Following the preliminary success of a COVID-19 vaccine in the United States, another leading candidate for the vaccine is showing promise. Preliminary results indicate that Moderna’s coronavirus vaccine is nearly 95 percent effective in preventing disease, including severe cases of the disease, the biotech company announced on Nov. 16.
“This is a crucial moment in the development of our COVID-19 vaccine candidate,” Moderna CEO Stéphane Bancel said in a press release. The results are the "first clinical validation that our vaccine can prevent COVID-19 disease."
Just last week, global pharmaceutical company Pfizer and German biotechnology company BioNTech announced that their coronavirus vaccine is more than 90 percent effective in preventing people from getting sick from the virus (SN: 11/9/20). If both vaccines continue to work well in clinical trials, the United States could soon have two coronavirus vaccines available for those at higher risk.
Both Modern and Pfizer plan to file applications with the U.S. Food and Drug Administration in the coming weeks to allow emergency use of their vaccines.
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Moderna’s new findings are based on an analysis of 95 coronavirus cases that have occurred so far during the company’s phase III vaccine clinical trial. Researchers began counting who became ill at least two weeks after participants received a second dose of vaccine. Of the cases, 90 were in people who received a placebo and five in the vaccinated group, which made the vaccine effective at 94.5 percent. The data are preliminary and have not yet been reviewed by other scientists.
The FDA recommends that COVID-19 vaccines be at least 50 percent effective, meaning that a vaccine should reduce COVID-19 cases in vaccinated people compared to a placebo by half (SN: 10/4/20 ). Both Moderna and Pfizer clinical trials are ongoing, so the final efficacy of the vaccines could change.
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It is unclear how well the Modern vaccine performed in different ages or racial groups, although the results include some older participants and people from different racial backgrounds. Of the patients, 15 of the 95 cases were in people over 65 years of age. Another 20 cases were in Hispanic, black, Asian, or multiracial participants, groups that were disproportionately affected during the pandemic (SN: 4/10/20)
It is important to note that the new results suggest that the vaccine can prevent people from developing serious illnesses if they become infected with the virus. In the clinical trial conducted so far, 11 people fell seriously ill, all of them receiving the placebo.
It is encouraging to see the first results suggest that the vaccine may decrease the severity of the disease, says Nina Luning Prak, an immunologist at the University of Pennsylvania. "It's still a small number, but it's 11 out of 11 versus zero on the other side."
Modern, based in Cambridge, Massachusetts, and the U.S. National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, worked together to develop the vaccine. Previous work has shown that the vaccine elicits an immune response in people who receive it (SN: 18/05/20).
As of October 22, 30,000 participants were enrolled in the company’s final clinical trial, although thousands still needed to receive both vaccines, which receive a one-month separation.
Previous studies have shown that the vaccine is safe. Trial people reported mild to moderate side effects after the second injection, including fatigue, joint pain, and headache. There were no serious reactions. Modern plans to follow participants for two years to more fully monitor vaccine safety.
Both Moderna and Pfizer vaccines depend on messenger RNA or mRNA, a genetic molecule that the "cellular machinery" "reads" to build proteins within cells. For these vaccines, the mRNA contains instructions for building the coronavirus ear protein, which helps the virus enter human cells.
Vaccines induce human cells to make spike protein, and the immune system produces antibodies to bind to spike proteins. These vaccine-stimulated antibodies can prevent the actual virus from infecting healthy cells in the future.
No vaccine using this mRNA technology has ever been used in humans. If these vaccines are successful, this could speed up the vaccine development process. “That’s one of the strengths of the platform,” says Luning Prak. "In a matter of a few minutes, you could basically design a vaccine." This is because these vaccines do not depend on cells grown in the laboratory to produce millions of doses as other types of vaccines do. All researchers need is the genetic code of a particular viral protein, such as the ear protein. While choosing the right protein from many possibilities to generate the best immune response can still be tricky, mRNA vaccines “clearly have a promise,” he says.
The Pfizer and BioNTech vaccine should be kept frozen at ultracold –70 ° Celsius (–94 ° Fahrenheit), making it difficult to distribute. The Moderna vaccine, however, can remain stable at refrigerated temperatures (between 2 ° to 8 ° C or 36 ° to 46 ° F) for 30 days, the company said in a Nov. 16 press release. This could help allocate COVID-19 vaccines in areas without easy access to dry ice or specialized freezers needed for the Pfizer vaccine.