The pandemic reached alarming new levels Thursday as confirmed coronavirus cases in Massachusetts surged by nearly 6,500, shattering a record set just a day earlier, and the nation recorded 3,100 deaths from COVID-19, the highest single-day toll to date.
State public health officials reported 49 more deaths, bringing the total during the pandemic to 10,637. Cases rose to 232,264, and new data showed that nearly 100 of the state’s 351 cities and towns are considered high-risk.
With the virus spreading at a dangerous rate, Governor Charlie Baker said the state will open a field hospital for patients in Lowell in the coming weeks, in addition to one slated to open Sunday in Worcester.
“Obviously the numbers that were reported yesterday indicate that we have community transmission across the Commonwealth,” Baker said after touring the hospital at the DCU Center.
Baker was referring to the 4,613 new cases reported Wednesday, the highest single-day tally until Thursday’s total surpassed it by more than 1,800. The Thursday figure included 680 cases from before Dec. 1 that were reported late because of a technical issue, officials said.
Despite the record number of positive tests, Baker did not announce any further steps to curtail the spread, even as Mayor Martin J. Walsh warned of possible new lockdown measures. Earlier this week, Baker said the state would continue to track public health data but had no plans for “additional closures or restrictions.”
“One day does not make a trend,” the governor said Thursday, before the second consecutive day of record-setting cases was announced. “If you look at the slope of the line, throughout the fall it’s completely different than the slope of the line in the spring” when the surge was far more accelerated.
But medical specialists warned that the current surge likely does not include exposures during Thanksgiving gatherings and that more alarming numbers are ahead.
Since it can take up to 14 days for a person to test positive for COVID-19 after exposure — and sometimes far longer for an infected person to become seriously ill — current data do not yet reflect the expected post-holiday wave of new cases, hospitalizations, and deaths, they said.
“The scary part is that we are not seeing the hospitalizations and deaths related to the Thanksgiving holiday season yet,” said Dr. Jose Figueroa, an assistant professor at Harvard Medical School and Harvard T.H. Chan School of Public Health. It could be up to five weeks from now before people who were infected during travel or family gatherings reach the point of critical illness, he said.
Figueroa said there is a light at the end of the tunnel, with multiple vaccines likely to become available in the coming months, and possibly before the end of the year. But he said that already high levels of community spread accelerated by back-to-back holidays paint a concerning picture of the weeks ahead.
The same factors that led some people to flout public health guidance over Thanksgiving will be at play over the winter holidays, he said — the desire to see family, cold weather driving people to gather indoors, exhaustion with pandemic rules.
National data released Thursday showed that the number of Americans hospitalized with the virus eclipsed 100,000 for the first time and new cases have begun topping 200,000 a day. A new national forecast released by the CDC projects a rising number of deaths over the next four weeks, with 9,500 to 19,500 deaths expected in the week of Christmas alone.
On Wednesday, the head of the Centers for Disease Control and Prevention said the upcoming months could be “the most difficult in the public health history of this nation” because of the stress on the health care system.
“The reality is, December and January and February are going to be tough times,” said Dr. Robert Redfield. Total deaths could approach 450,000 by February if people don’t follow public health recommendations to curb the virus’s spread, he said.
In Massachusetts, officials said more than 49,000 people were estimated to have active cases of the virus, and 1,324 were hospitalized with COVID-19.
The statewide average daily rate was 35.7, up from 34.9. In Boston, the average daily rate of infection per 100,000 residents was 31.7, down from 33.9 last week.
Walsh said the city had recorded 825 new cases in the past two days. Since Friday, the number of patients hospitalized with COVID-19 had risen by 70.
Visibly frustrated, Walsh said at a news conference that if Boston’s infection rate remains high, he may be forced to shut down the city.
“That’s the next step. And we’ve done that before,” he said. “We’re three weeks away from Christmas. Our retailers need people to go in and shop in [stores]. Our restaurants need people to eat in. People [working], they need to make money.”
“But if these numbers continue to go up, maybe Tuesday I’m standing here . . . could be talking about putting plans down for shutting things down,” he said.
Other states are enacting tougher measures.
Rhode Island is in the middle of a two-week economic “pause’' to restrict public interaction.
“The data is very concerning,” Governor Gina Raimondo said Thursday. “We are far past the peak we had in the spring, and this wave certainly seems to be much more dangerous, which is why I decided to impose new restrictions in the past few weeks.”
In Rhode Island, bars, casinos, and fitness centers were ordered to close and companies ordered to allow employees to work from home in an effort to slow the spread of the virus.
In California, regions of the state with especially low hospital capacity due to the virus will face stay-at-home orders in the coming days, Governor Gavin Newsom announced Thursday.
In Massachusetts, the state reported that the seven-day average rate of positive tests, which is calculated from the total number of tests administered, was at 5.3 percent. The lowest observed figure for that metric — a number watched closely by state officials — is 0.8 percent.
The state said the rate would be 7.32 percent if the effect of college testing programs — in which asymptomatic people can be tested repeatedly in an effort to rapidly identify new cases — is factored out.
The seven-day average of hospitalized virus patients rose from 1,100 to 1,151. The lowest that metric has been is 155.
In another worrisome sign, data released Thursday by the Massachusetts Water Resources Authority showed that traces of the virus continued to rise in the wastewater at the Deer Island treatment plant.
Both the northern and southern sections of the water authority reached their highest levels yet of the second surge. The data included tests conducted up to Tuesday.
Like other metrics maintained by Massachusetts, the wastewater tests paint a picture of a state that appeared to have gotten the virus under control over the summer but then saw a gradual rise — and a marked acceleration in October.
Baker said the state expects to receive about 300,000 doses of a vaccine by year’s end. Officials plan to file a plan for distributing the vaccine on Friday, he said.
“Based on the feedback we’ve gotten from the federal government, we expect — and admittedly, we’ll see how all this all plays out — the beginning of this will probably be a little lumpy,” he said.
Those on the front lines of the fight against the pandemic will likely be first up for vaccinations, Baker said.
Good news on the vaccine front notwithstanding, residents still need to take precautions against spreading the virus. But the encouraging news does not mean “that we are able to flip the switch and suddenly return to normal,” Baker said.
“People need to stay vigilant and they need to keep doing the things that we know keep the virus in check,” he said. “Wearing face coverings, avoiding groups, keeping our distance, staying for the most part with the people that we live with.”
Martin Finucane, Dasia Moore, and Felicia Gans of the Globe staff contributed to this report.