Coronavirus updates: 1st vaccines now on the way to all 50 US states

The Trump administration declined additional doses of the Pfizer coronavirus vaccine late this summer when the pharmaceutical company offered them to the U.S. government, a senior Trump administration official familiar with the matter confirmed to ABC News.

Pfizer may be unable to produce more of the vaccine for United States citizens until June 2021 because it has committed those doses to other countries.

"The U.S. government placed an initial order of 100 million doses for Pfizer-BioNTech’s COVID-19 vaccine, and Pfizer is ready to begin shipping initial doses soon after receiving an Emergency Use Authorization from the FDA," Pfizer told ABC News in a statement.

"Any additional doses beyond the 100 million are subject to a separate and mutually-acceptable agreement. The company is not able to comment on any confidential discussions that may be taking place with the U.S. government."

The development was first reported by New York Times.

-ABC News' Josh Margolin and Eric Strauss contributed to this report.

On Friday, hospitals in Massachusetts will stop offering elective surgeries that can be safely postponed, Gov. Charlie Baker said at a press conference Monday afternoon.

"This action will free up unnecessary staffing and beds," Baker said. "We all know we're in the midst of a second surge. We're seeing a higher number of new cases each day. And in turn, an increase in hospitalizations statewide."

On Sunday, Massachusetts reported 4,747 new infections and a seven-day average testing positivity rate of 5.3%. There are 1,416 people currently hospitalized with COVID-19.

Despite the worsening statistics, the state is better prepared this time around, Baker insisted. In addition to reallocating hospitals resources, the state is ramping up and winterizing testing sites, stockpiling PPE and preparing two field hospitals in Worcester and Lowell.

-ABC News' Kelsey Walsh contributed to this report.

Navajo Nation begins a three-week emergency lockdown on Monday, during which residents are required to remain at home 24 hours a day, seven days a week.

Essential businesses, including grocery stores, gas stations, laundromats, hay vendors and restaurants providing drive-thru or curbside service, may remain open on weekdays between 7 a.m. and 7 p.m. Off-reservation travel is not permitted and on weekends, a full lockdown will be in place.

"The Navajo Nation’s health care system is in a state of major crisis," Myron Lizer, vice president of Navajo Nation, said in a statement. "We cannot be careless and we have to stay the course."

The rules include exceptions for essential workers and emergency situations. Residents are permitted to leave their homes for essential food, medicine and supplies, as well as outside exercise within the vicinity of their homes and wood gathering.

The lockdown rules will be in effect until Dec. 28.

On Monday, Dr. Anthony Fauci painted a grim future for the United States if Americans don't adhere to public health measures during the holidays. "Without substantial mitigation, the middle of January can be a really dark time for us," Fauci said during a news conference held by New York Gov. Andrew Cuomo.

Americans need to keep social distancing until 75% to 80% of the population can get the COVID-19 vaccine, which would provide an umbrella of community-level protection, Fauci explained. "By the time you get to the beginning of April, you’ll start getting people who have no high priority, just the normal man and woman, New Yorker in the street who's well, has no underlying conditions [getting the vaccine]," he added.

As of Monday, New York State's testing positivity rate was 4.7%, according to Cuomo. The governor estimated that more than 70% of infections spreading in the state were connected to small gatherings.

-ABC News' Rachel Katz contributed to this report.