week 2017, we want to share some of the history of immunization, what research is ongoing right now and where vaccines will be in the future.

The first examples of vaccinations were documented in the 17th century: Edward Jenner noticed that milkmaids who had previously caught cowpox did not catch smallpox, which was plaguing the land. Cowpox provides immunity to smallpox so the milkmaids’ immune systems could fight it off. He created an immunity to the smallpox by scratching some cells from a cowpox scab into a patient’s skin. Today, scientists test vaccinations rigorously before releasing them for public use and cover a wide range of diseases. The researchers at the DTHF are involved in a number of vaccine studies, but how do vaccines work?

If the body detects a foreign bacterium or disease, then the immune system is there to fight it off. White blood cells create many different antibodies, each one tailored to fight a specific bacteria or virus. Antibodies lock onto to a part of the disease cell and neutralise it. The great thing about the immune system is that once the body has fought off an infection once, it remembers how to do it again. Even if it only sees the same infection five years later, it will still be able to fight it off quickly. However, the process requires you to get sick before your body can develop antibodies.

As incredible as the immune system is, sometimes it just isn’t good enough. For example, HIV damages part of the immune system’s cells so that the body can’t fight off HIV or other diseases effectively.

Fortunately, scientists have developed vaccines to skip the ‘getting sick’ part of an illness and give you all the perks of immunity. A vaccine is a substance you take to improve immunity to a disease. Typically, the vaccination will contain a part of weakened bacteria or virus as a ‘dummy’ target to help the immune system learn and practice for taking down the real thing. The patient doesn’t get a full blown infection, but the immune system responds as though the real disease were present. If a vaccinated person is ever infected by the real illness then the immune system can more easily recognise the threat and destroy it.

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There are diseases that used to be deadly, but today with vaccine the only negative impact we feel is the prick of a needle. Around thirty years ago, Polio (Poliomyelitis) used to paralyse 1,000 children a day.(1) Today the virus is nearly eradicated in Africa thanks to widespread and thorough oral vaccinations.(2) Mumps, which can cause infertility in serious cases, is now no more traumatic than two or three injections over a human lifetime. However, a vaccine for HIV still remains elusive.

Despite the availability of HIV prevention tools and treatment, over a million people still died from HIV in 2015.(3) A vaccination would be an effective method of fighting the virus. This is why DTHF is researching vaccines for HIV with many ongoing clinical studies. Thanks to antiretrovirals, HIV is now a manageable, chronic disease. A vaccine would be a celebratory turning point in eradicating HIV. In addition to the HIV vaccine, DTHF researches vaccinations for tuberculosis and human papilloma virus (HPV).

 

Written by Caroline Reid

References

  1. http://www.afro.who.int/en/polio.html
  2. http://www.who.int/mediacentre/news/releases/2016/nigeria-polio/en/
  3. http://www.who.int/features/qa/71/en/