Introduction to immunisation

  Immunisation allows the body to defend itself better against diseases caused by certain bacteria or viruses. Immunity can be produced by the body naturally (when people are exposed to bacteria or viruses) or can be provided by doctors through vaccination. People who are immunised against a disease, do not usually get it, or contract […]


Immunisation allows the body to defend itself better against diseases caused by certain bacteria or viruses. Immunity can be produced by the body naturally (when people are exposed to bacteria or viruses) or can be provided by doctors through vaccination. People who are immunised against a disease, do not usually get it, or contract a mild form of it. However, as no vaccine is 100% effective, some people who have been immunised can still get the disease.

In communities and countries where vaccines are widely used, many previously common and / or fatal diseases (such as polio, measles, and diphtheria) are now rare or under control. Only one disease, smallpox, has been eradicated completely by vaccination. The vaccines have been very effective in the prevention of serious diseases and in the improvement of health throughout the world. However, effective vaccines are still not available for many important infections, including Ebola virus infection, most sexually transmitted diseases (such as HIV, syphilis, gonorrhoea and chlamydia) and many tropical diseases. (like malaria).

Following the recommendations for vaccination is very important for the person’s own health and for the health of his family and the members of his community. Many diseases prevented by vaccines are still present in the United States and are still frequent in other parts of the world. These diseases spread rapidly among unvaccinated children, who, because of the current ease of travel, are exposed even though they live in areas where the disease is not frequent.

The vaccines available today are highly reliable and most people tolerate them well. It is very rare that they cause adverse effects.

Remember that the help of an expert is an excellent option to avoid health problems. Here at Parkwood Green Medical we will assist you and help you adopt proper health habits that will ensure you feel fine.

Types of Immunisation

There are two types of immunisation:

Active immunisation

In active immunisation, vaccines are used to stimulate the body’s natural defense mechanisms. Vaccines are preparations that contain one of the following factors:

  • Non-infectious fragments of bacteria or viruses
  • A toxoid: a substance produced by a bacterium, which is usually harmful (toxin), but which has been modified to render it harmless
  • A complete and live microorganism weakened (attenuated) so that it does not cause the disease

The body’s immune system responds to a vaccine by producing substances (such as antibodies and white blood cells or leukocytes) that recognise and attack specific bacteria or viruses contained in the vaccine. Later, when the person is exposed to said bacteria or virus, the organism automatically produces those antibodies and other substances to prevent or reduce the disease. The process of administering a vaccine is called vaccination, although in some cases the generic term immunisation is used.

Vaccines that contain live but weakened microorganisms are:

  • Bacillus Calmette-GuĂ©rin (BCG for tuberculosis)
  • Chickenpox
  • Cholera (certain vaccines that are administered orally)
  • Nasal flu vaccine
  • Measles-mumps-rubella
  • Poliomyelitis (oral vaccine only)
  • Rotavirus
  • Typhoid fever (oral vaccine only)
  • Herpes
  • Yellow fever

Did you know…?

Some vaccines contain a weakened but living form of the virus against which they protect.

Passive immunisation

In passive immunisation, antibodies are directly administered against a specific infectious organism. These antibodies are obtained from various sources:

  • The blood (serum) of animals (usually horses) that have been exposed to a certain organism or toxin and have developed immunity
  • Blood drawn from a large group of people; in which case it is called combined human immunoglobulin concentrate
  • People who have antibodies against a particular disease (ie, people who have been immunised or who recover from the disease), in this case being called hyperimmune globulins, because these people have higher levels of antibodies in the blood

Antibody producing cells (usually obtained from mice) cultured in the laboratory

Passive immunisation is used in people whose immune system does not respond adequately to the infection, or in people who get an infection before being vaccinated (for example, after suffering a bite from an animal affected by rabies).

Passive immunisation is also used to avoid the disease when exposure is likely and the person does not have time to complete a series of vaccinations. For example, a solution containing gamma globulin active against the varicella virus can be administered to a pregnant woman who has no immunity to the virus and who has been exposed to it. The varicella virus can cause damage to the fetus and serious complications (such as pneumonia) to the mother.

Passive immunisation only provides effective protection for a few days or weeks, until the body removes the injected antibodies.

Administration of vaccines

Vaccines and antibodies are usually given by injection into a muscle (intramuscularly) or under the skin (subcutaneously). Sometimes the antibodies are injected into a vein (intravenously). A certain type of flu shot is sprayed on the nose.

More than one vaccine may be administered at a time, either in a combination vaccine or by individual injections, applied in this case in different parts of the body.

Some vaccines are administered systematically: for example, tetanus toxoid is administered to adults, preferably every 10 years. Some vaccines are routinely administered in childhood.

Other vaccines are administered mainly to specific groups of people. For example, the yellow fever vaccine is given only to people traveling to certain parts of Africa or South America. There are also other vaccines that are given after a possible exposure to a specific cause; For example, the rabies vaccine should be applied to people bitten by a dog.

Vaccination restrictions and precautions

For many vaccines, the only reason not to get vaccinated is a severe, life-threatening allergic reaction (such as an anaphylactic reaction) to the vaccine or any of its components.

Some vaccines, including most flu vaccines, contain very small amounts of material from eggs. Many people are allergic to eggs, but only those who have suffered severe allergic reactions to eggs should avoid the flu shot. If the person has had less severe reactions to the eggs (such as a rash), they may be given the influenza vaccine containing inactivated viruses, but not the one containing active viruses.

Vaccines containing live viruses should not be used, or should be postponed for people with certain characteristics, such as people with weakened immune systems due to some disorder such as AIDS, or the use of drugs that suppress the immune system (immunosuppressants), such as corticosteroids and antineoplastic drugs.

Remember that here at Parkwood Green Medical you can receive any type of medical assistance from top qualified experts in the area.