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The race to create vaccines for the novel coronavirus is entering a critical phase, with several candidates who were the first to walk out the door starting to release late-stage trial data and possibly seeking early regulatory approval. Several “winners” are likely to arrive in the market, and success will depend on a number of factors reflected in this tracker.
Historical
Vaccines that do not demonstrate overall safety in the small phase 1 and 2 trials will not go further. Some of the major coronavirus candidates have the advantage of being based on familiar and time-tested formulas, including candidates containing viral protein or inactivated whole virus, with or without an immune-stimulating adjuvant. Other contenders represent newer technologies, including those based on RNA, DNA, or virus-like particles, but even some of these approaches have already led to licensed vaccines against other diseases or at least. have undergone previous human trials. And they have a few advantages of their own, like fast manufacturing or lower dose requirements.
Viral vectors are both old and new, having long been in development for other applications and already used in some licensed vaccines. This design reliably elicits an immune response, but vaccines may also share a potential problem: Harmless viruses that serve as a “vector” to carry genetic instructions into cells may already be recognized by the human immune system, which may reduce the effectiveness of the vaccine and require higher doses. Another concern is that a first injection of the vaccine could create immunity to the vector which weakens the effect of a second injection. For vaccine developers, “it’s a risk that needs to be mitigated,” Nathalie Boy, CEO and CSO of BIOASTER and former head of the Global Adjuvant Center for Vaccines at GSK Biologicals, told Reuters. Large-scale trials will reveal if the risk is serious and if vaccine designers can find a way around it.
Test results
Whether a pandemic vaccine requires one or two doses and the distance at which the injections must be administered can impact how convenient it will be to distribute and how much it costs. Phase 3 trials – which typically include tens of thousands of volunteers with a greater diversity of backgrounds and a larger age range than early safety trials – will also reveal how effective a vaccine is: how much of the population it is likely to protect and to what extent.
The race for a SARS-CoV-2 vaccine challenges the vaccine industry at all levels, Boy said. Vaccine designers aren’t just trying to make a single vaccine to protect 2 billion or more people, they’ve done it without knowing what immune responses equate to protection against this new virus. As a guide, many have compared the responses of volunteers from the first trials to those seen in recovered COVID-19 patients. In phase 3, researchers can begin to see who is resistant to infection in the real world. Experts predict that the main candidates could protect around 70% of those vaccinated against infection or against severe COVID-19 if they are infected. The US FDA has set a minimum threshold of 50% efficacy to even consider a vaccine for approval. It is still unclear how long this protection will last, but it could be as little as a year, AstraZeneca CEO Pascal Soriot said last June and BioNTech CEO Ugur Sahin said. echo in November.
Advance orders
All the unknowns have not stopped governments and international organizations, including the WHO, through its COVAX initiative from disbursing funds to a handful of applicants to accelerate their development and regulatory review. Fierce international competition to lock in billions of dollars in purchase commitments has also been going on for months, and some companies will soon start delivering millions of doses.
Now, vaccine candidates must prove themselves. We’re tracking the candidates closest to delivering results and a few that represent promising new technologies to watch.
Sources
Reuters reports, companies, Vaccine Center of the London School of Hygiene and Tropical Medicine, WHO
Reporting and writing by Christine Soares
Graphics, design and development by Travis Hartman
Illustrations by Ally Levine
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