07/28/2020 - 14:54
- Clarín.com
- World
The search for a vaccine against the coronavirus at a speed unprecedented in the context of a global competition with huge financial interests involved. But it will be necessary to be careful before probable later discarded announcements and frustrated hopes.
In its latest report, on July 24, the WHO lists 25 "vaccine candidates" tested in human clinical trials (there were only 11 in mid-June).
Most of these tests are still in phase 1 (assessing their safety), and others in phase 2, in which their efficacy is already being explored.
But only four vaccine candidates are in the most advanced stage, phase 3 , in which efficacy is measured on a large scale.
The modern American company began this phase on Monday, during which 30,000 volunteers will be tested.
In mid-July, two Chinese projects also entered phase 3: that of the Sinopharm laboratory, tested in the United Arab Emirates on 15,000 volunteers , and that of the Sinovac laboratory, tested with 9,000 health professionals in Brazil, in association with the local research institute. from Butantan.
The fourth phase 3 project is European, developed by the University of Oxford in cooperation with the company AstraZeneca, and is being tested in the United Kingdom, Brazil and South Africa.
In addition to the tests already started, the WHO has counted 139 candidate vaccine projects, still in pre-clinical development phase.
There are different approaches. Some teams work on conventional vaccines, which use a deactivated virus, such as those from Sinovac and Sinopharm.
There are also "subunit" vaccines, based on proteins (antigens), that trigger a virus-free immune response.
The so-called "viral vector" are more innovative : another virus is used as a support, which is transformed and adapted to fight covid-19. This is the technique chosen by the University of Oxford , which uses an adenovirus (a very common family) from chimpanzees.
Finally, other innovative projects rely on "DNA" or "RNA" vaccines, experimental products with pieces of modified genetic material. This is the case of the Modern company.
"The more candidates there are, and especially the more different types of vaccine candidates there are, the more possibilities we have to achieve something," explains Daniel Floret, vice president of the Technical Commission on Vaccines, under the authority of the High Health Authority (AFP) HAS) French.
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The preliminary results of two candidates, one from Oxford University and one from a Chinese company, CanSino, were published on July 20 in the medical journal The Lancet .
Both are considered encouraging. They show that they elicit "a strong immune response , " triggering the production of antibodies and T lymphocytes (specialized cells of the immune system).
Furthermore, they have been well tolerated by patients since no serious side effects were recorded. The most common were headache, fever, fatigue, and pain at the injection site.
However, it is still too early to draw conclusions.
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Watch the special"We do not yet know whether these levels of immunity can protect against infection (...) or whether it is capable of protecting in the most fragile cases of covid-19," said Jonathan Ball, professor of molecular virology at the University of Nottingham ( United Kingdom), who did not participate in these investigations.
In addition, a well-known British study in mid-July suggests that antibody-based immunity could disappear in a few months , which could complicate the development of an effective long-term vaccine.
In all parts of the world, procedures have been accelerated in an unprecedented way. This is particularly tangible in China, a country that has seen the SARS-CoV-2 virus emerge.
Fundraising has been launched by nations and foundations. Unlike Europe, the United States is doing it on its own.
The Trump administration seeks to accelerate the development of a vaccine, especially for the 300 million Americans, for which it launched Operation Warp Speed, a name taken from the science fiction series Star Trek that identifies faster travel systems than The speed of light.
For this, Washington has bet on several horses at the same time and has invested billions of dollars in different programs.
This rampant career has even acquired the profile of a spy novel. The United Kingdom, the United States and Canada have accused Russian intelligence services of being behind attacks by computer hackers to steal research data on a vaccine. And, in the United States, two Chinese were accused on similar grounds.
Both Moscow and Beijing reject these allegations.
"To authorize a covid-19 vaccine, clinical trials must provide a high level of safety, efficacy and quality, " said the European Medicines Agency (EMA).
For the vice president of the French vaccination commission, "one of the key points is to show that the vaccine is not likely to cause an exacerbation of the disease," that is, to become more serious.
It happened in monkeys "during attempts to develop vaccines against MERS-CoV and SARS", two other coronaviruses, recalls Daniel Floret.
In humans, this phenomenon was found in the 1960s with certain measles vaccines.
The EMA believes that "it could take at least until early 2021 for a covid-19 vaccine to be ready for approval and available in sufficient quantities."
But, the most optimistic, starting with certain pharmaceutical companies, assure that it is possible to achieve it in the last quarter of the year.
"I am not sure if it is a realistic thing to say that we will have a vaccine for the fall (boreal), it is necessary to moderate this enthusiasm," estimates Floret.
If it were available in early 2012 "it would already be a great miracle" , since it usually takes several years.
And, in the worst case, you may also never be able to develop a vaccine.
Even if the researchers are successful, another question remains: Will people accept being vaccinated, in a context of growing distrust of vaccination?
"As the frequent measles epidemics demonstrate, we have not been good at responding to people's concerns about vaccines. And, if we do not learn from these mistakes, any coronavirus vaccination program would be condemned beforehand," the pediatrician warned. American Phoebe Danziger, in a recent article published in the New York Times.
Source: AFP