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Charts: With Delta variant on the loose, Mass. coronavirus metrics are continuing to rise

Caridad Lendof received her first dose of the Moderna vaccine from RN Solennys Fernandez.Suzanne Kreiter/Globe Staff

The Delta variant continues to fuel increases in Massachusetts coronavirus cases and hospitalizations, but the number of daily deaths remains in the single digits, according to data from the state Department of Public Health.

Officials and experts say the situation in highly-vaccinated Massachusetts is better than in other less-vaccinated states. At the same time, they don’t know what will happen next - and they’re continuing to urge unvaccinated people to protect themselves and others by getting their shots.

“We certainly have to be wary,” said Dr. Philip Landrigan, director of the Global Public Health Program at Boston College. “All of those numbers are going in the wrong direction.”


“What it reflects is the fact that the very highly contagious Delta variant is loose in our society, and it’s spreading around, and it’s probably going to spread more in another few weeks” when students come back to colleges as well as primary and secondary schools, he said.

Here’s a roundup of some key coronavirus charts that show where we stand in the battle against the pandemic. The data is current as of the end of Monday.


It looked as if the pandemic was finally tamed when the seven-day average of reported cases hit a low of 52 a day on June 28. But then the Delta variant arrived. The seven-day average has now soared to 1,126 a day, more than 21 times higher.

Cases overall

This chart shows the seven-day average of reported cases since the beginning of the pandemic. The state saw two major surges. Then, as the surge this past winter was waning this spring, there was a “bump” in cases. The current increases have not yet reached the levels of that bump.


The number of coronavirus hospitalizations bottomed out at 80 on July 4. The number of hospitalizations is now up to 402, more than five times higher.


Hospitalizations overall

This chart shows hospitalizations since the beginning of the pandemic, putting the current increase in perspective.


The number of daily deaths reported from the coronavirus slowed to a trickle by mid-July. On at least two days there were zero coronavirus deaths reported. The seven-day average has been edging up since then, but it’s still in the single digits, reaching 7 on Monday.

The wastewater signal

In a worrisome sign, the amount of coronavirus in Boston area wastewater is on the rise again, a possible signal of case increases ahead.

The pilot program tests for SARS-CoV-2 RNA copies per milliliter of wastewater at the Massachusetts Water Resources Authority’s Deer Island treatment plant. Officials think the tests can serve as an early warning system for surges in cases. Cambridge-based Biobot Analytics, which conducts the tests, says it has found that the amount of virus in the waste water is correlated with newly diagnosed coronavirus cases four to 10 days later.

Dr. Paul Sax, clinical director of the Division of Infectious Diseases at Brigham and Womens Hospital, said more case increases are likely ahead, citing the waste water data. He emphasized the importance of people getting vaccinated.

“All hospitals are seeing way more cases than we did in June. Many are unvaccinated, and some are medically complex and ‘tipped over’ by contracting COVID,” he said in an e-mail. “Fortunately, fully vaccinated people by and large are still spared severe disease and hospitalizations. The [vaccines] aren’t 100 percent effective, but good enough that anyone who isn’t vaccinated should be strongly encouraged to do so as soon as possible.”


Experts believe that, because of the vaccines, which are highly effective against severe disease and death, there will be a “decoupling” of case numbers from hospitalization and death numbers.

Dr. Shira Doron, an infectious disease physician who is the hospital epidemiologist at Tufts Medical Center, said that appears to be happening in Massachusetts, but she emphasized more people still need to get their shots. “We absolutely have to get more people vaccinated with whatever aggressive means possible, including a very active effort to use vaccine mandates in any sector where it can be done,” she said.

Landrigan said, “We absolutely need the vaccine. The vaccine keeps people alive.”

In addition, when schools reopen in the coming weeks, all teachers, students, and staff should wear masks, vaccinated or not, Landrigan recommended, citing guidance from the American Academy of Pediatrics. He also recommended that adults wear masks when in indoor public spaces. (The US Centers for Disease Control and Prevention recommends masking in indoor public spaces in substantial and high transmission areas. All of Massachusetts is now considered either a substantial or high transmission area.)

When will the numbers start to drop again?

“I don’t know,” said Landrigan. “As long as there is a reservoir of unvaccinated people in the population, the virus is going to continue to circulate.”


Doron said that in the best-case scenario, the state may be seeing the worst of the Delta variant’s effects now or within a couple of weeks.

“I think we can probably handle that,” she said. “If that’s the case, the current rules and regulations in our state are probably just fine.”

“The worst-case scenario is that this keeps going up and up, we don’t see a downturn,” and hospitals begin to get overwhelmed, she said. At that point, she said, not only increased vaccinations but mask mandates, restrictions on gatherings, and other measures would be needed.

Doron said there are some indications that the virus may be about to loosen its grip on Massachusetts and the rest of the country, but the virus is unpredictable and has taken surprising turns before. “I don’t know what makes the virus go up and down, up and down,” she said. “I strongly believe that no one knows what is going on.”

Martin Finucane can be reached at martin.finucane@globe.com.