Covid-19 vaccines

Covid-19 vaccines

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  COVID-19 Vaccine PRESENTED BYAYAAT A. KADHUM
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  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.
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  Vaccines Vaccines greatly reducethe 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.
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  Vaccines There are fourmajor 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 .
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  Structure of severeacute respiratory syndrome coronavirus 2
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  This virus canenter 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.
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  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.
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  Types of vaccines 3.Vectorvaccines 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.
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  Steps in vaccinedevelopment •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.
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  Vaccines in AdvancedStage 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.
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  Vaccines in AdvancedStages 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.
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  Common Questions Can vaccinatedpeople 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.
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  Conclusions The idea ofa 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.
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  References 1. Johns HopkinsUniversity 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
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  Thank you!