Microbiology

Running head: MICROBIOLOGY
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Microbiology
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MICROBIOLOGY
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Herd immunity
‘Herd immunity’ according to the World Health Organization, is the immunization of a
significant proportion of a population as a measure to protect individuals who have not
developed immunity and are at risk of infection from the particular disease or condition (Metcalf,
Ferrari, Graham, & Grenfell, 2015). Herd immunity is effective when majority of the people are
protected by vaccination against either a bacteria or virus making it quite impossible for the
disease to spread since the proportion of vulnerable people left is low.
It is one of the best approach to prevent spread of diseases in particular communities.
Studies acknowledge that is pivotal when protecting people who cannot be immunized. Some of
the people who cannot be vaccinated include children who are so young to be immunized,
individuals with compromised immune system and finally, those people who are too sick to be
immunized like some cancer patients. However, Betsch, Böhm, Korn, & Holtmann argue that the
percentage of the population that should be immunized to achieve herd immunity vary depending
with the disease to be prevented (Betsch, Böhm, Korn, & Holtmann, 2017). This means that the
proportion of population to be immunized to achieve herd immunity in influenza for example, is
different from the population to be immunized to prevent measles. Relevant stakeholders should
ensure that the proportion of those vaccinated remains relatively high throughout since a
breakdown in immunization rates subsequently breaks down herd immunity thus increasing the
incidence of the infection (Mallory, Lindesmith, & Baric, 2018). A good example is the outbreak
of measles in UK and pertussis in the United States of America.

MICROBIOLOGY
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How immunization protect the body against a particular disease
Scientists acknowledge that development of vaccines is one of the greatest achievements
in healthcare. Vaccines have made it possible to eliminate serious infections like smallpox as
well as eliminating 95% of common childhood infections like diphtheria, measles as well as
polio. However, studies note that despite the advancements, 1.5 million people die globally as a
result of vaccine preventable diseases (Sprochi, 2018). Vaccines work in a very unique way.
Vaccines are basically inactivated form of the pathogen or disease. Once they are introduced into
the body, the body produces antibodies against the vaccine. Memory cells then develop such that
when the vaccinated individual comes into contact with the pathogen, the antibodies fight back
even before the infection is manifested thereby preventing the vaccinated individual from a
similar pathogen.
Importance of antigenic drift and antigenic shift in influenza virus for human
diseases
The influenza viruses are rapidly changing through two different ways. The two are
antigenic drift and antigenic shift. Antigenic drift refers to small changes in the genes that make
up the influenza viruses. This is a continuous process that takes place as the virus replicates. The
genetic changes leads to production of viruses that are closely related to another (Kim, Webster,
& Webby, 2018). The new viruses are located close to each other as shown by the phylogenetic
tree. Since the new viruses share common antigenic properties, it becomes easier for the immune
system to combat them if at all they had encountered a similar virus previously. This
phenomenon is described by scientists as cross protection.