Issue of January 6, 2019

71th Courier Anniversary Issue
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How vaccines work

When infectious organisms like bacteria or viruses invade the body, the immune system is stimulated. White blood cells that form part of the immune system and considered the soldiers of the body are activated. One group moves to the site of infection, while another type of white blood cells, the lymphocytes produce antibodies to fight the invading organisms. These antibodies then try to destroy the bacteria or viruses and help the person recover from the illness.

Antibodies that are naturally formed during infection with certain viruses or bacteria remain in the body to protect the person from a repeat infection with the particular organism. For example, a person who develops measles after he/she is exposed to a case of measles will develop antibodies that confer lifetime immunity. This person will thus be considered immune to the measles virus.

While lifetime immunity can develop after natural exposure to certain diseases, the disease process itself entails certain risks. There can be serious complications during the disease. These complications can lead to deformities (example: Polio), liver cirrhosis or liver cancer (hepatitis B), male infertility (chicken pox) or the complications can be fatal. Vaccines were invented to stimulate the immune system to form antibodies without exposing a person to risks of serious complications.

There are two types of vaccines – active and passive. Active vaccines are made of weakened forms of bacteria or viruses. Examples are rubeola or measles, mumps, rubella (German) measles, chickenpox (varicella). Active vaccines may also be weakened components (example: toxins) of bacteria like tetanus toxoid and diptheria vaccine. Active vaccines may also contain only parts of a virus like hepatitis B.

Passive vaccines are made of pre-formed antibodies and are prepared as immune serum globulin. The protection is immediate but is short-term.

Current or recent mild illness with or without low grade fever, current or recent antibiotic treatment, previous mild to moderate pain, redness, or swelling at the site of a previous vaccination or fever less than 40.5 degrees Celcius, or family history of allergies to vaccines are conditions that do not affect vaccination. The general reasons why one should avoid vaccination are the following: Serious allergic reactions to eggs or egg components because some vaccines (example: flu vaccine) are prepared using embryonic chicken eggs (recombinant hemagglutinin influenza vaccine is safer to use among persons with severe allergy to eggs). Another reason to avoid vaccination is severe allergy to neomycin or streptomycin, allergy to gelatin, and severe allergy to specific vaccines.

Live virus vaccines like measles, mumps, rubella, and varicella/chickenpox vaccines are generally not recommended to persons with markedly weakened immune system, history of recent blood transfusion or immune serum globulin therapy (vaccination should be delayed for at least one month), and women who are pregnant or expect to be pregnant in 28 days, because of the potential effects of the vaccine to the fetus.

The required doses of a vaccine should be completed. The lymphocytes of the body are like people – they tend to forget what they do not often see. These lymphocytes therefore have to be reminded of the organism against which antibodies should be formed. The initial doses may not be enough to provide immunity. Immunity conferred by some vaccines may also decline so that booster doses should be given.

There are reports that in 2017, there were spikes in the number of measles cases, and about 110,000 deaths worldwide were attributed to the disease. Gaps in immunization explain the rise in measles cases.

Medical questions or concerns may be emailed to or

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