The top U.S. infectious disease expert said Sunday that President-elect Joe Biden's ambitious plan to inoculate 100 million people with the COVID vaccine in the first 100 days of his presidency "is absolutely a doable thing."

Speaking on NBC Television's "Meet the Press," Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said that with the current vaccines and additional vaccines scheduled to come to market soon, combined with adherence to wearing masks and observing social distancing, he believes the U.S. could be in "good shape."

Currently, the U.S. is far from being in "good shape." With nearly 24 million COVID-19 cases, it has more infections than any other country. The rollout of the U.S. inoculation campaign has been problematic with far fewer people inoculated by the end of last year than the Trump administration predicted.

Meanwhile, California's Los Angeles County has become the first U.S. county to record 1 million COVID-19 cases. The impact of the massive number of infections is compounded by the confirmation of the appearance in the county of two mutations of the virus - the British variant and a Denmark variant.

The British variant is highly contagious. Dr. Barbara Ferrer, the county's public health director, said in a statement, "The presence of the U.K. variant in Los Angeles County is troubling."

Researchers are not sure if the Danish variant is as contagious as the British one, but Charles Chiu, responsible for the sequencing of the Denmark strain said Sunday, 'There are worrisome signs that this variant may be highly transmissible."

FILE - Syringes containing the Pfizer-BioNTech COVID-19 vaccine sit in a tray in a vaccination room at St. Joseph Hospital in Orange, Calif., Jan. 7, 2021.

India and Brazil follow the U.S. with COVID infections with 10.5 million and 8.4 million respectively.

Mexico's president said Sunday that his country is complying with a United Nations' request to wealthy countries to delay receiving some of their vaccine shipments, which would allow poorer countries to receive more vaccine doses.

President Andres Manuel Lopez Obrador said Sunday while Mexico's Pfizer vaccines would be delayed, Mexico is "already seeking out other vaccines," including Astra Zeneca, Chinese CanSino and Russian Sputnik V vaccines, according to an Associated Press report.

Brazil approved two vaccines for emergency use against the coronavirus Sunday as the country's death toll from the disease it causes neared 210,000 and some of its hospitals grappled with an oxygen shortage.

The country's health ministry said Sunday that the death toll was nearing 210,000, the second highest in the world after the United States.

Brazil approved emergency use of vaccines from both Britain's Astra-Zeneca and China's Sinovac Biotech Ltd. Hours later, a nurse in Sao Paulo was inoculated with the Chinese vaccine known as "CoronaVac."

Meanwhile in Manaus, the largest city in the Amazon, hospital employees described to the Associated Press having to choose which patients to provide with oxygen as supplies in the remote city dwindled.

Brazil has also recorded cases of a new variant of the virus that is potentially more contagious.

Pakistan also announced Sunday that it had approved the Astra-Zeneca vaccine for emergency use. The South Asian country has confirmed nearly 520,000 cases of the virus, significantly fewer than its larger neighbor India.

Britain announced Sunday that it plans to have every adult in the country, roughly 51 million people, inoculated by September.

"If we can do it faster than that, great, but that's the road map," Foreign Secretary Dominic Raab told SkyNews Sunday.

In many Eastern European countries, skepticism about the safety of the vaccines is high. In Serbia, only 200,000 people out of a population of 7 million, have applied to receive the vaccine. Serbian tennis player Novak Djokovic notably said he did not want to be forced to be inoculated.

Djokovic tested positive for the virus this summer during a tournament he organized with lax restrictions for masks and social distancing.