Nov. 16, 2020 -- The Moderna vaccine in development to prevent COVID-19 is 94.5% effective in early results and is generally well tolerated, the company announced early Monday. The product can also be stored at temperatures common to many doctors’ offices, pharmacies, and hospitals.

The first interim results of the phase III trial are based on 95 participants with confirmed COVID-19 illness. The independent National Institutes of Health-appointed Data Safety Monitoring Board found that 90 of the positive COVID-19 cases were in patients who received a placebo, compared to five patients who received the vaccine, which means the vaccine is 94.5% effective.

Eleven cases of severe COVID-19 also were reported in the interim data, all of which occurred in the placebo group.

"This positive interim analysis from our phase III study has given us the first clinical validation that our vaccine can prevent COVID-19 disease, including severe disease,” Stéphane Bancel, chief executive officer of Moderna, said in a statement.

The study population included people who could be at higher risk for COVID-19, including 15 adults ages 65 and older and 20 participants from diverse communities.

Safety Data

The Data Safety Monitoring Board found that the vaccine was generally safe and well tolerated. Most after effects were mild to moderate, and generally short-lived, according to a company news release.

Injection site pain was reported in 2.7% of participants after the first dose. After the second dose, 9.7% of participants reported fatigue, 8.9% reported muscle pain, 5.2% reported joint pain, 4.5% reported headache, 4.1% reported pain, and 2.0% reported skin irritation or redness at the injection site.

Moderna plans to request emergency use authorization from the FDA in the coming weeks. The company expects the EUA will be based on more study data, including a final analysis of 151 cases with a median follow-up of more than 2 months.

Moderna also plans to seek authorizations from foreign regulatory agencies.

The company expects to have about 20 million doses ready to ship in the United States by the end of the year. The company also claims it remains on track to manufacture 500 million to 1 billion doses globally in 2021.

Moderna is developing distribution plans with the CDC, the federal government's Operation Warp Speed, and McKesson, a COVID-19 vaccine distributor under contract with the US government.

Refrigeration Requirements

Shipping and storage of the vaccine for up to 6 months can be done at -20 Celsius (about -4 Fahrenheit ), a temperature equal to most home or medical freezers, according to Moderna. After thawing, the company expects the product will remain stable at standard refrigerator temperatures of 2° to 8°C (36° to 46°F) for up to 30 days within the 6-month shelf life.

In contrast, the similar Pfizer vaccine – which early results show has a 90% effective rate, requires shipment and storage at "deep freeze" conditions, –70° C or –80° C, which is more challenging.

Moderna's vaccine can be kept at room temperature for up to 12 hours.