For low- and middle-income countries, just obtaining doses has been a challenge. And now concerns are being raised about the effectiveness of the more affordable AstraZeneca option.

A small study in South Africa has raised concerns about the effectiveness of the AstraZeneca vaccine, particularly in fighting virus variants.

European Commission President Ursula von der Leyen announced Sunday that AstraZeneca would also deliver the vaccines one week earlier than originally scheduled.

"The companies must deliver. They must honor their obligations," the European Commission's president said after both AstraZeneca and Pfizer said they were experiencing shipping issues.

Almost 150,000 people in India have died from complications of COVID-19, behind only the U.S. and Brazil. India plans to begin inoculating its population of 1.4 billion this month.

The British government has ordered 100 million doses, enough to vaccinate 50 million residents.

Experts say low-risk people in the U.S. will likely be immunized before many high-risk people in poor countries.

The move by Eli Lilly came less than 24 hours after Johnson & Johnson paused further dosing in all of its COVID-19 vaccine candidate clinical trials while it investigated a volunteer's illness.

The company had placed its worldwide vaccine trials on hold for several days. It now says a safety review by regulators and reviewers is complete. No word on when studies in the U.S. might resume.

AstraZeneca, which is working with the University of Oxford, hasn't said what the illness is. It will try to determine whether the illness is related to the vaccine, or just a chance event.