Teddies Talks Biology - Issue 9

Emma Somers and Alexis Mpanga—LVI

A vaccine is a suspension of antigens that are intentionally put into the body to create artificial active immunity, with active immunity being immunity to a pathogen following an exposure to said pathogen. When the body is exposed to a pathogen, B lymphocyte cells (a type of white blood cell) create antibodies, which help to destroy or neutralise the pathogen. (Antibodies are proteins that are capable of binding to sites on the pathogen ’ s surface called antigens.) When B cells encounter a pathogen, they create memory cells in addition to antibodies. Memory cells are a type of B cell produced following the primary infection that can recognize the pathogen. Memory cells can survive for decades, waiting within the body until the pathogen invades again, and when the body is exposed to the pathogen for a second time, the immune response is faster and more robust. Noradrenaline is a type of neurotransmitter found in the same nervous system as the hormone adrenaline. This works together with adrenaline to create the ‘ fight or flight ’ response. Immunity does not happen immediately after disease exposure. It can take days or weeks after the first exposure for active immunity to develop, however, once it does, the protection can last an entire lifetime. Highly effective vaccines will usually last a lifetime. This is because memory cells can recognise the pathogen, if the live version ever enters the body, and quickly produce antibodies to combat it. Usually, the response is so fast that it may result in a little discomfort or no noticed change to the individual. Less effective vaccines will often need subsequent injections, or top - ups. When many people in an area or in a community are vaccinated, the pathogen will find it diffi- cult to circulate, as most of the people it encounters are immune. The more people are vac- cinated, the less likely other people, who are unable to be protected by vaccines, are at risk of being exposed to the harmful pathogens. Often, the types of people who cannot receive vac- cines have underlying health conditions, such as HIV or allergies to components of vaccines, and the vaccine would risk them harm. In this case they must rely on herd immunity to be pro- tected. Vaccines can cause side effects, just as any medication can. Most side effects from vaccination are mild, such as soreness, swelling, or redness at the injection site. Some vaccines are associ- ated with fever, rash, and achiness. Serious side effects are rare but may include seizure or life -

threatening allergic reaction. Often, long term side effects of vaccines are un- known. The Covid - 19 vaccine, for ex- ample, does not have much research and information into the long - term side effects of the vac- cine, as the virus has not been a cause for concern for very long and the vaccine is a recent product.

Teddies Talks Biology I Issue 9 I June 2021

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