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article imageEssential Science: How the coronavirus vaccines were developed

By Tim Sandle     Jan 11, 2021 in Science
Currently there are six COVID-19 vaccines for which certain national regulatory authorities have authorized the use. There are many potential COVID-19 vaccine candidates currently in development. How are these vaccines developed?
In 2019, a novel coronavirus was detected (SARS-CoV-2), which became the responsible agent for a global pandemic, triggering the disease COVID-19 in many of the individuals who became infected. This led to a hunt for vaccine candidates. Vaccine treatment is an effective method to prevent infection or improve the severity of diseases. In the other hand, vaccines serve as therapeutic and prophylactic agents to combat any infection.
A 3D print of a spike protein of SARS-CoV-2  the virus that causes COVID-19 -- in front of a 3D prin...
A 3D print of a spike protein of SARS-CoV-2, the virus that causes COVID-19 -- in front of a 3D print of a SARS-CoV-2 virus particle
Handout, National Institutes of Health/AFP
A vaccine specifically developed for COVID‑19 is concerned with developing a drug product to provide acquired immunity against COVID-19. One reason why vaccines are able to be developed at a faster pace compared with other emerging and dangerous pathogens, such as Ebola, is because research into vaccines against other coronavirus diseases, like the original SARS, and the MERS viruses, had already been established. This provided virologists with starting knowledge about the structure and function of coronaviruses.
The six approved vaccines
By approved vaccines, this means a vaccine that has been approved by at least one national regulatory authority. This means that the vaccine is approved for use within a certain country, it is not the same a global approval or approval by the World Health Organization.
US Vice President-elect Kamala Harris received her Covid-19 vaccine live on television
US Vice President-elect Kamala Harris received her Covid-19 vaccine live on television
Alex Edelman, AFP
Of the six vaccines, two of them are RNA vaccines (tozinameran from Pfizer–BioNTech and mRNA-1273 from Moderna). A further two are conventional inactivated vaccines (BBIBP-CorV from Sinopharm and CoronaVac from Sinovac). The final two are viral vector vaccines (Gam-COVID-Vac from the Gamaleya Research Institute and AZD1222 from the University of Oxford and AstraZeneca).
Vaccine challenges
One of the main challenges presented to scientists was how to handle the enhanced diseased condition occurring in immunized animals upon exposure to the virus. The development of vaccines needs to take a long time, involving virus strain isolation and selection, in vitro experiments, animal experiments, clinical trials, and then to gain regulatory approval.
The first step in the vaccine research includes designing the target product profile to guide the formulators. Animal model development, assay development, vaccine trial design, manufacturing processes are the critical areas of research in the “safe and effective” vaccine development.
More than 73 000 people in the Chinese capital have received the first dose of the vaccine
More than 73,000 people in the Chinese capital have received the first dose of the vaccine
STR, AFP
With developing the vaccine against the coronavirus, a list of vaccine candidates was developed, outfling potential candidates to combat COVID-19. A total of 50 vaccines were taken forward, globally, to the clinical trial phase. Among these, 11 vaccines are in Phase III clinical trial, 3 vaccines are in Phase II clinical trial, 13 vaccines are in Phase I/II clinical trial, and 21 vaccines are in Phase I clinical trial.
Clinical trial phases
There are different phases of clinical trials. The different steps are summarized below.
Preclinical: Testing of drug in non-human subjects to gather efficacy, toxicity and pharmacokinetic information.
Phase 0: Pharmacokinetics; particularly oral bioavailability and half-life of the drug.
Phase I: Dose-ranging on healthy volunteers for safety.
Phase II: Testing of drug on participants to assess efficacy and side effects.
Phase III: Testing of drug on participants to assess efficacy, effectiveness and safety.
Phase IV: Post marketing surveillance in public.
Types of vaccines
Inactivated vaccines, recombinant protein vaccines, adenovirus vector vaccines, attenuated influenza virus vector live vaccines, and nucleic acid vaccines against SARS-CoV-2 are the types of vaccine in development. Inactivated vaccines are generally considered to be the most effective path of vaccine development for newly emerging infectious diseases.
The Amsterdam-based European Medicines Agency (EMA) has yet to approve Moderna's coronavirus va...
The Amsterdam-based European Medicines Agency (EMA) has yet to approve Moderna's coronavirus vaccine
Joseph Prezioso, AFP/File
The vaccines target the spike (S) protein, which is one the 'corona' protrusion from the virus surface, and its variants as the primary antigen. The S-protein is the mechanism by which the virus attaches to the cells of the human lung.
How can vaccines be developed so quickly?
Vaccines typically require years of research and testing before reaching the clinic, but in 2020, scientists embarked on a race to produce safe and effective coronavirus vaccines in record time. On November, 12, 2020, researchers are testing multiple vaccines in different clinical trials phase.
France's vaccine rollout has been criticised for being too slow
France's vaccine rollout has been criticised for being too slow
JOEL SAGET, AFP
Both the Pfizer and Moderna's COVID-19 vaccines, though, took 10 months to be developed and distributed after the previous record had been four years for a mumps vaccine. The understanding that went into the new vaccines can be rolled out to assist with accelerating future vaccine development.
This was due to the use of animal models, learnings from other coronaviruses, better protocols, and an unprecedented series of collaborations between governments, pharmaceutical firms and academic medical centers.
So far over 250 000 people have received the first vaccine shot in Germany
So far over 250,000 people have received the first vaccine shot in Germany
Soeren Stache, POOL/AFP
Animal models, mimic aspects of a diseased condition found in humans are used to evaluate the disease. To evaluate the potential of vaccines, standardized animal models are developed in order to understand the enhanced disease after vaccination. Therefore, a validated animal model is used to extrapolate human conditions before large scale efficacy studies. In addition, development and standardization of assay, in supporting the immune responses and clinical case to support the research in vaccine development, was undertaken.
In parallel, the manufacturing processes required to rapidly enable the production of high-quality large quantities of clinical grade and pharmaceutical standard materials took place in order to take the successful vaccines to scale.
Vaccine approval
The approval of vaccines is only granted by a national regulator once data has been presented and the data has been assessed to determine that the vaccine is both safe and efficacious. National regulators include the Food and Drug Administration (US), Health Canada, and the Medicines and Healthcare products Regulatory Agency (MHRA, in the UK).
Blandine Johannel  a mursing home resident  receives a dose of the Pfizer-BioNTech Covid-19 vaccine ...
Blandine Johannel, a mursing home resident, receives a dose of the Pfizer-BioNTech Covid-19 vaccine during a vaccination campaign in Vannes, western France on January 7, 2021
LOIC VENANCE, AFP
Vaccine roll out
Bahrain was the first country in the world to approve one of the vaccines to come from an established pharmaceutical company (that is, not the Russian variant). To assess the roll out of vaccines, the website Our World Data has interactive maps showing the proportion of each country's population that have been vaccinated.
Essential Science
This article forms part of Digital Journal’s long-running Essential Science series, where new research items relating to wider science stories of interest are presented by Dr. Tim Sandle on a weekly basis.
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