COVID-19 has infected more than 27 million people globally resulting in an untold number of tragic and premature deaths. As we move into autumn, scientists are predicting a second and perhaps even a third wave of the virus could sweep through the world’s populations.
Stopping the spread of the virus and saving lives is dependent upon initiating herd immunity in the general population through the development and administration of a safe and effective vaccine…so where are we in these efforts?
The following article by Burra based professor Deborah Briggs provides an overview of the progress made to date and concludes that a safe and effective vaccine could become available in the near future.
DIFFERENT research teams, manufacturers and sponsors throughout the world have been using various types of vaccine platforms to develop potential Covid-19 vaccines. This means that several different types of Covid-19 vaccines will be entering the global market in the next months to years.
Some of the researchers working on Covid-19 vaccines are using older types of technologies, such as inactivated vaccines, and some researchers are using the very latest technologies including mRNA-lipid-encapsulated vaccines. Whatever type of technology is being used to develop a Covid-19 vaccine, all vaccine producers need to adhere to specific regulations regarding the development process in order to ensure that their vaccine is safe and effective for use in humans.
Each new candidate Covid-19 vaccine must be evaluated for safety, immunogenicity and for its ability to protect humans against disease before it is licensed for use in humans.
There are three phases in the development process and each phase is briefly described below.
The first phase includes the first administration of the candidate vaccine into a small number of healthy human volunteers. The primary objective of phase 1 is to evaluate the safety and reactogenicity of the candidate vaccine. A secondary objective is to collect data on the immune response to the vaccine. Additionally, in phase 1 researchers may investigate various doses and potential schedules for the candidate vaccine.
Upon successful completion of phase 1, the candidate vaccine will move into phase 2 of clinical development. Phase 2 will include administering the vaccine to a much larger number of volunteer human subjects. The primary objective of phase 2 is to evaluate the safety and immune response of the candidate vaccine in a large enough number of human subjects to provide clinically meaningful data.
Normally, this means that hundreds to thousands of human volunteers will receive the candidate vaccine and any and all adverse reactions and immune responses will be closely monitored. Phase 2 is usually conducted in settings where there is a high incidence of disease.
Upon successful completion of phase 2, the candidate vaccine will move into phase 3 of clinical development. The primary objective of phase 3 is to evaluate the efficacy and safety of the candidate vaccine in tens to hundreds of thousands of human subjects.
In phase 3, participants will receive either the candidate vaccine or a placebo (a harmless substitute saline solution), or in some cases another type of vaccine. Phase 3 clinical trials are conducted in different age groups and in ‘field’ conditions in different settings where the disease is evident.
Data collected from phase 3 is evaluated for safety and to determine if there was a reduction in disease incidence in those individuals that received the candidate vaccine, and if so by how much.
Help for nations unable to develop their own Covid-19 vaccine(s)
At the present time, there are several international health organisations, including the World Health Organisation, that are working together with vaccine manufacturers to be able to provide low-cost Covid-19 vaccines to countries in need when one or more Covid-19 vaccines have completed phase 3 of the clinical process and come to market.
Additionally, a few international foundations are funding research and development projects aimed at developing a safe and effective Covid-19 vaccine. The government of the US has funded three specific vaccine candidates for phase 3 clinical trials under a programme that they have labelled “Operation Warp Speed”. One of the vaccines that has received funding through this programme is the being developed by the University of Oxford/Jenner Institute in the UK.
Candidate vaccines in development
There are more than 140 candidate Covid-19 vaccines in various stages of development throughout the world. As of the beginning of September 2020, a handful of these Covid-19 candidate vaccines have initiated or are just about to initiate phase 3 clinical trials.
Additionally, there is one Covid-19 vaccine, produced in Russia that was recently licensed for use in Russia.
On 11 August 2020, the first Covid-19 vaccine for use in humans was approved by the ministry of health in the Russian Federation for use in Russia. This vaccine is a viral vector vaccine known as Sputnik V.
Global public health experts are highly concerned about the safety and efficacy of this vaccine because it has not entered the all important Phase 3 clinical trials and therefore there are no published, peer reviewed data available for review.
Without data from Phase 3 clinical trials, it is impossible to evaluate the safety and effectiveness of the vaccine.
Three Covid-19 vaccines under development by Chinese researchers
There are three candidate Covid-19 vaccines in phase 3 development in China. The Wuhan Institute in China was the first research group to start phase 3 clinical trials on a Covid-19 vaccine. Their vaccine is an inactivated vaccine. The sponsoring pharmaceutical group for this vaccine, China National Pharmaceutical Group (SinoPharm), have indicated that they expect the vaccine to be ready by the end of 2020.
The second Covid-19 vaccine, known as CoronaVac, in phase 3 development in China is an inactivated vaccine from the Sinovac Research and Development Co. Ltd. The phase 3 clinical trials are underway in at least three countries: China, Brazil and Indonesia.
The third Covid-19 under development in China is a viral vector vaccine known as Ad5-nCoV. It is being sponsored by CanSino Biologics and is entering phase 3 clinical trials in at least two countries: China and Saudi Arabia.
The Oxford University/Jenner Institute
The Covid-19 candidate vaccine under development by the University of Oxford/Jenner Institute, Astra Zeneca and other partners is a viral vector vaccine known as AZD1222/Covishield.
This group expects to enroll up to 50,000 participants throughout the world including volunteers in the UK, South Africa, USA and India. Results from phase 3 are expected to be made available later this year.
This group received over one billion US dollars in funding from the US for phase 3 clinical trials and has also received major funding from the UK government.
This vaccine, known as mRNA-1273, is being developed by several research institutes including: the biotech company Moderna, Inc. and the National Institute of Allergy and Infectious Diseases in the US.
This group also received over one billion US dollars in funding from the US for phase 3 clinical trials that began at several sites in the US in July 2020. The vaccine is a novel lipid nanoparticle (LNP)-encapsulated mRNA-based vaccine.
Pfizer Covid-19 candidate vaccine
This vaccine, known as BNT162, is being developed by the pharmaceutical company Pfizer and has received over 1 billion US dollars from the American government in support of phase 3 clinical trials.
The vaccine is a novel lipid nanoparticle (LNP)-encapsulated mRNA-based vaccine. Pfizer has stated that assuming clinical success, they will supply up to 100 million doses worldwide by the end of 2020.
When to expect a safe and effective Covid-19 vaccine
At this point, we will have to wait to see what the data from the phase 3 clinical trials look like and how effectively these vaccines protect against Covid-19.
However, the number of candidate vaccines listed above that have completed phase 2 successfully and are now starting or are already into phase 3 indicates that there will be safe and effective Covid-19 vaccines available in the very near future.
Stay tuned – hopefully we will have more information about the data from phase 3 in the next few months.
Professor Deborah Briggs has served as an expert to the World Health Organisation in the field of rabies prevention. She has provided expertise in the field of vaccine production and clinical trials for major pharmaceutical companies and continues to teach an online graduate level course in Global Public Health for Kansas State University. She lives in Bridge End, Burra.
More detailed information about the clinical phases of vaccine development can be found at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4944327/
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