Vice President Mike Pence received a second dose of the Pfizer vaccine at his home Thursday, his press secretary, Devin O’Malley, told ABC News.

Second lady Karen Pence also received a second dose of the Pfizer vaccine, her Director of Communications, Kara Brooks, told ABC News.

ABC News' Ben Gittleson and Elizabeth Thomas contributed to this report.

Massachusetts is escalating all hospitals to Tier 4 status, the "highest level of concern," which indicates active, ongoing constraints warranting Department of Health intervention, Gov. Charlie Baker announced Thursday.

The number of people in hospitals has jumped by 145% and intensive care unit admissions leapt by 111% over the last six weeks, Baker said.

Hospitals were 65% full on Thanksgiving but are now 84% full, he said. ICU capacity went up from 50% at Thanksgiving to 75%.

“Our hospital capacity limits are being stretched to their limit,” Health and Human Services Secretary Marylou Sudders said.

Hospitals with severe capacity constraints may begin on Thursday to request a temporary exemption from the mandated nurse-to-patient ratios in the ICU, Baker said.

A hospital system may exercise this exemption only if it has capacity of less than 20% across its system for more than seven days, and if the chief executive officer has attested in writing that all nonessential invasive procedures have stopped.

The governor also said he’s extending the state’s restrictions around gatherings and businesses through Jan. 24. Gatherings are limited to 10 people indoors and most businesses, including restaurants, are limited to 25% capacity.

ABC News' Arielle Mitropoulos contributed to this report.

Daily cases may double in most New York City boroughs within the next four weeks, while in the Washington, D.C. area, case numbers are expected to grow well into January, models from PolicyLab at Children’s Hospital of Philadelphia predict.

PolicyLab’s latest forecast shows cases doubling in the Atlanta area in January. Across Georgia, ventilator use has been up 60% since Christmas, PolicyLab said.

In Texas, “projections for Dallas, Houston, San Antonio and Austin show no signs of slowing in the coming weeks,” PolicyLab said. “These forecasts come as Texas climbs to 45% COVID ICU occupancy and 200 deaths a day.”

In the Pacific Northwest, “concerns are growing,” PolicyLab said, “as some of the highest transmission rates in the country were observed in the state of Washington this past week.”

The Seattle area could see cases double over the next few weeks, PolicyLab said.

Hard-hit Los Angeles is “near its peak,” according to PolicyLab’s model.

ABC News' Brian Hartman contributed to this report.

The COVID-19 variant first found in the United Kingdom has now been detected in eight states, with officials announcing cases Thursday in Pennsylvania, Texas and Connecticut.

In Pennsylvania, the case was confirmed in Dauphin County, which encompasses Harrisburg.

“This individual tested positive after known international exposure. A case investigation and contact tracing were performed to identify, inform and monitor anyone who was in close contact with this individual,” state officials said. “The individual had mild symptoms, which have since been resolved while they completed their isolation at home.”

“Pennsylvania has been preparing for this variant by working closely with the Centers for Disease Control and Prevention (CDC) and has been sending 10-35 random samples biweekly to the CDC since November to study sequencing and detect any potential cases for this new COVID-19 variant,” Secretary of Health Dr. Rachel Levine said in a statement. “Public health experts are in the early stages of working to better understand this new variant, how it spreads and how it affects people who are infected with it.”

The variant was also confirmed for the first time in Texas on Thursday, officials said. The case was in Harris County, which encompasses Houston.

The man has had no history of travel and is stable in isolation, Harris County officials said.

Epidemiologists are working to identify and quarantine his close contacts.

In Connecticut, two unrelated cases were confirmed in New Haven County, Gov. Ned Lamont said Thursday.

The two people are between the ages of 15 and 25 and both "recently traveled outside Connecticut -- one to Ireland and the other to New York State -- and both developed symptoms within 3 to 4 days of their return," Lamont's office said.

"They are in the process of being re-interviewed by public health officials in light of the identification of the UK variant as the cause of their illnesses," his office said. "One individual has completed their self-isolation period, and the other is self-isolating at their home and will remain there until they are 10 days past the onset of symptoms and they are symptom free."

COVID-19 mutates regularly and the variant first detected in the U.K. has now been confirmed in at least eight states: Georgia, New York, Colorado, California, Florida and now Pennsylvania and Texas. While it appears to spread more easily, there's no evidence that it's more deadly.

The United Kingdom saw another day of rising coronavirus cases, deaths and hospitalizations, according to the British government.

The nation recorded 54,940 new cases Sunday, bringing the total number of cases to 3,072,349, the health data showed. The seven-day average for new cases rose from 21,698 on Dec. 10 to 61,106 on Jan. 1, the British government said.

The U.K. saw 563 new COVID-19-related fatalities Sunday, according to the health data. The country has 81,431 total deaths since the start of the pandemic, the government said.

There are currently 32,294 people hospitalized in Britain. The seven-day average for new hospital admissions rose from 1,728 on Dec. 10 to 3,345 on Jan. 1, officials said.