Vaccines are the most carefully controlled medicinal products on the market. But how can you be sure that they work and are safe? The microbiologist and virologist, Dr. hab. n. med. Tomasz Dzieciatkowski.
- Dr. Dzieśctkowski: vaccines are rigorously and very carefully tested. It happens that the fourth phase of research is abandoned in the case of drugs, although rarely, and it is necessary in the case of vaccines
- Work on a vaccine starts with an idea of how it would work. When the preparation is formed, the so-called preclinical tests on cells and animals
- The next step is human clinical trials carried out in three phases. Adults and healthy people are selected from among the volunteers. Why healthy? – The point is not to have any additional factor that could affect the results – explains Dzieiątkowski
- – If the tests are successful and nothing happened along the way, the vaccine is registered and it enters the market. This is where the fourth phase research begins. It occurs during normal use of the vaccine and affects tens or even hundreds of thousands of people. It lasts until the vaccine is replaced by another, more effective one, says the expert
- Dr. Tomasz Dzieiątkowski: Unfortunately, I do not believe that the COVID-19 vaccine will be available in 2020, although I would very much like it. In a very optimistic scenario, it may appear in the first quarter of next year
Monika Mikołajska / Medonet: Why are vaccines the most closely controlled medicinal products on the market?
Dr hab. n. med. Tomasz Dzieciatkowski: They actually get rigorously and very carefully tested. It happens that the fourth phase of research is abandoned in the case of drugs, although rarely, and it is necessary in the case of vaccines. This means that monitoring of a particular vaccine will not stop until a different vaccine is invented that is more effective than it. We should remember that vaccines in most cases come from biological creations (e.g. they contain inactivated pathogens) and their constant observation is an absolute condition here.
What happens from the beginning of vaccine development until it is available to us?
It all starts with the idea of how such a vaccine would work. If this stage is behind us and the physical preparation exists, the so-called preclinical tests.
First, in cell cultures, it is tested whether the product is toxic to the cells. So it is checked whether it does not cause the so-called cytotoxic effect and that there are no other undesirable reactions taking place in the cells. If all is well at this stage, animal testing begins.
Unfortunately…
Yes, because cell lines in this case cannot reflect the complexity of the entire living organism. These tests are used, inter alia, mice, rabbits, cats. The model animal for SARS-CoV-2 research is the ferret.
What is animal testing for vaccines?
They inject him with the preparation, checking if the animal does not die after its administration or if there are other disturbances in its physiology. There is no specific duration for preclinical testing. Several independent repetitions of the study have to be carried out and the effects compared.
If the results are successful, human trials begin. Who can take part in them?
Adults and healthy people are selected from among the volunteers. Recruitment for tests is announced earlier, and participation in them is usually paid. Recruited people are given different doses of the test preparation and the effects are observed.
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Why do participants need to be healthy?
This is a frequent accusation by people who oppose vaccines. Meanwhile, the point is not to have any additional factor that could affect the results. If in the experiment we have, for example, a lot of people with diabetes and side effects appear, we will not know if they are related to the tested vaccine or maybe to the coexisting disease.
Human clinical trials essentially consist of three phases. What is happening in each of them?
The first phase of the tests lasts a minimum of three months, but may also last a year. Usually several dozen people take part in it. At this stage, different doses of the potential vaccine are administered and it is checked whether it is toxic to humans and what dose of it guarantees safety. On this basis, the best dose of the preparation is determined.
All this is done on an outpatient basis. Volunteers are not in the hospital (they would have to stay there for several or even several months!). They show up at medical check-ups and laboratory tests, e.g. every three weeks.
The second phase is similar, but here the tested group increases to several hundred people. It may last three months, six months, or even three years. A previously determined optimal dose of the vaccine is given to volunteers and it is checked whether the immune system is responding to it and how long the immune response lasts.
The third phase already includes several thousand healthy people. Importantly, research is usually conducted where the risk of a given pathogen is high. In the case of COVID-19, it is, for example, Great Britain, the USA, Brazil and India. Volunteers are given specific doses of the vaccine – one or two, and they check the immune response for side effects. Such results can be compared with the control group, i.e. those who were not given the vaccine. This phase lasts from about half a year to three years under normal conditions.
