Pharmaceutical companies are updating vaccines and testing them on the population with the goal of being ready to quickly update the drug should a resistant strain emerge. The crux of clinical tests
How are current vaccine manufacturers moving to address the possibility of a new coronavirus mutation emerging that could escape the vaccine-induced immune response? The variants currently in circulation, especially the now dominant Delta in the world, are more contagious, but not different enough to put current vaccines at risk. However the evolution of the virus continues, we cannot rule out that the next generation pathogen may be less problematic for our immune system than the existing virus. Magazine Nature interviewed three major Covid vaccine manufacturers, Pfizer, Moderna and AstaZeneca to understand how they are preparing for this possible scenario.
Practice with the variations in circulation
In recent months, all three companies have been carrying out research by practicing on known variants of Sars-CoV-2 such as Beta and Delta; tested vaccines with up-to-date clinical trials and fine-tuned workflows to be ready to move quickly if and when a new immune escape variant really emerges. At some point, inevitably, we will have to produce variant vaccines if this is the way to maintain immunity in the population, but they have not yet gotten to the point where the necessary vaccine update says. Paul Bieniasz, a virologist at Rockefeller University in New York City. Practicing with existence variants seems like a reasonable approach.
First generation vaccines work
The first generation of Covid vaccines appears to provide high protection against Delta and other known variants, at least in the prevention of serious illness and hospitalization. Pfizer, Moderna and AstraZeneca say their vaccines, based on the original Sars-CoV-2 strain first detected in Wuhan, China, still offer the best protection against all known variants and at the moment, it should be remembered, there is no need. an updated ad hoc vaccine. But better be ready. If an immune escape variant were to emerge, mRNA vaccine manufacturers such as Pfizer or Moderna probably could design and synthesize the update in a few days. Viral-vector vaccines such as AstraZeneca could follow suit. Pfizer CEO, Albert Bourla, he said last June that if the need arises for a new vaccine against Covid-19 his company would be able to prepare it within 100 days.
To make an RNA vaccine, a genetic sequence is created, which is then encapsulated in a fatty substance. Viral vector vaccines are instead constructed by inserting the genetic sequence into a harmless carrier virus, which is cultured in a bioreactor and purified. Before these new vaccines can be distributed they will have to be tested on humans, and that takes time.
Pfizer-BioNTech are testing a specific vaccine against the Beta variant in a randomized, controlled clinical trial involving 930 participants. In August, the companies began testing a multivalent vaccine against Alpha and Delta. We are not carrying out these tests because we think we need them to combat these strains but to test all the steps necessary to update the vaccine: from pre-clinical research, to production, to clinical tests up to the presentation of the data to the regulatory bodies in order to be ready. and quick to leave when the need arises, he says Philip Dormitzer, vice president and chief scientific officer in Pfizer’s Viral Vaccine Development Department. A sort of dress rehearsal, then. So much so that the pharmaceutical company has stated that it does not intend to market the vaccines created against the Beta and Delta variants.
Moderna is recruiting 300-500 participants to test new vaccines against Beta and Delta and against the two variants together. The purpose – he says Jacqueline Miller, senior vice president and chief of infectious disease research at Moderna – establish a well-established path that may prove useful in the future on strains that may prove more resistant to vaccines. AstraZeneca has initiated a large study of a beta-specific viral vector vaccine. Launched in June, the studio stands enlisting more than 2,800 participants, many of which have already been vaccinated with a messenger RNA vaccine or AstraZeneca’s first-generation viral vector vaccine. We are practicing this vaccine, but we are also developing it and if successful it will be ready for use, says Mene Pangalos, executive vice president of biopharmaceutical research and development at AstraZeneca.
The effectiveness of vaccines in the real world
It will not be easy to determine the true efficacy of variant vaccines. It may be difficult to find volunteers who have not yet been vaccinated but are willing to experiment with a new one, especially in those areas of the world that have had access to mass vaccination. They also arise ethical problems in recruiting placebo groups for randomized controlled trials, since effective vaccines are available. An alternative to randomized controlled efficacy trials could be immunogenicity studies, as well as real-world efficacy research, he says. Matthew Hepburn special adviser to the White House Office of Science and Technology Policy. Immunogenicity studies would measure the immune responses triggered by variant vaccines (increased levels of antibodies or B cells) compared to first generation vaccines.
According to reports by Nature, this would be the direction in which some vaccine producers are moving: on the basis of the indications of the European regulatory bodies AstraZeneca will use this method for testing Beta vaccines. Moderna is also focusing on data of the immunogenicity and is collaborating with the hospital system in Southern California to collect real data on vaccine efficacy. In these observational studies, participants can choose whether or not to receive a vaccine, and researchers monitor the two groups to see how they fare. Of course they are not perfect studies because the two groups may have different behaviors and risk factors.
How to know when an updated vaccine will be needed
But how will public health authorities figure out if a variant escapes vaccine-induced immunity? In a practical way, if we were to see many vaccinated people hospitalized in serious condition, it would mean that something went wrong. The World Health Organization follows a very precise and well-established procedure for deciding when to update a flu vaccine to adapt it to an emerging strain. These are decisions based on a long history of monitoring the virus that does not exist for Covid. The hope that even with the anti Covid vaccines the updating procedure can become more streamlined, just like it happens for the flu vaccine.
October 22, 2021 (change October 22, 2021 | 11:34)
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