Moderna says its vaccine is 94.5% effective in preventing COVID-19

"The range of minor adverse effects reported are unsurprising and typical of almost any vaccine. These reactions tend to be local to where the injection was given and are rarely long-lasting or severe.

"Although they reported efficacy being over 94 percent, there is statistical uncertainty in this; but based on these data, the likely efficacy will be better than 85 percent which would be greater than most scientists would have expected.

"This is the first study to report on severe cases and, while uncertainty remains, the finding of no severe cases with the vaccine and 11 cases with placebo is very strong evidence that the vaccine prevents severe as well as mild disease. It is likely that convincing evidence in respect to deaths will probably only be obtained when the vaccine is in use.

"A wide range of people with illnesses and from minority groups were included in the trials as well as substantial numbers of older patients. We will need much more data and a full report or publication to see if the benefit is consistent across all groups, notably the elderly, but this is definitely encouraging progress."

PETER OPENSHAW, PROFESSOR OF EXPERIMENTAL MEDICINE AT IMPERIAL COLLEGE LONDON

"This news from Moderna is tremendously exciting and considerably boosts optimism that we will have a choice of good vaccines in the next few months."

"This latest press release is based on a study of 30,000 U.S. adults, including many high-risk or elderly persons. This gives us confidence that the results are relevant in the people who are most at risk of COVID-19 and in most need of the vaccines."

"Moderna have also announced that the vaccine can be kept in a conventional freezer (-20 degrees Celsius) for up to  6 months, and that once thawed the vaccine can be kept for up to 30 days at standard refrigerator (2 to 8 degrees centigrade). This makes the vaccine much easier to deliver.

"In terms of side effects, news is also quite good. The first dose caused injection site pain in in about 3 percent of people; the second dose was associated with transient generalized symptoms in about 10 percent of people with fatigue, muscle aches and flu like symptoms. This seems to indicate that they got the dose about right with acceptable adverse events. These effects are what we would expect with a vaccine that is working and inducing a good immune response."

"We need more complete details than we have in this press release, but this announcement adds to the general feeling of optimism about vaccines for COVID-19. What we still don't know is how long any protective immunity may last. For that, we will need to wait."

Follow our full coverage of the coronavirus pandemic here.