President-elect Joe Biden announced on Tuesday to distribute 100 million doses of a coronavirus vaccine to Americans in the first 100 days of his administration.

"This will be one of the hardest and most costly operational challenges in our nation's history," Biden stated at an event held in Wilmington, Delaware on Tuesday to introduce the members of his administration's health care team. Biden called on Congress to issue financial support early to help with his propose vaccine distribution plan.

"We need Congress to finish the bipartisan work that's underway now or millions of Americans might wait months longer to get the vaccine," Biden continued. "Developing a vaccine is only one herculean task. Distributing it is another herculean task."

Biden will become the next president of the United States on January 20, 2021, known as Inauguration Day. Before and after that date, Biden urges all Americans to follow public health measures like social distancing, hand washing and wearing a mask to keep the number of coronavirus infections low before the roll out of a vaccine.

Vaccines developed by the frontrunners Pfizer (PFE  )-BioNTech (BTNX  ) and Moderna (MRNA  ) require two shots to be effective at preventing infection. The U.S. Food and Drug Administration on Tuesday found that the Pfizer-BioNTech shot is has an efficiency of at least 50% after the first dose and does not produce any severe adverse side effects.

Despite vaccine optimism, health experts warn that the United States has yet face the peak of its coronavirus outbreak. Dr. Anthony Fauci, the nation's leading infectious disease expert, stated on Tuesday that the U.S. will see a spike in infections from Thanksgiving travelers in a week or two, just before the Christmas and New Year's holidays.

"We're going to enter into the Christmas season, again with more travelling and with more congregating at family and social gatherings," Fauci told The Wall Street Journal's CEO Council summit on Tuesday. "We're in for a very challenging period ahead."

Average deaths attributed to the coronavirus have reached an alarming 2,200 per day in the U.S., matching the peak the nation saw during the outbreak's first wave back in April, according to data compiled by The COVID Tracking Project. More concerningly, average daily infections surpassed 200,000 for the first time since the beginning of the pandemic.

The nation's coronavirus outbreak has resulted in more than 285,000 deaths and over 15 million confirmed cases. The U.S. added over 1 million cases in the past five days.