Vaccine appointments in New York City will be rescheduled due to a major winter storm heading toward the East Coast.

The nor'easter is expected to begin Sunday night and could dump up to a foot of snow onto the city.

"Last thing we want to do is to urge our seniors to come out in the middle of a storm like this," NYC Mayor Bill de Blasio said at a press conference Sunday morning. "It doesn't make sense."

-ABC News' Joshua Hoyos

The mass COVID-19 vaccination site at Dodger Stadium, one of the largest in the country, was temporarily halted Saturday after the entrance was blocked by anti-vaccine protesters.

The group carried anti-vaccine and anti-mask signs, leading to a long line of cars waiting to get into the stadium, ABC Los Angeles station KABC reported.

The stadium entrance was closed from about 1:50 p.m. to 2:45 p.m., Los Angeles Fire Department Public Information Officer David Ortiz told ABC News. Vaccinations continued inside as the gate was closed, Ortiz said.

A social media post described the demonstration as "SCAMDEMIC PROTEST/MARCH" and advised participants to refrain from wearing pro-Trump or MAGA attire.

"…we want our statement to resonate with the sheeple," the post read, according to The Associated Press. “No flags but informational signs only.”

No arrests were made as a result of the protests.

Republican Arkansas Gov. Asa Hutchinson said Sunday that vaccine distribution has been "seamless" under the Biden administration.

"In terms of the vaccine distribution, it's been seamless. And I was delighted that we had a ... 14% increase in vaccine supply last week. This is going to be very, very important for us. They said they're going to invoke the Defense Production Act. I don't know the details on that, but anything they can do to speed up the production," Hutchinson said on ABC's "This Week."

"Thank goodness we have that partnership which is good with the federal government. And President Biden and his team is -- is working to assure that partnership and not tear it apart, which I'm very grateful for," he told "This Week" Co-anchor Martha Raddatz.

-ABC News' Jack Arnholz

Dave McGillivray, the race director of the Boston Marathon, has been selected by the state of Massachusetts to run the mass vaccination operations at Gillette Stadium and Fenway Park.

McGillivray owns DMSE Sports, which organizes and manages dozens of outdoor events every year. To help keep DMSE Sports afloat, McGillivray connected with CIC Health -- which operates the mass COVID-19 vaccination sites at Fenway Park and Gillette Stadium -- through the state of Massachusetts.

Now, McGillivray is running logistics for both sites.

"For me, the feeling is so good that the thing that knocked us to our knees is now the thing that is allowing us to do good: that we're keeping people healthy, we're saving lives and we're even bringing our own industry back," McGillivray said in an interview with Boston ABC affiliate WCVB().

Fenway Park is the home of the Boston Red Sox, while Gillette Stadium, located in Foxborough, is the home stadium for the New England Patriots. The Gillette Stadium site opened two weeks ago, with Fenway officially opening Monday. Both sites are expected to administer 5,000 doses per day once fully up and running.

The Boston Marathon, usually held in April, has been postponed to October. The in-person event was canceled in 2020, though it was held virtually.

ABC News' Arielle Mitropoulos contributed to this report.

Dr. Anthony Fauci, the nation's leading infectious disease expert, spoke about the latest updates on the U.S. vaccine rollout during an interview Monday on ABC News Live.

Fauci, director of the National Institute of Allergy and Infectious Diseases, said that he believes the vaccine will be available to everyone beginning in April, but it won't be until the fall that everyone has actually gotten their shot in the arm.

"It will take several months-May, June, July, August- before you really get what I would consider the herd immunity level, which is an estimate, but I think it's a reasonable estimate, namely getting 70 to 85% of the population vaccinated," Fauci, who is also Biden's chief medical adviser, told ABC News Live.

Fauci said that the timeline is not considering a future approval of coronavirus vaccines developed by Johnson & Johnson and AstraZeneca.

"I think if the J&J or the [AstraZeneca] product comes through with an efficacy that's good enough to be able to be in the mix, that will be very helpful to get things done even sooner than we thought," he said.

Fauci also opened up about an incident where he was exposed to a powder substance that was in his mail last year. The powder was later deemed benign, but only after his security detail put on hazmat suits and sprayed him down.

"It frightened the heck out of my children when they found out about it and my wife too," he said. "I mean, I've decided I'm doing something that might be dangerous but that's it, I chose it. My children did not choose that."

Watch Fauci's full interview with ABC News Live at 7 p.m. and 9 p.m. ET Monday.