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What happens if there are problems – e.g. any side effects? An example is a vaccine developed by AstraZeneca. In June, WHO recognized it as the leading project in the world. The third phase of testing has recently started, but has been put on hold. The reason was the symptoms observed in one of the test persons. What does this mean for the future of the vaccine?
Since side effects appeared in one person tested, it is necessary to find out whether they were really related to the vaccine – because that does not necessarily have to be the case. Until a causal relationship has been found or ruled out, testing cannot continue.
For now, it is not known whether the research will resume and whether the work on the vaccine will be completed …
At the moment, work has been suspended until clarification. It is as if we were driving a car in a snake and we were stopped by a policeman. He found our driving style suspicious, so he checks what caused it. It may be that we were avoiding the herd of hedgehogs, it may also be that we are on “double throttle” or the road is simply too full of holes. It is the duty of the policeman to find out why we were driving like this and take the appropriate steps. The same is true of the company that conducts research on the vaccine.
If it turns out that this was the case, clinical trials will continue. However, if they do find a link between an adverse symptom and the vaccine, they will need to follow up on the rest of the test participants. In the event that the link to the vaccine is proven in this one person, that case will be described and the research will continue.
What if the side effects also appear in others?
It depends. If in the group of 5 thousand one or more people develop these problems, it is necessary to consider whether the benefits of using the vaccine are greater / less than the risk of the observed side effects. If this symptom occurs too often, the vaccine will be withdrawn from clinical trials and will never be on the market. This was and is the case with the HIV vaccine, for example. Despite 40 years of work and intensive research, there is still no such preparation.
At this point, I would like to remind you that there was no, there is and will not be a medical preparation – a vaccine or a drug – that would be 100 percent. safe. Statistics say about it – something can always happen.
After a successful third phase of testing, is the vaccine approved for use?
If the tests are successful and nothing happened along the way, the vaccine is registered. The organization responsible for authorizing medicinal products, i.e. in the case of the EU, the European Medicines Agency (EMA), collects results from all centers and summarizes (what is the immune response, what dose, what side effects may occur, what percentage of people e.t.c). After the registration is completed, the preparation is admitted to the market.
Does this mean that such a vaccine is no longer being tested?
Exactly no – that’s when phase four trials begin. This is not a medical experiment and nobody is paid for anything anymore. This phase of research takes place during normal vaccine use and affects tens or even hundreds of thousands of people. The point here is whether, due to certain genetic predispositions, the preparation works worse – for example, would people with blue eyes react worse to the preparation than people who have brown eyes. Based on the observations, the registration of the preparation is extended with the latest findings.
This fourth phase continues until the vaccine is replaced by another, more effective one. It can therefore be said that vaccines are tested from design until they are replaced by a different, more effective formulation.
Is every country required to follow these research stages? Does everyone set their own standards for drug and vaccine testing?
USA, EU countries, Canada, Great Britain, Japan – they have their own standards, but they follow established rules. Generally, however, full disclosure is required and everyone can see what the individual phases of clinical trials of a given preparation look like, who finances the research, who is included in the study group, etc.
The Chinese have their own rules, although they are currently trying very hard to make them as close to Western standards as possible. However, there are also countries which follow their own laws and generally do not keep their tests openly.
An example of full disclosure is the position of AstraZeneca, which openly announced that it was suspending the research because side effects occurred.
Yes. Of course, this accident could be exploited by anti-vaccine movements. But the situation should be treated quite differently: yes, something similar happened, everyone knows about it and is going to clarify the situation. This approach makes the preparations safe (although they will never be 100%, because they cannot be).
However, it should be emphasized that in the current situation we should talk about an adverse event rather than an adverse reaction. This is because there is no precise link between the vaccination and the symptoms observed.
So it takes years to test a vaccine. Now, in the era of a pandemic, can this process be accelerated without risking the safety of the preparation?
Work on the HPV vaccine took 17 years! Indeed, however, in difficult times such as the current pandemic, individual phases of clinical trials may be shortened, but not be omitted. This shortening is also specified, it cannot be done arbitrarily, you have to keep these minimum test periods – we talked about it above.
Do you think we have a chance for a COVID-19 vaccine later this year?
I would like it for you and myself, but unfortunately I do not believe that it will be available in 2020. In a very optimistic scenario, it may appear in the first quarter of next year. However, it will probably be mid-2021.
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