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WWhen will we have a Covid-19 vaccine? Public-facing scientists such as the UK’s chief scientific adviser, Sir Patrick Vallance, and his American counterpart, Anthony Fauci, continue to repeat that it will not be before 12 to 18 months. But other voices, including some of the people in the race to create a vaccine themselves, have suggested that it could be as early as June. Who is right?
The first, probably, but it is complicated because this pandemic is forcing change in almost every step of the process by which a new vaccine reaches a needle near us.
“It really depends on what you mean by ‘having a vaccine,'” says Marian Wentworth, president and CEO of Management Sciences for Health, a Massachusetts-based global nonprofit that seeks to build resilient health systems, and a longtime observer of vaccine development. “If you mean one that can be used in a mass vaccination campaign, that allows us to get on with our lives, then 12 to 18 months is probably correct.”
But in terms of an experimental vaccine that is considered safe and effective enough to be implemented in a more limited way, for example, to high-risk groups, such as health workers, that could be ready in weeks or months, under the emergency rules developed by drug regulatory agencies and the World Health Organization in the context of the recent Ebola epidemics in Africa.
When Adrian Hill of Oxford University told the Guardian that his group’s Covid-19 vaccine candidate might be ready for the summer, he was probably referring to this type of preparation. Since then, the group, led by Sarah Gilbert, has stated that a vaccine that has been shown to be effective in phase 3 clinical trials that could be manufactured in large quantities will not be ready before fall, even in the best case scenario. And that scenario is “highly ambitious and subject to change.”
Typically, a vaccine is developed in the laboratory before being tested on animals. If it is safe and generates a promising immune response in this preclinical phase, it enters human or clinical trials. These are divided into three phases, each of which takes more time and involves more people than the last. Phase 1 establishes the safety of the vaccine in a small group of healthy individuals, with the goal of ruling out debilitating side effects. Phases 2 and 3 prove efficacy, and in an outbreak like the present one they are carried out in places where the disease is prevalent. Parallel to these later phases, the production capacity of the candidate vaccine is gradually developed, so that factories are able to produce it on a large scale as long as the regulatory agencies judge that it must be licensed.
In an article published in The New England Journal of Medicine On March 30, representatives of the Oslo-based non-profit Coalition for Innovations in Epidemic Preparedness (EpiP), which is helping to finance and coordinate the development of the Covid-19 vaccine, presented an accelerated version of this process. that they think is best suited for a pandemic. This “pandemic paradigm” implements certain steps in parallel, such as phase 1 animal clinical testing. It also involves increasing production capacity before sufficient safety and efficacy data are available, a financially risky step, as that may not never materialize, and one that requires governments and nonprofits like Cepi to share that additional financial risk with pharmaceutical companies if they want them to participate. Mass production is critical in a pandemic, when hundreds of millions, if not billions, of doses are needed, and many countries are now struggling to build new vaccine production facilities.
“People now appreciate that the lengthy conventional vaccine licensing process will not be helpful in the context of an epidemic,” says Beate Kampmann, who runs the vaccine center at the London School of Hygiene and Tropical Medicine.
Cepi prudently did not attach a timeline to its accelerated paradigm, but the 12 to 18 month estimate already takes that into account. Bringing a new vaccine to the clinic has taken 10-20 years in the past. However, the accelerated paradigm is now being implemented. Moderna, a Boston-based biotechnology company, saw its experimental Covid-19 vaccine enter human trials on March 16, just 10 weeks after the first genetic sequences of Sars-CoV-2, the virus that were released, were released. causes disease. Others will follow soon.
“We are reaching the candidates much faster,” says Kampmann, who attributes this progress to the progress made in the fight against Ebola. “The advancement in technology that we’ve seen in the last five years has really made a difference.”
However, there are many obstacles ahead. Most of the 50 Covid-19 vaccine candidates being developed and tested will not make it to the licensing stage, and those who have exited the blocks faster may still encounter problems later. Moderna’s innovative technology enabled it to rapidly generate a candidate, but no vaccine using this platform has been licensed to date.
On the other hand, at the Pasteur Institute in Paris, a candidate for the Covid-19 vaccine is still in preclinical development, but due to taking advantage of established technology, a licensed measles vaccine, the testing and licensing processes will be more rapid. And this type of vaccine can already be produced in large quantities.
While there can be no shortcuts to establishing safety and efficacy, proposals have been made for how these experimental vaccines could be tested more quickly without sacrificing scientific rigor. In February, for example, the WHO published a draft protocol for phase 2 and 3 trials that would evaluate multiple candidates simultaneously, in trials from several countries according to standardized criteria.
Another proposal is to conduct controlled challenge trials in humans, in which healthy volunteers receive a candidate vaccine and then become infected with Sars-CoV-2. These are ethically questionable, especially before scientists understand why young, healthy people end up with fans. A similar approach, implemented by London-based clinical research group Hvivo, invites volunteers to become infected with a milder coronavirus, but it is unclear how applicable their findings will be to Sars-CoV-2.
There are still many unknowns regarding Covid-19, including how long any vaccine will provide protection. A strong indication of this will be whether people who have recovered from the disease can get it again. There have been anecdotal reports of reinfection, but the phenomenon is not well understood. “If our own body can’t stop us from having it again, that would be a pretty damning sign,” says Wentworth.
Once a vaccine is licensed, there will still be political obstacles to getting it where it is needed, because each country or public health jurisdiction has to make its own decision to implement it. There will also be prioritization issues, who should get it first, if supplies are limited, which authorities are now discussing.
A vaccine approved within a year may come after the end of the current pandemic, but if so, it won’t go to waste, first because Covid-19 may reappear seasonally, and second because the vaccine could be reused in the event of a coronavirus outbreak. different. That will not be a consolation for the victims of this pandemic, nor for their families, but it does mean that humanity will be better protected in the future. As Wentworth says: “That learning, we will not unlearn.”
