Coronavirus vaccines: Your questions answered

(CNN)There is sorely needed good news on the vaccine front: A second US vaccine has been found to have a high success rate against Covid-19. Moderna announced on Monday that its vaccine was 94.5% effective against coronavirus, according to early data.

Vaccinations could begin in the United States in the second half of December, starting with high-risk groups and becoming available for the rest of the population in spring, according to Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

Here are some answers to common questions about the coronavirus vaccines being developed to prevent Covid-19.

Don't vaccines take years to develop safely? How have these two been developed in just 10 months?

Most vaccines in use today have taken years and, in some cases, decades to develop, but governments have poured huge amounts of money into companies and institutions developing vaccines, with initiatives like Operation Warp Speed in the United States and the Vaccine Taskforce in the United Kingdom.

The pandemic has galvanized the scientific community all around the world, with groups of researchers in dozens of countries on a fast-paced hunt to understand how the virus works. Operation Warp Speed has also drawn up protocols to allow trials to proceed more quickly, and industrial-scale manufacturing of the vaccines has taken place before we knew whether they would be effective. This means we have millions of doses ready to be used. Read More