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Covid-19 Vaccine Shown Effective, Temperature-Stable

Syringe in hand

(Sam Moqadam, Unsplash)

16 Nov. 2020. Interim clinical trial results show the Moderna Covid-19 vaccine prevents infection in 94 percent of cases and can stored for 30 days in normal refrigeration. The findings released by Moderna Inc., and not peer-reviewed, also show the two-dose vaccine is generally well-tolerated with relatively few severe adverse effects experienced after the second injection.

The phase 3, or late-stage, clinical trial enrolled some 30,000 participants at 100 sites in the U.S. The study team is randomly assigning participants to receive Moderna’s experimental mRNA-1273 vaccine or a placebo, with two 100-microgram injections given 28 days apart. The study team is looking primarily for Covid-19 infections occurring within the two weeks following the second injection, as well as adverse effects from the injections within a week after each injection, and at various points over the next two years.

Moderna, a biotechnology company in Cambridge, Massachusetts, reports on the first 95 patients becoming infected with Covid-19 after receiving both injections. The results show 90 placebo recipients became infected within 2 weeks compared to 5 mRNA-1273 recipients, for a protective efficacy rate of 94.4 percent. The researchers also assessed the severity of Covid-19 symptoms among those becoming infected, defined as intensive care unit admission, advanced respiratory distress syndrome, heart and other organ failure, or death. The findings show 11 placebo participants developed severe symptoms compared to none of the mRNA-1273 recipients.

Among the participants reported so far, says Moderna, 15 are age 65 and older, and 20 are from usually under-represented ethnic groups, including Hispanic, Black, and Asian-Americans.

The company says mRNA-1273 was generally well tolerated, with some severe adverse effects — those requiring medical attention in a clinic — taking place mainly after the second injection. Of the severe effects, about 3 percent of participants experienced injection site pain after the first injection, while after the second injection, no more than 10 percent reported fatigue, body aches, joint pain, headaches, other types of pain, and redness at the injection site. The study team says the adverse effects were short-lived.

“This positive interim analysis from our phase 3 study has given us the first clinical validation that our vaccine can prevent Covid-19 disease, including severe disease,” says Moderna’s CEO Stéphane Bancel in a company statement. The company says it plans to ask FDA for an emergency use authorization after completing its analysis of 151 cases and a median follow-up of two months.

Moderna develops vaccines and therapies against infectious diseases with a technology that synthesizes messenger RNA, a nucleic acid based on the genetic code from DNA, and used by cells to produce amino acids in proteins for cellular functions. Moderna manipulates the coding region in messenger RNA chemistry to provide instructions for cells to produce proteins with specific medicinal properties. For protective vaccines, Moderna delivers messenger RNA with instructions for cells to produce proteins with enough resemblance to viruses to generate an immune response, but are still safe for the recipient.

The company reports as well that mRNA-1273 is more stable under normal refrigeration for longer than previously thought. Moderna says the vaccine remains stable in a standard home or medical refrigerator for 30 days at a temperature of  2° to 8° C , or 36° to 46° F after thawing. The company previously estimated mRNA-1273 could remain stable for 7 days at those temperatures. Longer shipping and storage times, up to 6 months, require freezing at -20° C, or -4° F.

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