Coronavirus updates: 84% of California population to go on lockdown Sunday night

Dr. Stephen Hahn, the commissioner of the U.S. Food and Drug Administration, was seen arriving at the White House on Tuesday morning ahead of his scheduled meeting with President Donald Trump's chief of staff, Mark Meadows.

It's unclear if Trump is participating in the meeting.

A source told ABC News that the meeting was called amid frustrations that the FDA hasn't moved faster in authorizing emergency use of a COVID-19 vaccine developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech.

Hahn issued a statement ahead of the meeting, defending his agency's timeline.

"Let me be clear -- our career scientists have to make the decision and they will take the time that’s needed to make the right call on this important decision," Hahn said. "We want to move quickly because this is a national emergency, but we will make sure that our scientists take the time they need to make an appropriate decision. It is our job to get this right and make the correct decision regarding vaccine safety and efficacy."

The FDA is already moving at an accelerated pace in going through data related to the vaccine candidate, but it's a process that takes weeks given the sheer volume and the stakes for getting it right.

"The amount of data submitted to the FDA includes thousands of pages of technical information that must be divided up and reviewed by experts from different disciplines. Once the reviews by the various experts are completed, they are then integrated into an overall review," a spokesperson for the agency told ABC News in a statement Tuesday. "Completion of these reviews involves such things as ensuring that the manufacturing process and the controls on manufacturing are appropriate, checking statistical analyses performed to ensure that they were done properly and doing additional analyses, as necessary, to look at the effect of the vaccine on subsets of individuals who might be at greater risk of adverse effects."

Meanwhile, an FDA spokesperson also confirmed to ABC News that Hahn had recently self-quarantined "out of an abundance of caution," following potential exposure at the agency's campus in White Oak, Maryland. He chose a remote location and continued working.

"Dr. Hahn has worked every single day of this pandemic, including weekends, holidays and more," the spokesperson said in a statement Tuesday.

ABC News' Katherine Faulders, Anne Flaherty and Jordyn Phelps contributed to this report.

Formula One champion Lewis Hamilton said he will miss the Sakhir Grand Prix in Bahrain this weekend after testing positive for COVID-19.

After having three negative test results this past week, the 35-year-old British racing driver said he woke up Monday morning with "mild symptoms" and requested another test which came back positive. He said he has immediately gone into self-isolation for 10 days.

"I'm devastated that I won't be racing this weekend," Hamilton said in a statement posted on his official Instagram account Tuesday. "Since we started the season in June, my team and I have been taking all the precautions we possibly can and following the regulations everywhere we've been in order to stay safe."

Hamilton, whose victory at the Turkish Grand Prix in Istanbul on Nov. 15 sealed the Formula One championship and his record-equaling seventh world title, said he considers himself "really lucky" to only have mild symptoms and that he will do his best "to stay fit and healthy."

"Please look after yourselves out there, you can never be too careful," he said. "These are worrying times for everyone and we need to make sure we are looking after ourselves and each other."

People are now required to wear face masks in all indoor public spaces in the Netherlands.

The Dutch government is one of the last in Europe to introduce such a mandate.

The new rule, which came into force Tuesday, applies to everyone over the age of 13 when in publicly accessible, covered places such as airports, barber shops and hair salons, covered car parks and gas stations, public transportation including platforms, town halls and retail stores. Students and teachers will also have to wear masks when walking around school buildings but not when seated during lessons.

Places of worship and buildings not accessible to the general public are exempt.

Those who ignore the mask mandate face a fine of up to 95 euros (about $114).

The former director of the U.S. Centers for Disease Control and Prevention said that although he expects a COVID-19 vaccine to be approved soon, he also anticipates "some bumps in the road."

"When you vaccine millions of people, some people get really sick after the vaccination and you don't know whether that was the vaccine or that was just coincidence. So that has to be studied carefully or you're going to get all sorts of wild rumors flying around," Dr. Tom Frieden, who is now the president and CEO of Resolve to Save Lives, told ABC News chief anchor George Stephanopoulos in an interview Tuesday on "Good Morning America."

"There may be production problems, there may be rumors, there may be people who don't want to take it even if you do have the vaccine," he added. "So this is probably, George, the single most complicated vaccination program in American history."

Although a vaccine may be right around the corner, Frieden said people must remain vigilant this winter by wearing masks, washing hands, practicing social distancing and avoiding indoor gatherings.

"We have to double down on safety protocols or we're going to see the worst season we've yet had for COVID," he warned. "We can all do more."