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Since November 9, four manufacturers have announced the effectiveness of their vaccine: the German-American Pfizer / BioNTech alliance, the American Modern Laboratory, the British AstraZeneca / University of Oxford alliance and the Russians from the state-owned Gamaleia Institute. These data were only disclosed in press releases, without a detailed scientific publication. Cecil Czerkinsky, director of Inserm research, provides an update on these vaccines and the problems surrounding them.
The vaccination campaign is expected to start in late December-early January, isn’t that a bit too fast?
There is no need to worry at this point. The procedures for evaluating new Covid-19 vaccines are the same as for more traditional vaccines. Each year, for seasonal influenza vaccines, for example, laboratories perform safety and immunogenicity (immunizing power) tests in a few weeks on a few hundred individuals. Covid messenger RNA vaccines have performed these tests on approximately 30-40,000 people.
Messenger RNA vaccines are a new technology. Do we have enough perspective on their potential side effects on humans?
This technology has existed for 15 years in the laboratory, but its transition from the laboratory to the industrial phase is very recent. And Covid vaccines are the first application of this technology to humans. Their safety has been measured for four to five months and the short and medium term results are good. For most vaccines, 90% of side effects appear within 40 days of injection. This is why health authorities require laboratories to monitor patients for 60 days.
In the long run, it is still too early to measure the effects. This will be an important aspect of phase 4, the distribution of the vaccine in the population, with increased monitoring of pharmacovigilance to report any side effects.
What are the side effects of this new technology?
We still don’t have enough hindsight to determine them precisely. It will therefore be very important to have a follow-up of vaccinations, with the reporting of any serious effects to the pharmaceutical agency and to the health authorities to determine a causal relationship of the vaccination with possible serious side effects, albeit very rare.
Most of the side effects – which are, let’s remember, very rare – are allergies, inflammation at the injection site, headache, nausea and more rarely joint pain …
What is messenger RNA
The vaccines developed by Pfizer and Moderna, which appear to be the most advanced, use ultra-innovative technology. It involves injecting strands of genetic instructions called messenger RNA into our cells to make them produce specific proteins or “antigens” of the coronavirus. These harmless proteins will be released from our cells and delivered to the immune system, which will produce antibodies.
At no time the Sars-CoV-2 virus, not even inactivated, injected and RNA cannot integrate into our genome. The advantage with this method: it is not necessary to grow a pathogen in the laboratory, it is the organism that does the work. It is for this reason that these vaccines develop faster.
Since RNA technology is based on genetic modification within our cells, isn’t it likely to induce other side effects?
It’s possible. Diligent pharmacovigilance will allow us to learn more in the long run. But again, you don’t need to be particularly worried at this point. Messenger RNA consists of sending a coded message to the body so that it translates and stimulates a defense against the coronavirus. Basically, it is ultimately not that different from the more classic adenovirus technique which infects a cell in a way that translates the information provided by the virus and sets up an immune response.
What are the procedures for ensuring the safety of a vaccine during its development phase?
Three stages mark the clinical development process of a drug such as a vaccine. Phase 1 ensures its safety, i.e. it is well tolerated by a number of healthy adult individuals. Phase 2 enlarges the sample and ensures both product safety and the biological response it induces. Finally, phase 3 has the same objectives, on a larger scale (depending on the prevalence of infection in a region and / or in a given social group of healthy adult volunteers, including or not elderly volunteers and / or from a subpopulation. of people at risk) and statistically analyzing the clinical efficacy of the vaccine.
In the case of Covid vaccines, the three phases overlapped to accelerate development, for example by including phase 1 patients in later phases.
The health authorities then analyze the data and, if the product is well tolerated and effective, issue a marketing authorization, which allows the vaccine to be spread.
When the population begins to be vaccinated, it enters phase 4. It consists of monitoring all vaccinated people to identify any problems with vaccination in real conditions, in the general population.
In France, the Covid-19 vaccine will not be mandatory
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Laboratories promise 90% or even 95% efficiency …
This information is provided by the press releases of these pharmaceutical companies. We must therefore beware of these announcements for the time being. And, when all the data is available, narrow it down. In general, the people participating in clinical trials are young and healthy adults. And although people over 65 are included in the tests, they are also in good health, to avoid the risks.
Now that the vaccine is distributed to a priority audience such as exposed caregivers and vulnerable people, we will have more information on vaccine-induced immunity. We will know what vaccination allows in real conditions (with caregivers, who are mostly young) and in special conditions (with elderly and frail people with medical care).
How long and from what does the vaccine protect?
Another unknown factor concerns the nature of the induced protection. Vaccines in the final stages of evaluation appear to protect against disease, but we do not know if and to what extent they protect against transmission of infection. And if so, for how long.
We still have no information on how long the vaccine’s protection will be effective. In a context of unprecedented development speed, protection for 6 months would already be great news but a new logistical challenge if it were necessary to distribute or redistribute vaccination regularly! In the long run, we will find out more at the end of 2021.
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