COVID-19 numbers have been rising sharply in Mass. These 7 charts show just how fast

The possibility that the Omicron coronavirus variant might sweep across the globe has generated alarm and grim headlines in the past week. But even as it has grabbed the spotlight, the Delta variant, which officials say constitutes nearly 100 percent of the cases in the United States, continues to infect people.

In Massachusetts, COVID-19 case totals have gone up more than 150 percent and hospitalizations have nearly doubled in the past several weeks. Deaths have not risen as sharply. Here’s a look at those metrics and several others that are sending disturbing signals about where the pandemic might go next in the state:

Cases

In late October, COVID-19 cases were on a plateau after declining somewhat from a spike in September. Then the case numbers began marching upward again.

On Nov. 2, the seven-day average of reported COVID-19 cases was 1,180. As of Dec. 2, the number was 2,993, a 154 percent increase, according to data from the state Department of Public Health.

Low numbers were reported as people relaxed over the Thanksgiving holiday and weekend. But the seven-day average got a dramatic boost with single-day increases of 4,838 cases on Dec. 1 and 5,170 on Dec. 2.

Cases this year compared with last year

In an interesting twist, case numbers at this point are similar to the numbers Massachusetts saw at the same time last year, though this year the numbers are lifting off from the plateau after the September spike, rather than from extremely low levels as they did in the late summer and early fall of 2020.

Hospitalizations

On Nov. 4, COVID-19 hospitalizations dipped to 502. On Dec. 1, there were 989, a 97 percent increase.

Hospitalizations due to breakthrough infections

State data also offers a look at how many fully vaccinated people are among those hospitalized for COVID-19. Those breakthrough case numbers have seen a similar increase percentage-wise as the total, rising from 168 on Nov. 4 to 370 on Dec. 1, or 120 percent. The vaccines, even though they are considered the most important tool in fighting the pandemic, are not 100 percent effective.

Test Positivity

The percentage of COVID-19 molecular tests that turn out to be positive began to climb around the beginning of November, the same time as the two other metrics. On Oct. 26, it was 1.67 percent. On Dec. 1, the positivity rate had nearly tripled to 4.94 percent. (Note: The overall positivity rate number includes the results of routine college surveillance testing of people who are asymptomatic. When those tests are factored out, the positivity number as of Dec. 1 was 7.63 percent.)

Deaths

The trend in the seven-day average of daily reported COVID-19 deaths has not been as clear as it has been in cases and hospitalizations. It has fluctuated from around 10 to 15 deaths per day since late October. Experts and officials have said that they hope that, thanks to vaccinations, deaths will stay low even as cases climb.

Looking ahead: Wastewater surveillance data

The wastewater coming into the Massachusetts Water Resources Authority’s Deer Island treatment plant is showing increasing traces of the SARS-CoV-2 virus, which experts believe could be a harbinger of still more cases to come. Cambridge-based Biobot Analytics, which tests the water for the MWRA, says it has found that the amount of virus in the wastewater is correlated with newly diagnosed coronavirus cases four to 10 days later.

What it means

Experts say the numbers are concerning — and it’s time for people to make sure they’re vaccinated and boosted, and to take precautions.

“It’s a reminder that COVID is far from gone,” said Dr. Paul Sax, clinical director of the Division of Infectious Diseases at Brigham and Women’s Hospital.

“There’s a lot of COVID in the community right now, so people need to be careful. The severe cases continue to occur mostly in unvaccinated people, and in people who were vaccinated but have other medical conditions that make them less likely to respond to treatment,” he said in an e-mail.

“Right now we’re on a trajectory very similar to last winter, hence our strong push to get everyone either their first shot (if unvaccinated) or their third (if it’s been six months or more since their second shot),” he said.

‘It’s more risky out there. There’s more COVID. The vaccine efficacy is waning. We’re definitely seeing patients admitted due to breakthrough infections’

Dr. Shira Doron

Dr. Sabrina Assoumou, an infectious disease physician at Boston Medical Center and an assistant professor at the Boston University School of Medicine, said, “We have the solution, and it’s called vaccination. If you haven’t been vaccinated yet, this is the time to get vaccinated. If you’re already vaccinated, it’s time to get a booster to provide you that extra protection that you’re going to need.”

She also said people should wear masks in indoor public spaces; get tested, including using rapid, at-home tests; and improve ventilation.

Deaths “have not been rising yet at the same level we would have expected,” said Assoumou. She said she was hoping that, thanks to vaccinations, “We’re getting to a point where there’s an uncoupling of number of cases compared to the number of deaths.” She noted, however, that increases in deaths have tended to lag increases in cases by several weeks.

Dr. Shira Doron, an infectious disease physician who is the hospital epidemiologist at Tufts Medical Center, said the increases in the coronavirus metrics are “not good news, obviously.”

“It’s more risky out there. There’s more COVID. The vaccine efficacy is waning. We’re definitely seeing patients admitted due to breakthrough infections,” she said.

But she also sounded an optimistic note, saying there has has been “to a large extent, a decoupling of cases and hospitalizations.”

The breakthrough hospitalization data also does not provide the full picture because, for example, it can include people who were hospitalized for other reasons who were then tested and found to have COVID-19, Doron said.

Efforts need to be redoubled on vaccinations, boosters, testing, and treatments such as oral antivirals and monoclonal antibody therapy, she said.

Assoumou said, “We have all the tools to enable us to address this high number of cases. ... Let’s use them.”

Felice Freyer and Sahar Fatima of the Globe staff contributed to this report.