SScientists around the world are competing to develop a coronavirus vaccine, and many believe that at least one could be launched early next year. According to the World Health Organization, about 23 vaccines are under clinical evaluation, and more than 130 are in development.
The Modern biotechnology firm and the National Institutes of Health said their vaccine elicited a desired immune response in 45 individuals; it will go on to larger scale tests later this month. The University of Oxford, which has partnered with drug maker AstraZeneca to create another vaccine, said it anticipated “positive news” in early trials of its drug.
The mumps vaccine, widely considered the fastest ever developed, took four years. Experts explain what it takes to develop a vaccine and what comes next.
How optimistic are you that we will have a vaccine in early 2021?
Angela Rasmussen: I am optimistic. It won’t necessarily be the perfect shot. We could find early evidence that some of these vaccines are at least partially effective, and that’s enough for now because the need is so great.
Anna Durbin: I think we are going to [understand] the effectiveness for one or perhaps two candidates by the end of 2020 at the beginning of 2021 at the rate things are going. I am more concerned with the ability to produce enough for everyone who needs it.
Why is a vaccine that is only partially effective considered a success?
Rasmussen: Although it may not provide sterilizing immunity, which is the ability to completely prevent infection, it can provide protection against serious illness.
Studies with the Oxford Covid-19 vaccine suggested that it prevented the formation of the disease in the lungs of the monkeys who were vaccinated. In that sense, a vaccine that is partially effective may not be able to prevent transmission or infection, but if it reduces the severity of the disease, it is still a public health benefit.
Can you describe the steps that are required to create a vaccine?
Rasmussen: Phase one trials only seek safety. You are giving the vaccine to a smaller group of patients to make sure that the vaccine does not have any negative side effects.
A phase two test generally tests a combination of safety and efficacy. A phase three test is like a phase two test, except that it is with many people. In this case, we went directly from phase one to phase two and three combined tests.
Durbin: Usually the minimum amount of time since [identify] A pathogen to go through phase three is approximately 10 years old, and can take much, much longer. The first time we really saw compression of that timeline was with the 2014-2016 Ebola outbreak in West Africa. After that, we realized that we need to have vaccines or vaccine platforms ready to go when a new pathogen comes out.
What are the risks of speeding up vaccine trials?
Rasmussen: You lose the ability to conduct a full and complete phase three clinical trial. You have to wait for people to be exposed to the virus and as if they weren’t necessarily immediately exposed. Another thing about many vaccine trials is that part of the intention is to see how long the antibodies last, and there is no way to speed up that process.
It’s really good that multiple candidate vaccines are being developed because even if we have some kind of vaccine in early 2021, it might not be the most ideal vaccine to provide long-term immune protection.
They are studies of human challenge – studies that deliberately expose subjects to the virus – an effective way to speed up the vaccine development process?
Rasmussen: Human challenge trials are a bad idea for a couple of reasons. First, patients cannot give their informed consent to participate in a trial like that, because there are many things that we do not yet know about this virus.
Two, people have suggested that the way to safely perform a human challenge test is to restrict it to the lowest-risk group of people: probably young women with no known pre-existing medical conditions. The amount of information you can get from a test like that is very limited. You are not [learning] how that vaccine might work in older people, men, or people with pre-existing conditions.
We are seeing reports that the level of antibodies in people who have been infected with the coronavirus decreases over time. What does that mean for a vaccine?
Durbin: After getting infected, the cells in your body make antibodies. When the virus disappears, those cells decrease in number, but it has a memory response. We call that the anamnestic response. I’m not necessarily relying on the amount of antibodies in my blood, but on my body being able to recognize the pathogen and mount a response very quickly.
Rasmussen: We may need a booster for any type of vaccine, and that is not uncommon. Many vaccines do not provide protection for life.
How fast can a new vaccine be implemented?
Rasmussen: Many investments have been made so that large-scale manufacturing can begin as soon as a vaccine is developed. But all the preparation in the world is not going to do large-scale manufacturing [happen] overnight.
The first vaccine will likely be launched as a priority, and that will be a subject of much debate and controversy. I imagine that healthcare workers and essential employees will be among the first to obtain it.
Much will depend on the type of vaccine. Modern vaccine, for example, is very easy to manufacture, but the challenge is that it must be kept very cold. So a vaccine like that might be easy to make, but it’s not that easy to distribute.
Durbin: The good news is [drug companies] are starting to manufacture at risk [before they are approved]. So they are making doses now and working to expand that capacity.
There are other regulatory and administrative things, whether it is authorized with emergency authorization or fully granted [Food and Drug Administration] license – and distribution logistics is complicated. It would take months, at a minimum, to even use the first hundred million doses that are made.
Do you fear that once developed, many Americans will choose not to get vaccinated?
Durbin: That is a problem. That is why we have measles outbreaks in communities that do not vaccinate. We are going to have to do a much better job to help [people] I understand that you are not only protecting yourself, you are protecting someone’s grandmother.
Rasmussen:
There are other people who [think] we are going to get the vaccine and it will solve everything and things will return to normal the next day. And that is not the case either.
That being said, I will definitely take the vaccine as soon as it is available.
Experts:
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Angela Rasmussen, virologist and research scientist associate, Columbia University Mailman School of Public Health
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Anna Durbin Johns Hopkins Bloomberg School of Public Health physician and professor of international health
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