"Pfizer is not having any production issues with our COVID-19 vaccine," CEO Albert Bourla says. But Human Services Secretary Alex Azar says the company has had problems. Many states say their allocations for next week have been cut, without an explanation. Patrick T. Fallon/AFP via Getty Images hide caption
Vice President Pence receives the COVID-19 vaccine at the White House complex on Friday. Andrew Harnik/AP hide caption
Katalin Karikó works at BioNTech, the company that partnered with Pfizer to make the first COVID-19 vaccine to get emergency authorization in the United States. Jessica Kourkounis hide caption
Dr. Lawanda Jim, Chair of Internal Medicine, receives a COVID-19 vaccine at Northern Navajo Medical Center on Tuesday in Shiprock, N.M. Micah Garen/Getty Images hide caption
Rep. Cedric Richmond, left, speaks with Joe Biden at Columbus Airport in Columbus, Ga., in October. Biden's transition team says he has not had close contact with Richmond, who has tested positive for the coronavirus. Andrew Harnik/AP hide caption
The U.S. Capitol has been hit by the coronavirus like the rest of the country, grappling with protective measures and multiple cases. Al Drago/Bloomberg via Getty Images hide caption
A worker passes through the security gate at the Moderna campus in Norwood, Mass., one of the sites where the biotechnology company is manufacturing its COVID-19 vaccine. Joseph Prezioso/AFP via Getty Images hide caption
California Gov. Gavin Newsom holds up a vial of the Pfizer-BioNTech COVID-19 vaccine this week at a Los Angeles medical facility. Coronavirus cases continue to soar in the state as hospitals struggle to keep up with the surge. Jae C. Hong/AP hide caption
An older sister in Kenya carries her baby sibling. A new study looks at the impact of a big sister's caregiving. Wendy Stone/Corbis via Getty Images hide caption
A health care worker prepares COVID-19 vaccine doses at the Portland Veterans Affairs Medical Center on Wednesday in Portland, Ore. Hospitals across the U.S. began getting their first doses of Pfizer's vaccine this week. Nathan Howard/Getty Images hide caption
President-elect Joe Biden is set to name Brenda Mallory to lead his Environmental Quality Council. Stephanie Gross for Southern Environmental Law Center hide caption
A COVID-19 vaccine made by Moderna is next in line with the Food and Drug Administration for possible authorization for emergency use during the pandemic. Bill Sikes/AP hide caption