Talking about currently developed COVID-19 vaccines and how they work.

1. COVID-19 Vaccine
PRESENTED BY AYAAT A. KADHUM

2. Introduction
The novel coronavirus, named Severe Acute Respiratory Syndrome coronavirus 2
(SARS-CoV-2), it was identified as the cause of an outbreak of respiratory illness first
detected in Wuhan, China in 2019. The illness caused by this virus has been named
coronavirus disease 2019 (COVID-19).
It is an airborne virus and can transmitted directly through respiratory droplets when
non infected people are in close contact (less than 1 meter apart) with an infected
person in a similar way to the cold and influenza.
COVID-19 can also transmitted indirectly by touching the surface or object that has the
virus on it and then touching their own mouth, nose, or eyes. Spread from touching
surfaces is not thought to be the main way the virus spreads, some evidence showed
that droplets and airborne particles can remain suspended in the air and be breathed in
by others.

3. Vaccines
Vaccines greatly reduce the risk of infection by training the immune system to recognize
and fight pathogens such as viruses or bacteria by providing an active acquired
immunity against infectious diseases and they can only be developed when the
infectious agent is known.
Vaccines are urgently needed to control the coronavirus disease 2019 (COVID-19)
pandemic and to help the return to pre-pandemic normalcy. A great many vaccine
candidates are being developed, several of which have completed late-stage clinical
trials and are reporting positive results.
Since SARS-CoV-2 is a new virus that had not been seen before, development of a
vaccine to protect against COVID-19 could only be started once the virus emerged and
its genetic make-up had been analyzed.

4. Vaccines
There are four major structural proteins for this virus, including the spike surface (S)
glycoprotein (functionally divided into the S1 domain, responsible for receptor binding,
and the S2 domain, responsible for cell membrane fusion), small envelope protein (E),
matrix protein (M), and nucleocapsid protein (N).
The spike surface glycoprotein plays an essential role in binding to receptors on the host
cell and is crucial for determining host tropism and transmission capacity, mediating
receptor binding and membrane fusion .

5. Structure of severe acute respiratory syndrome coronavirus 2

6. This virus can enter the human body through its receptors,The process of entering
into the host cell begins through the attachment of the S glycoprotein to the receptor,
the ACE2 in the host cells.This attachment occurs in the binding domain of S protein
of SARS-CoV-2 receptors and can bind strongly to human ACE2. The entry and
binding processes are then followed by fusion of the viral membrane and host cell.

7. Types of Vaccines
Currently, there are three main types of COVID-19 vaccines, each type of vaccine
speeds our body’s responses to recognize and protect us from the virus that causes
COVID-19.
1.mRNA vaccines contain material from the virus that causes COVID-19 that gives our
cells instructions for how to make a harmless protein that is unique to the virus. After our
cells make copies of the protein, they destroy the genetic material from the vaccine. Our
bodies recognize that the protein should not be there and build T-lymphocytes and B-
lymphocytes that will remember how to fight the virus that causes COVID-19 if we are
infected in the future.
2.Protein subunit vaccines include harmless pieces (proteins) of the virus that cause
COVID-19 instead of the entire germ. Once vaccinated, our immune system recognizes
that the proteins don’t belong in the body and begins making T-lymphocytes
and antibodies. If we are ever infected in the future, memory cells will recognize and
fight the virus.

8. Types of vaccines
3.Vector vaccines contain a weakened version of a live virus—a different virus than the
one that causes COVID-19—that has genetic material from the virus that causes
COVID-19 inserted in it (this is called a viral vector). Once the viral vector is inside our
cells, the genetic material gives cells instructions to make a protein that is unique to the
virus that causes COVID-19. Using these instructions, our cells make copies of the
protein. This prompts our bodies to build immune cells that will fight that virus when the
body is infected.
COVID-19 vaccines are developed following the same legal requirements for
pharmaceutical quality, safety and efficacy as other medicines.
Like all medicines, COVID-19 vaccines’ effects are first tested in laboratory, including in
animals, then vaccines are tested in human volunteers.

