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The immune system II and Vaccination.


The immune system as we explored contains the innate system and therefore the adaptive system. The innate is that first line of defence against pathogens, they react within minutes to hours after infection. However, this method is non-specific. It means, it just attacks the pathogen without a decent plan: It uses the identical routine whenever a pathogen enters. The massive breakthrough is with the adaptive system. The adaptive system is found only in vertebrates: fishes, amphibians, birds, reptiles and mammals. The innate immune system acts sort of a paramedic who transports injured or sick people via an ambulance, stabilize the patient and sends him to the doctor(adaptive immune system). This implies that, when cells from the innate immunity are trying to beat the infection, a number of it travels to the adaptive system to present it with the case. The adaptive system accepts it and prepares to fight it if the innate system is unable to neutralise the pathogen. About 95% of the time, the innate system can annihilate pathogens.‌

‌The adaptive system can be described as a slow but sure method of the system. It always takes seven to ten days before a response is given. But when it does, it's specific: it eliminates the specific pathogen if it can. It does that by binding to the antigen(pathogen) then kills it directly or calls out for other cells to eliminate it. The great news about the adaptive system is that it's ready to identify plenty of antigens even antigens that are artificially manufactured within the laboratory. Also, because the adaptive system is sort of a terminator, it can differentiate between cells or proteins within the body from those that are foreign(pathogens). Diseases such as hypersensitivity, autoimmunity and cancers can occur if for some reasons the adaptive system loses this feature. Lastly, the adaptive system includes a memory. It implies that, after it encounters a pathogen, it keeps a number of its cells or antibodies that fought against the pathogens. Hence, upon another exposure, it can recall the previous contact with a foreign molecule and respond to it in a very learned manner, that is, with a more rapid and bigger response.‌

‌The adaptive system uses components like the B lymphocytes that produce antibodies and T lymphocytes that attack pathogens that affect cells. This implies that, when the adaptive system is activated, it can either produce antibodies or cells which will respond and eliminate pathogens depending on the nature of the pathogens. Antibodies are usually for extracellular pathogens whilst T cells are for intracellular pathogens or secrete molecules to aid the process.‌

‌The adaptive system can be natural or artificial. With both types, it will be either passive or active. For active, it means the body is vigorously engaged in producing an immune reaction whereas in passive, it implies that, the substance is given to an individual to elicit the response.‌

Below is a picture illustrating this process.

‌Active artificial type of adaptive immunity forms the basis for vaccination.‌


The understanding and principle of vaccination began 1000s of years ago.‌ Once upon a time in the 430BC during the Peloponnesian War, Thucydides, a great historian, in describing the plague in Athens wrote that, only individuals who had recovered from the plague could nurse the sick because they would not contract the disease a second time.

The principle behind vaccination generally is to introduce a weakened form, parts or the dead pathogen into your system. Because it has been weakened, it can cause no harm. The body then produces antibodies or manufacture cells that will eliminate it without causing harm to the body. This means that the body now has antibodies or cells that can destroy the pathogen without even meeting the live pathogen. Thus, if it should encounter the live pathogen, it already has gotten mechanisms(antibodies or cells) to fight it therefore preventing any surprises.‌

‌Edward Jenner demonstrated this principle within the 1790s. During that period, there was a plague of smallpox that affected humans. He observed that milkmaids who took care of cows had contracted a disease from cows called cowpox and were shielded from smallpox: A disease that affected humans and caused disfiguring disorders and death. He observed that the two diseases were closely related but one was more virulent(severe) than the other. He then inoculated an 8-year-old boy with pustules from cowpox. After some days, he subjected him to smallpox and he didn't become infected. He wrote a paper to disseminate his discovery but his paper was rejected. However, his method spread throughout Europe. Today, he is considered the father of vaccinology because he demonstrated immunity to smallpox.

100 years later, Louis Pasteur experimented on chickens using the bacterium that caused cholera. He hypothesized and proved that a weakened pathogen(cholera bacteria) will reduce the virulence of the pathogen and such attenuated strain may well be administered to guard against the disease. He called the attenuated strain(weakened form) a vaccine from the Latin word Vaccaea meaning cow, in honour of Edward Jenner's work with cowpox inoculation.‌

‌Now, the method of vaccination has been extensively researched and has been one of humanity's greatest achievements.

Questions people may ask regarding vaccines

  1. Are vaccines safe?

Vaccines are absolutely safe. They have gone through phases of clinical trials and have been approved.

2. Should I get a vaccine even though I have contracted a disease and recovered?

The answer is yes. Even though you have recovered, it is essential to get a vaccine if you are asked to. This boosts the antibodies in your body. People respond differently to diseases, hence, to be on the safer side, take the vaccine and avoid any surprises.

3. Why are there no vaccines for certain diseases such as HIV/AIDS?

There has been extensive research to produce vaccines for most diseases but the challenges are enormous. For example, with HIV, the genetic diversity is wide and it replicates faster, so it is difficult to provide a vaccine that destroys all its subgroups. Also, HIV targets the cells that will mount a response to defeat them. Thus, even if a vaccine is introduced, the cells that kill the virus have already been destroyed or reduced.

How to keep the system strong

1. Lifestyle: Balanced diets with a focus on fruits and vegetables. Exercise and enough sleep will boost our immune system.‌

2.Reduce stress: stress hormones inhibit the right functioning of the system. this could be reduced by sleep or rest. During sleep, the strain hormones cortisol are reduced and makes the immune cells active. One may notice that students often fall sick during the examination period. This may be because they stress themselves and reduce the function of the immune system. This makes opportunistic microbes take charge and cause diseases.‌


Handwashing is a basic process to stop the entry of microorganism into our body. This doesn't only do with the hands but our whole body.

The immune system is essential because it holds the key to good health. Good health leads to wealth and a good life. So live it well!!!


A young lady who is excited to influence the society and world with the knowledge she has acquired.