What to Know About the World’s Top Covid-19 Vaccines

What you should know about the world's best Covid-19 vaccines

The Health and Science DeskTracking the coronavirus

Oxford-AstraZeneca
Efficacy: 62-90%, depending on the dose
Dose: 2 doses 4 weeks apart
Storage: Keep in the refrigerator for at least 6 months

Previously approved in the UK, India and several other countries, this shot is cheap and easy to store, which raises hopes that it could protect most of the world. However, many scientists have been puzzled by data showing that its effectiveness may depend on the strength of the starting dose or the gap between doses.