Introduction to Vaccines
Rheem A. Totah, PhD
Medicinal Chemistry, School of Pharmacy
Questions we will answer today:
• What are vaccines? How are they different from
drugs? Is it necessary to vaccinate?
• What are the types of vaccines? Focus on flu
and potential COVID-19 vaccine.
• What are the components of vaccines?
• What are some of the reasons for vaccine
refusal especially for flu?
What are vaccines?
The WHO defines vaccines as:
“A biological preparation that improves immunity to a particular disease.
A vaccine typically contains an agent that resembles a disease-causing
microorganism, and is often made from weakened or killed forms of the
microbe, its toxins or one of its surface proteins. The agent stimulates
the body’s immune system to recognize the agent as foreign, destroy it,
and “remember” it, so that the immune system can more easily
recognize and destroy any of these microorganisms that it later
Vaccines focus on your immune system
Vaccines vs. Drugs
Vaccines are very different than drugs:
• It is expensive and difficult to get vaccines approved.
• Drugs go to a small number of sick people who need them.
• Vaccines are administered to millions of healthy people to help them not get sick.
• With diseases becoming rare, the focus is more on the vaccine than the disease
• Public confidence in vaccine safety is more critical than drugs
– higher standard of safety is expected of vaccines
Why Do We Vaccinate?
Some diseases do not have drug treatments, or any other treatment, and have
been well controlled with vaccinations.
The Concept of Herd Immunity
• Live attenuated vaccine.
• Killed vaccines or segmented vaccines
• Polysaccharide and conjugated vaccines
• Virus Like Particle Vaccines
• DNA and RNA vaccines
Types of Vaccines
• 100% effective
• Oral dosage form
• No adverse effects
• Highly immunogenic
life-long immunity from a single dose
no boosters required
• Stable at room temperature
The Perfect Vaccine
What is in a vaccine?
Vaccines have :
– Antigenic material, weakened/killed virus or bacteria
-Stabilizers (mono sodium glutamate, 2-phenoxy
– Adjuvants (increase immune response)
– Preservatives (prevent fungal and bacterial growth)
(e.g antibiotics, formaldehyde and in
some cases thimerosal)
Are Vaccines Safe?
No vaccine is 100 percent safe. Almost all vaccines can
cause pain, redness or tenderness at the site of injection.
Some vaccines cause more severe side effects.
However, the danger (the disease) must be significantly
greater than the means of protecting against the danger
(the vaccine). In other words, a vaccine’s benefits must
clearly and definitively outweigh its risks.
Established in 1990, the Vaccine Adverse Event Reporting
System (VAERS) is a reporting system to CDC that
records adverse events reported in the US.
Flu Season and Flu Vaccine
• Highly infectious viral illness
• First pandemic in 1580
• At least 4 pandemics in 19th century
• Estimated 21 million deaths worldwide in
pandemic of 1918-1919
• Virus first isolated in 1933
– secondary bacterial
– primary influenza viral
• Reye syndrome
• Death 0.5-1 per 1,000 cases
How is the flu vaccine prepared?
It is recommended that quadrivalent vaccines for use in the 2019-
2020 northern hemisphere influenza season contain the following:
an A/Guangdong-Maonan/SWL1536/2019 (H1N1) pdm09-like virus;
an A/HongKong/2671/2019 (H3N2)-like virus;
a B/Washington/02/2019- like virus (B/Victoria lineage);
a B/Phuket/3073/2013-like virus (B/Yamagata lineage).
Flu Vaccine Myths or Facts
• The Flu is not serious it is just like a bad cold.
• Only at risk among the population should get the flu vaccine (>65, pregnant,
• It is better to get the flu than to get the flu vaccine.
• You can get the flu from the vaccine.
• It is better to get the vaccine early in the season to be protected throughout
• You can skip years when getting the flu vaccine.
Reasons for Vaccine Refusal
Personal Beliefs or Philosophical
Safety Concerns, some still
the study published in the 1980s
Desire for Additional Education
Vaccines and other treatments for COVID-19
Work is progressing quickly to find a treatment and a vaccine for
In terms of vaccines, clinical trials in Seattle is underway to test the
safety of an RNA vaccine against SARS-CoV-2. Many other vaccine
trials around the world working on DNA vaccines or isolating viral
proteins that can serve as antigens.
Monoclonal antibodies are usually isolated from patients who have
recovered from COVID-19 and administered to patients fighting the
disease. The idea is that it will boost your body’s immune response
to help fight the virus and prevent serious complications.
Remdesivir is an adenosine analog prodrug developed by Gilead Sciences. It inhibits viral RNA dependent RNA polymerase and results in chain termination. It is active against several RNA viruses and showed promise against SARS and MERS.
It has received approval and was used to treat a patient in Snohomish county. The drug improved the clinical condition of the first patient infected by SARS-CoV-2 in the US, and a phase III clinical trial of remdesivir against SARS-CoV-2 was launched in Wuhan on February 4, 2020. So far the data is promising.