Vaccination
“You’ll just feel a little jab.” Ouch! That
wasn’t too bad, and it could save your life. Most of us have had “shots” from a
needle. These are usually vaccinations, and they are extremely valuable. They
help protect us against diseases.
VIRUSES
Most vaccinations are given to protect against diseases
caused by viruses. Viruses are germs, and they are extremely tiny. They infect
(get into) your body, multiply, and make you feel sick. Chicken pox is one
example of a disease caused by a virus. The chicken pox virus gets inside the
body and multiplies. It causes a fever followed by a rash of itchy red spots.
WHAT ARE VACCINES?
A vaccine is usually a small amount of liquid
that contains dead or weakened versions of a virus or other type of germ.
Weakened viruses can still multiply within the body but cannot cause disease.
Vaccines can also contain tiny amounts of harmful substances, called toxins,
which are made by the viruses. But they don’t have enough toxin to make you
sick.
Some vaccines are oral, which means you can eat
them or drink them. However, the powerful digestive juices in your stomach
would destroy most vaccines. So vaccines are usually given by needle.
BECOMING IMMUNE
Your body attacks and destroys the weakened virus
or toxin in the vaccine before it can make you sick. In this way, you become
immune to (protected from) the disease the virus causes. The vaccine enables
the body’s defenses, or immune system, to recognize and destroy the virus.
To destroy the virus, your immune system produces
special substances, called antibodies, in the blood. Antibodies are able to
fight and destroy particular viruses. If the real virus later invades, the
immune system can kill it very quickly, before it starts to multiply.
WHICH DISEASES?
Vaccination is carried out in many countries as a
regular part of healthcare. Vaccines are usually given to babies and young
children so that they are protected from diseases as soon as possible. Vaccines
exist for many diseases, including chicken pox, measles, mumps, rubella, polio,
diphtheria, tetanus, and whooping cough.
Some of these vaccines are given to almost
everyone. Others are given only to people who are considered likely to get the
disease, perhaps because of where they live or their age. Several vaccines may
be given at the same time as a combined vaccine. For example, the MMR vaccine
protects against measles, mumps, and rubella.
Some vaccines only make you immune for a few months
or years. They include vaccines against typhoid fever, cholera, tetanus, and
yellow fever. They may need a “booster” dose later to keep up the immunity.
PROBLEMS WITH VACCINES
Sometimes giving a vaccine to a person may cause
health problems. These problems are known as side effects, and they can be
serious. People who have certain illnesses and conditions are more likely to
have side effects. So medical workers ask questions about health before giving
vaccines. Once in a while, they advise people not to get vaccinated. Medical
workers must balance the risks of catching the disease with the risks of
possible side effects of vaccination.
CHANGING VIRUSES
Viruses can change, or mutate, over time. A vaccine
against one strain of a mutated virus may not work against another strain. The
flu (influenza) is one of these viruses that mutate into different strains. A
new vaccine for the flu has to be developed every year.
Every now and then a new kind of germ
appears. One example is HIV (human immunodeficiency virus), which causes a
disease called AIDS (acquired immune deficiency syndrome). No one knew about
HIV until the 1980s. When new viruses appear, medical scientists try to develop
new vaccines against them. It is a long and difficult process. But vaccination
is one of our most powerful medical weapons in the battle against diseases.
