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

Scientists have developed dozens of Covid-19 vaccines at record speed.

Here are the leading products →

Pfizer-BioNTech
Efficacy: 95%
Dose: 2 doses, 3 weeks apart
Storage: Freezer storage only at –94°F

This was the first Covid-19 vaccine to get emergency authorization in the United States, and it has been greenlit in many other countries. It offers strong protection against illness from the virus. No serious health problems have been linked to the shot, though some people get fatigue, fever and muscle aches.

Moderna
Efficacy: 94.5%
Dose: 2 doses, 4 weeks apart
Storage: 30 days with refrigeration, 6 months at –4°F

Moderna’s vaccine, like Pfizer’s, offers terrific protection against Covid-19 and sometimes comes with mild side effects. But unlike Pfizer’s shot, Moderna’s does not need to be stored at ultracold temperatures, making it better suited for smaller clinics and remote areas.

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

Authorized so far in Britain, India and several other countries, this shot is cheap and easily stored, raising hopes that it could protect most of the world. Many scientists were puzzled, however, by data showing that its efficacy may depend on the strength of the initial dose or the gap between doses.

Johnson & Johnson
Efficacy: Unknown
Dose: 1 dose
Storage: Up to 2 years frozen at –4° F, and up to 3 months refrigerated

The Johnson & Johnson vaccine is expected to release results from its late-stage clinical trial this month. If the shot works well, it could have a big impact on the pace of vaccinations in the U.S. because it is given in one dose instead of two.

Novavax
Efficacy: Unknown
Dose: 2 doses, 3 weeks apart
Storage: Stable in refrigerator

Novavax, a little-known Maryland company, made waves in August when early data showed that its Covid vaccine prompted a surprisingly robust immune response in people and monkeys. But since then it has run into big delays, including problems with production. Still, Novavax started its final stage of testing in the U.S. in late December.

Russia’s Sputnik V
Efficacy: 91.4%
Dose: 2 doses, 3 weeks apart
Storage: Freezer storage

The Gamaleya Research Institute, part of Russia’s Ministry of Health, has said that its Sputnik V vaccine has an efficacy rate of 91.4 percent. The country began a mass-vaccination campaign — even though data from late-stage trials has not yet been shared publicly. Sputnik V is now also being distributed in Argentina, Belarus and other countries.

Chinese Vaccines

China has pledged to be the primary vaccine provider for the developing world. A state-owned company called Sinopharm claims that its vaccine has a 79 percent efficacy rate, though it has not provided data. Another vaccine, made by the Beijing-based Sinovac, is estimated to have an efficacy rate between 63 and 78 percent, though the full dataset has not been released.