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Moderna’s vaccine is the second recommended for emergency use authorization in the United States.Credit: Paul Hennessy / NurPhoto / Getty
A week after US regulators authorized the country’s first coronavirus vaccine, a panel of outside advisers voted in favor of a second: another RNA vaccine, made by Moderna of Cambridge, Massachusetts.
The December 17 vote, which was unanimous with one abstention, is widely seen as a final hurdle for Moderna’s vaccine, and the U.S. Food and Drug Administration (FDA) is expected to grant it a use authorization. of emergency. A week earlier, the agency licensed a similar vaccine made by Pfizer of New York City and BioNTech of Mainz, Germany, about a week after UK regulatory authorities did the same.
The speed of these clearances reflects the urgency of the pandemic and is a testament to the scientific advances that made rapid vaccine development possible, immunologist James Hildreth, president of Meharry Medical College in Nashville, Tennessee, said at the panel meeting on Thursday. “Going from having one virus sequence in January to having two vaccines available in December is a remarkable achievement.”
The authorization will be the first for Moderna, a ten-year-old biotech company that had long been committed to revolutionizing medicine by harnessing RNA as a therapeutic agent, but had yet to bring a drug or vaccine to the clinic. It will join a growing list of organizations with coronavirus vaccines that are rolling out around the world, including teams in China and Russia.
In the United States, vaccines offer a ray of hope amid the prospect of a harsh winter. The country is recording thousands of deaths from COVID-19 every day, and it is expected to increase during the winter holiday season. Coronavirus infections are so rampant that Moderna was able to hit the primary goal of its trial five months earlier than expected, said Jacqueline Miller, the company’s senior vice president and director of infectious diseases.
RNA vaccine
The Moderna vaccine, which was developed in collaboration with the US National Institute of Allergy and Infectious Diseases, works in the same way as that produced by Pfizer and BioNTech. Both consist of RNA molecules encased in lipid nanoparticles. The RNA from both vaccines encodes a slightly modified form of the SARS-CoV-2 protein known as a spike, which allows the virus to infect human cells.
Once taken up by cells, the RNA is used to make the protein, which then triggers an immune response. RNA does not enter the nucleus where the cell’s genome resides and is degraded by the cell within one day of injection.
Like Pfizer’s vaccine, Moderna’s seems to be very effective (about 94%) in preventing symptomatic SARS-CoV-2 infections. Its safety profile is also similar to that of Pfizer, with fatigue, headaches and pain at the injection site among the most cited side effects.
Since the Pfizer vaccine was released in the UK and the US, there have been occasional reports of recipients experiencing severe allergic reactions called anaphylaxis after injection. So far, there have been no signs of such reactions in Moderna’s trial, which excluded people who have had anaphylactic reactions to previous vaccines, but not those with other allergies, such as reactions to food.
The two vaccines differ in the composition of the lipid nanoparticle that encloses the RNA, and Moderna’s formulation allows the vaccine to be stored at a higher temperature than Pfizer’s, which must be kept at -70 ° C, much colder than a normal freezer. Moderna vaccine can be stored in a -20 ° C freezer for 6 months and in a refrigerator (approximately 4 ° C) for 30 days. This promises to streamline the logistics of vaccine implementation, particularly in rural areas and in countries with limited health care infrastructure.
Continuous trials
FDA advisers spent much of the December 17 committee meeting discussing when and how to offer a vaccine to participants in the placebo arm of Moderna’s trial after an emergency use authorization is granted. Once a coronavirus vaccine is available, participants can choose to drop out of the trial to ensure they can receive a vaccine. Maintaining the integrity of clinical trials after vaccine authorization, to collect data on long-term safety and duration of protection, is an imminent challenge for developers.
Last week, Pfizer proposed that when its participants are eligible to receive a vaccine as part of a national rollout, the study researchers will tell them whether they received the vaccine or a placebo. Moderna, instead, has proposed to ‘unmask’ the whole trial at once after receiving an emergency use authorization, informing all its participants what treatment they have received and offering to vaccinate those in the placebo group with doses that had already been reserved. for the clinical trial.
Some FDA advisers cautioned that this approach would sacrifice valuable weeks of data collection and allow some participants to receive the vaccine earlier than others in similar priority groups in their communities. Others argued that while the approach is not ideal, it might be necessary given the complexity of vaccine deployment in the United States, where individual state and local governments will set their own priorities. “It’s a hodgepodge here, it’s not practical,” said biostatistician Jeannette Lee of the University of Arkansas for Medical Sciences in Little Rock.
Offering the vaccine to trial participants could help the company keep them enrolled in the study, so it can continue to collect data on safety and immunity, said Lindsey Baden, an infectious disease specialist at Brigham and Women’s Hospital in Boston, Massachusetts. who was asked by Moderna to speak to the committee about it. Some healthcare workers who participated in the trial were already leaving to get the Pfizer vaccine, he said. “If we lose our volunteers, the opportunity to learn something else will be substantially affected,” he said. “We have to be practical.”
