These 46 Critical Days Defined Our Year of Living in a Pandemic

The Pfizer-BioNTech vaccine against COVID-19, the first federally approved coronavirus vaccine in the U.S., is administered to health care workers and staff at nursing homes nationwide.

The U.S. death toll from the coronavirus tops 300,000 — the day the country begins dispensing COVID-19 shots in a campaign to stop the pandemic.

The U.S. Food and Drug Administration confirms the effectiveness and safety of the Moderna COVID-19 vaccine, clearing a path to authorization. The potential second COVID-19 vaccine is found to be 95% effective.

A week after the first doses of the Pfizer-BioNTech coronavirus vaccine were administered in the US, a new batch of vaccines, made by Moderna, fanned out across the country. Moderna’s vaccine rollout is four times larger than Pfizer’s.

The first U.S. case of the more contagious COVID-19 variant first reported in the U.K. has been reported in Colorado, a week after British scientists identified the variant.