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Marcos E. García-Ojeda, University of California, Merced
I, like many Americans, miss the pre-pandemic world of hugging family and friends, going to work, and dining at a restaurant. A protective SARS-Cov2 vaccine is likely to be the most effective public health tool to return to that world.
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, cautiously estimates that a vaccine could be available in 12 to 18 months.
I am a professor of microbiology and immunology and study how the immune system develops. I think Dr. Fauci’s estimate is optimistic, but possible.
Traditional vaccine development is a long and complicated process. Only about 6% of vaccine candidates are finally approved for public use, and the process takes an average of 10.7 years.
But these are not traditional times. Researchers from around the world are innovating the vaccine development process in real time to develop a vaccine as quickly as possible. So how close are we to a vaccine?
A step by step process.
Vaccines prevent disease by increasing a person’s natural immune response against a microbe they have not encountered before. There are several different types of vaccines in development for SARS-CoV-2 and they fall into three broad categories: traditional killed virus vaccines, protein-based vaccines, and gene-based vaccines. No matter the type, each vaccine candidate must go through the same research process before it can be put into use.
Once researchers have developed a potential candidate, they begin the first step of laboratory testing, called preclinical studies. Scientists use laboratory animals to examine whether the candidate vaccine induces an immune response to the virus and to verify whether the vaccine causes any obvious medical problems.
Once a vaccine is proven to be safe in animals, researchers begin human testing. This is where the Federal Food and Drug Administration begins to regulate the process.
Proof of phase 1 studies for safety and proof of concept. The researchers give the vaccine to a small number of human volunteers. Then they look for medical problems and see if it induces some kind of immune response.
In Phase 2 studies, researchers administer the vaccine to hundreds of volunteers to determine the optimal vaccine composition, dose, and vaccination schedule.
The final step before the FDA approves a vaccine for wide use is a phase 3 trial. These involve thousands of volunteers and provide data on how good the vaccine is at preventing infection. These large tests will also discover rarer side effects or health problems that may not show up on smaller tests.
If in any of these phases a vaccine candidate appears to be ineffective or cause harm to people, researchers must start again with a new candidate.
After a vaccine candidate successfully completes these clinical trials, a medical regulatory panel at the FDA reviews the evidence and, if the vaccine is effective and safe, approves it for general use. Experts estimate that the entire process costs between $ 1 billion and $ 5 billion.
But approval is not the only obstacle. As demonstrated by the severe lack of coronavirus testing, the quick and easy production of a test or vaccine is as critical as having one that works.
Both clinical efficacy and ease of production should be considered when asking how long until a vaccine is ready.
Current promising candidates
As of April 30, 2020, there were eight vaccine candidates currently in Phase 1 (or joint Phase 1 / Phase 2 clinical trials) and 94 vaccine candidates in preclinical studies.
Three of the eight are traditional vaccines that use killed or inactivated viruses. Two of the others are protein-based vaccines that use a modified cold virus to deliver the protein that will stimulate the immune response.
The final three vaccines in phase 1 or 2 trials, and the only two in the US. UU., They are vaccines based on genes. To me these seem to be the most promising.
Gene-based vaccines contain a gene or part of a gene from the virus that causes COVID-19, but not the virus itself. When a person is injected with one of these vaccines, their own cells read the injected gene and make a protein that is part of the coronavirus. This protein is not dangerous in itself, but it should trigger an immune response that would lead to immunity from the coronavirus.
Gene-based vaccines come in the form of DNA, as the vaccine in Phase 1 clinical trials of Inovio Pharmaceuticals in the United States, or as RNA, as the vaccine in a simultaneous Phase 1 / Phase 2 trial of the German company BioNTech and the vaccine in Modern Phase 1 Trials, based in the USA. USA
Gene-based vaccines have never been approved for human use, but DNA vaccines are used in animals, and some were in clinical trials for Zika virus.
In the past, researchers have had trouble developing DNA vaccines that produce strong immune responses, but the new techniques seem promising. RNA vaccines tend to be more effective in animal studies, but have also required innovations before use in humans. It may be time for gene-based vaccines.
Another benefit of gene-based vaccines is that manufacturers could probably produce large quantities much faster than traditional vaccines. DNA and RNA vaccines would also be more stable than conventional vaccines, since they do not use ingredients such as cellular components or chicken eggs. This would facilitate distribution, especially to rural areas.
Still a long way to go
The three gene-based vaccines and the other five candidates face many challenges before you or I are vaccinated. The fact that they are in Phase 1 and 2 trials is encouraging, but the goal of clinical trials is to reveal any problems with a candidate vaccine.
And there are many potential problems. Preclinical results in laboratory animals may not translate well to humans. The level of immune protection may be low. And people can react negatively when injected with the vaccine.
Any coronavirus vaccine could also produce a dangerous reaction called immune enhancement, where the vaccine actually worsens the symptoms of a coronavirus infection. This is rare, but it has happened with previous vaccine candidates for dengue and other viruses.
So how long before you have a COVID-19 virus vaccine?
There are no vaccines that have passed the Phase 1 or Phase 2 trials, and the Phase 3 trials generally take between one and four years. If the researchers are lucky and one of these first vaccines is safe and effective, we still have at least a year to find out. At that point, manufacturers would have to start producing and distributing the vaccine on a large scale.
It is unclear what percentage of the population would need to be vaccinated against SARS-CoV-2, but overall, 80% to 95% of the population must immunize to have effective immunity in the herd. Depending on what the virus does in the coming months, that may not be necessary, but if it is, there are 260-300 million people in the US alone. USA
Researchers are doing their best to develop a vaccine as quickly as possible while ensuring that it is effective and safe. Manufacturers can help by preparing flexible systems that can be ready to produce any candidate who crosses the finish line first.
If all goes well, Fauci’s 12-18 month prediction may be correct. If so, it will be thanks to the tireless work of scientists, the support of international organizations and manufacturers, all innovating and working together to combat this virus.
Marcos E. García-Ojeda, professor of molecular and cellular biology, University of California, Merced
This article is republished from The Conversation under a Creative Commons license. Read the original article.
This story is part of our special report titled “COVID-19 And You”. Do you want to read more? Here is the complete list.
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