SOUNDING MORE and more like a coach trying to rally his team against a superior opponent, Gov. Charlie Baker on Friday implored Massachusetts residents to take COVID-19 seriously.

He said infections have been headed in the wrong direction since Labor Day and are rising faster and faster. He insisted the problem for the most part is not at workplaces, schools, or restaurants, but in situations where people let their guard down while engaging in familiar activities in casual settings with people they know.

“It’s the innocent acts of small gatherings where COVID is finding its greatest opportunity to spread,” Baker said at a State House press conference. “People need to change their behavior and get serious.”

The governor is worried about Thanksgiving. He noted Canada celebrated its version of Thanksgiving in October and two weeks later cases in that country exploded.

This second surge is different from the first. The ramp up is slower, the death rate is lower, and infections are rising the fastest among people in their late teens to their late 30s, who are able to weather COVID better than the much older patients who became ill and often died in the spring.

The state set up five field hospitals in the spring to ease pressure on hospitals dealing with COVID cases, but the governor said three of them ended up not being used. On Friday Baker announced a 243-bed field hospital is being set up once again at the DCU Center in Worcester to ease pressure on UMass Memorial Hospital, which is operating at full capacity right now and turning away patients. The field hospital is expected to be up and running the first week of December.

Dr. Eric Dickson, the president and CEO of UMass Memorial, said in the spring the COVID-19 transmission rate was estimated at 2.5, meaning every person infected would go on to infect 2.5 others. Now, Dickson said, the transmission rate is 1.4.

He also said hospital care for COVID-19 patients has improved. He said 108 patients are currently in central Massachusetts hospitals with COVID-19 and only nine are on ventilators. He said the number would have been 30 to 40 last spring. “We really have new strategies and therapies to help people,” he said, adding that a shortage of ventilators is unlikely to be a problem in this second surge.

Dr. Jarone Lee of Massachusetts General Hospital said in a commentary in CommonWealth that he also expects ventilator use to decline, but he worries that many of the machines rely on proprietary parts and supplies. If a machine breaks down, he said, it may take a long time to get it back online. He said the hospital industry may need its own right to repair law to deal with its equipment.