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COVID-19 UPDATE

COVID-19 Vaccination

Overview:

From the Beginning to Present

By Alan M. Preston, MHA, ScD

The virus that causes COVID-19 is related
to other coronaviruses. The good news is that
scientists have been studying coronaviruses
for years and there is a lot we have learned.
Severe Acute Respiratory Syndrome (SARS)
and Middle East Respiratory Syndrome
(MERS) are not new, and vaccinations have
been developed for previous strains. Never-
theless, each strain requires a specific vaccine
to combat the RNA makeup of such strain
in order to be an effective vaccine. Currently,
there are three approved vaccines:

1. Pfizer-BioNTech: for ages 12 years and
older and needs 2 shots given 3 weeks (21
days) apart.

2. Moderna: for ages 18 years and older and
needs 2 shots given 4 weeks (28 days)
apart.

3. Johnson & Johnson’s Janssen: for ages 18 phases have been skipped. These three pre- the candidate vaccine and determine the type
years and older and needs 1 shot. liminary clinical trials must be performed to and extent of immune response that the vac-
obtain approval from the FDA: cine provokes.
Vaccines go through three phases of clini-
cal trials to make sure they are safe and effec- 1. Phase I Vaccine Trials 2. Phase II Vaccine Trials
tive. For other vaccines routinely used in the This first trial involves a small group of A larger group of several hundred individ-
United States, the three phases of clinical tri- adults, usually between 20-80 subjects. If the uals participates in Phase II testing. Phase II
als are performed one at a time and do not vaccine is intended for children, researchers testing aims to study the individual vaccine’s
overlap, which is why the standard process is will first test adults and then gradually step safety, efficacy, proposed doses, schedule of
so lengthy. The third phase usually takes the down the age of the test subjects until they immunizations and delivery method.
longest. During the development of reach their target. This is one reason that the
COVID-19 vaccines, these phases have over- age limits for children are in place. The goals 3. Phase III Vaccine Trials
lapped to speed up the process. No trial of Phase 1 testing are to assess the safety of Successful Phase II candidate vaccines

16 SAN ANTONIO MEDICINE • July 2021