Based on interim data from a late-stage trial, Moderna said it experimental vaccine is 94.5% effective in preventing Covid-19, becoming the second US drugmaker to report results that far exceed expectations.
Moderna’s interim analysis was based on 95 infections among trial participants who received the vaccine or a placebo. Only five infections occurred in volunteers who received the vaccine mRNA-1273, which is administered in two shots 28 days apart.
The 95 cases of Covid-19 included several key groups who are at increased risk for severe disease, including 15 cases in adults aged 65 and older and 20 in participants from racially diverse groups.
In a statement, Moderna said most side effects were mild to moderate and were generally short-lived. A significant proportion of volunteers, however, experienced more severe aches and pains after taking the second dose, including about 10% who had fatigue severe enough to interfere with daily activities while another 9% had severe body aches.
Unlike Pfizer’s vaccine, Moderna’s shot can be stored at normal fridge temperatures, making it easier to distribute, a critical factor as Covid-19 cases are soaring, hitting new records in the United States and pushing some European countries back into lockdowns.
Moderna expects the vaccine to be stable at normal fridge temperatures of 2 to 8 degrees Celsius for 30 days and it can be stored for up to 6 months at -20 degrees Celsius.
Pfizer’s vaccine must be shipped and stored at -70 degrees Celsius, the sort of temperature typical of an Antarctic winter. It can be stored for up to five days at standard refrigerator temperatures, or for up to 15 days in a thermal shipping box.
The data from Moderna’s trial involving 30,000 volunteers also showed the vaccine prevented cases of severe Covid-19, a question that still remains with the Pfizer vaccine. Of the 95 cases in Moderna’s trial, 11 were severe and all 11 occurred among volunteers who got the placebo.
Together with Pfizer’s vaccine, which is also more than 90% effective, and pending more safety data and regulatory review, the United States could have two vaccines authorised for emergency use in December with as many as 60 million doses of vaccine available this year.
The vaccines, both developed with new technology known as messenger RNA (mRNA), represent powerful tools to fight a pandemic that has infected 54 million people worldwide and killed 1.3 million.