9. Steps in vaccine development
•Pre-clinical studies: Vaccine is tested in animal studies for efficacy and safety, including
challenge studies.
•Phase I clinical trial: Small groups of healthy adult volunteers receive the vaccine to test
for safety.
•Phase II clinical trial: vaccine is given to people who have characteristics (such as age
and physical health) similar to those for whom the new vaccine is intended.
•Phase III clinical trial: Vaccine is given to thousands of people and tested for efficacy and
safety.
•Phase IV: post marketing surveillanceOngoing studies after the vaccine is approved and
licensed, to monitor adverse events and to study long-term effects of the vaccine in the
population.

10. Vaccines in Advanced Stage
1. AZD1222: is a COVID-19 vaccine candidate administrated by intramuscular injection,
that is developed by Oxford University, it is a replication-deficient simian adenovirus
vector, containing the coding sequence of SARS-CoV-2 spike protein along with a tissue
plasminogen activator (tPA) leader sequence. The modified monkey adenovirus cannot
replicate, so does not cause further infection, and instead acts as a vector to transfer the
SARS-CoV-2 spike protein, After vaccination the spike protein is produced, promoting
the immune system to attack the coronavirus if it later infects the body.
2. mRNA-1273: The Moderna vaccine still unapproved vaccine that may prevent COVID-
19. It is administered by intramuscular injection , once the instructions (mRNA) are
inside the immune cells, the cells use them to make the protein piece then the cell
breaks down the instructions and gets rid of them. Next, the cell displays the protein
piece on its surface which is recognized by the immune system and begin building an
immune response and making antibodies, like what happens in natural infection against
COVID-19.

11. Vaccines in Advanced Stages
3. BNT162b2: an mRNA-based vaccine candidate, against SARS-CoV-2 has been
developed by Pfizer and BioNTech.Based on evidence from clinical trials, the Pfizer-
BioNTech vaccine was 95% effective at preventing laboratory-confirmed COVID-19
illness in people without evidence of previous infection.It requires two shots a priming
dose, followed by a booster shot. The most common side effects are injection site pain,
fatigue, headache, muscle pain, and joint pain. Some people in the clinical trials have
reported fever. Side effects are more common after the second dose; younger adults,
who have more strong immune systems, reported more side effects than older adults.

13. Common Questions
Can vaccinated people get infected with the virus?
It typically takes a few weeks for the body to build immunity after vaccination. That means it’s possible a
person could be infected with the virus that causes COVID-19 just before or just after vaccination and
get sick. This is because the vaccine has not had enough time to provide protection.
Do some people feel bad after getting Covid vaccine?
Yes, the COVID-19 vaccine might make you feel ill. That means it's working. The COVID-19 mRNA
vaccines work by eliciting an immune response. That comes with some temporary side effects, like
muscle aches or fever.
Can vaccinated people transmit the disease?
The vaccine will protect you from getting ill and then ending up hospitalized. But it's possible that you
could still carry the virus and be contagious to others. So those who get the vaccine should still be
wearing masks and practicing physical distancing.

14. Conclusions
The idea of a vaccine against SARS-CoV-2 in a fast-spreading pandemic has great
allure. The sheer variety of the novel types of vaccines being investigated and the
approaches they use, whatever form that takes, could serve us well for future outbreaks
of other novel diseases.
At this point, it remains unclear how effective a COVID-19 vaccine will be. Even if a
promising vaccine surfaces by 2021 and can be mass-produced, the search will not end
there. We are likely to need more than one vaccine to meet global demand.Of
importance, if SARS-CoV-2 remains a threat to a few, it will remain a threat to everybody.

15. References
1. Johns Hopkins University Coronavirus Resource Center. COVID-19 dashboard by
the Center for Systems Science and Engineering (CSSE) at Johns Hopkins
University. 2020
2. Pardi N, Tuyishime S, Muramatsu H, et al. Expression kinetics of nucleoside-modified
mRNA delivered in lipid nanoparticles to mice by various routes. J Control
Release 2015;217:345-351.
3. https://www.fda.gov/vaccines-blood-biologics/development-approval-process-
cber/vaccine-development-101
4. Centers for Disease Control and Prevention. COVID-19 information
5. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html

16. Thank you!