Latest Updates on Vaccines

The race for coronavirus vaccines: a graphical guide

https://www.nature.com/articles/d41586-020-01221-y

• More than 90 vaccines are being developed against SARS-CoV-2 by research teams in companies and universities across the world
• At least six groups have already begun injecting formulations into volunteers in safety trials; others have started testing in animals

How we develop immunity?

• The body’s immune system learns to recognize invading pathogens
• The coronavirus, SARS-CoV-2, enters the body’s cells via the attachment of its spike protein to the ACE2 receptor on the cell membrane
• Once inside, the cell translates the virus’ RNA to produce more viruses
• As virus is released from the cell it is ingested by Antigen Presenting Cells (APCs) which show portions of the virus to helper T cells
• Helper T cells enable other immune responses:
  • B cells: they make antibodies that block the virus from infecting cells and also mark the virus for destruction
  • Cytotoxic T cells: they identify virus infected cells and destroy them
• Long-lived memory B and T cells can recognize the virus and patrol the body for months, or even years, thereby providing immunity

SARS-CoV-2 vaccines approaches

• All vaccines aim to expose the body to an antigen that won’t cause disease, but will provoke an immune response that can block or kill the virus if a person becomes infected
• There are at least eight types being tried against the coronavirus, and they rely on different viruses or viral parts

Types of Vaccine Candidates

1. Virus – (1) inactivated or (2) weakened
2. Viral vector – (1) replicating or (2) non-replicating
3. Nucleic acid – (1) DNA or (2) RNA
4. Protein-based – (1) protein subunit or (2) virus-like particles
5. Virus Vaccines: At least seven teams are developing vaccines using the virus itself, in a weakened or inactivated form. Many existing vaccines are made in this way, such as those against measles and polio, but they require extensive safety testing.

Virus

(1) Inactivated virus

• In these vaccines the virus is rendered uninfectious using chemicals such as formaldehyde or heat
• However, making these kind of vaccines require large quantities of infectious virus

(2) Weakened virus

• In this method, the virus is conventionally weakened by passing through animal or human cells where it undergoes several mutations to finally become less able to cause disease
• Codagenix, Farmingdale NY is working with Serum Institute of India to weaken SARSCoV2 by altering its genetic code so that viral proteins are produced less efficiently

Viral Vector

Around 25 groups say they are working on viral vector vaccines. A virus such as measles or adenovirus is genetically engineered so that it can produce coronavirus proteins in the body. These viruses are weakened so they cannot cause disease.

(1) Replicating viral vector

• The newly approved Ebola vaccine is an example of a viral vector vaccine that replicates within cells
• Such vaccines tend to be safe and provoke a strong immune response

(2) Non-replicating viral vector

• No licensed vaccines use this method, but they have a long history in gene therapy
• Booster shots can be needed to induce long lasting immunity

Nucleic Acid Vaccines

At least 20 teams are aiming to use genetic instructions (in the form of DNA or RNA) for a coronavirus protein that prompts an immune response. The nucleic acid is inserted into human cells, which then churn out copies of the virus protein. RNA and DNA-based vaccines are safe and easy to develop but they are unproven as no licensed vaccines use this technology.

Protein-Based Vaccines

Many researchers want to inject coronavirus proteins directly into the body. Fragments of proteins or protein shells that mimic the coronavirus’ outer coat can also be used.

(1) Protein subunits

• Twenty eight teams are working on vaccines with viral protein subunits — most of them are focusing on the virus’s spike protein
• Similar vaccines against the SARS virus protected monkeys against infection but haven’t been tested in people

(2) Virus-like particles

• Empty virus shells mimic the coronavirus structure, but aren’t infectious because they lack genetic material
• Five teams are working on ‘viruslike particle’ (VLP) vaccines

Strategies for Vaccine Development of COVID-19

https://pubmed.ncbi.nlm.nih.gov/32347054

An epidemic of acute respiratory syndrome in humans, which appeared in Wuhan, China in December 2019, was caused by a novel coronavirus (SARS-CoV-2). This disease was named as “Coronavirus Disease 2019” (COVID-19). SARS-CoV-2 was first identified as an etiological pathogen of COVID-19, belonging to the species of severe acute respiratory syndrome-related coronaviruses (SARSr-CoV). The speed of both the geographical transmission and the sudden increase in numbers of cases is much faster than SARS and Middle East respiratory syndrome (MERS). COVID-19 is the first global pandemic caused by a coronavirus, which outbreaks in 211 countries/territories/areas. The vaccine against COVID-19, regarded as an effective prophylactic strategy for control and prevention, is being developed in about 90 institutions worldwide. The experiences and lessons encountered in the previous SARS and MERS vaccine research can be used for reference in the development of COVID-19 vaccine. The present paper hopes to provide some insights for COVID-19 vaccines researchers.

Vaccine Designers Take First Shots at COVID-19

https://science.sciencemag.org/content/368/6486/14.long

Developing a vaccine for covid-19

https://www.bmj.com/content/369/bmj.m1790.long

The COVID-19 vaccine development landscape

https://www.nature.com/articles/d41573-020-00073-5

Possible treatment of Covid-19 with a therapeutic vaccine

https://veterinaryrecord.bmj.com/content/186/13/419.1.long

A single dose of ChAdOx1 MERS provides protective immunity in rhesus macaques

https://advances.sciencemag.org/content/early/2020/04/30/sciadv.aba8399?utm_campaign=SciMag&utm_source=JHubbard&utm_medium=Twitter

Australia set for Chinese COVID-19 vaccine human trial

https://www.aa.com.tr/en/asia-pacific/australia-set-for-chinese-covid-19-vaccine-human-trial-/1821328

A spike with which to beat COVID-19?

https://www.nature.com/articles/s41579-020-0383-2

Coronavirus vaccine from Moderna shows early signs of viral immune response

https://gulfnews.com/world/americas/coronavirus-vaccine-from-moderna-shows-early-signs-of-viral-immune-response-1.1589804309568