Massachusetts is entering spring on a hopeful note. The state earlier this week released its plan to open vaccination eligibility to all adults on April 19, and a few sunny, warm days have begun to coax residents out of their homes and winter coats.
But beneath the air of optimism lies a problem, epidemiologists caution: COVID-19 cases, after declining sharply in early February, have plateaued at an average of 1,500 per day, and the threat of another surge remains.
“I think we’re just in a race against time to vaccinate people,” said Helen Jenkins, a Boston University epidemiologist. “I definitely am concerned that we could see things start to tick up.”
After January highs of 5,000-plus cases per day, the current coronavirus outlook represents a dramatic improvement. But at the same time, with more contagious variants of the virus circulating in the state and the vaccine rollout still far from complete, experts say stalled progress is a concern. Several urged the state to slow or stop its reopening plans — set to advance to Phase 4, Step 1 on Monday — until more people have been protected and transmission slows.
“I do have concerns about moving to Phase 4, that that will just help encourage [spread],” Jenkins said of the move, which will raise capacity limits at some businesses and allow more in-person activities to resume, including attending entertainment venues and gathering on wedding dance floors. “I do think that we need to be very cautious because of new variants.”
In a statement Thursday, the Baker administration cited public health metrics “continuing to trend in a positive direction” in its decision to move the state into Phase 4, noting that hospitalizations have dropped by 20 percent and deaths by 24 percent since March 1. Baker also said Wednesday that he’s confident more than 4 million Massachusetts adults will be vaccinated by July 4.
This is not the first time the state’s progress in reducing transmission has flatlined. Last summer, the state breathed a sigh of relief after emerging from its first deadly surge. Reopening began, bringing the state out of its strictest lockdowns.
But during the summer plateau, the daily average caseload was 150 to 300 before steadily trending upward in October to create a fall spike. Over the past month, the number of positive cases has also remained steady but at a level as much as 10 times higher than that of the summer months.
The disparity between the two plateaus partially has to do with an increase in testing. Some 1.2 million tests were conducted every two weeks in February, while roughly 250,000 were conducted every two weeks in August. Even so, the percentage of those tests that come up positive — a metric known as the percent positivity rate — has been much greater in the last six weeks than during the summer.
“Cases are obviously much lower than they were [at the beginning of the year], but they’re still reasonably high by the standard of what case numbers have been across the whole pandemic,” said Dr. Ashish Jha, dean of the Brown University School of Public Health.
With variants of the virus spreading in the United States — one of which is thought to be far more contagious and others that are thought to be more resistant to the current vaccines — Jha said there is more pressure than ever to vaccinate people quickly and avoid a wave of springtime infections.
Some states beyond Massachusetts are already seeing such a surge. Cases are rising by more than 10 percent in 14 states this week compared to last week, according to Johns Hopkins University data. Half of those states saw a rise of more than 20 percent. Massachusetts, by comparison, remained somewhat steady at an 8 percent rise.
Italy, which has long acted a bellwether for the United States’ pandemic trajectory, underwent a month-long plateau from late January to late February before surging once more. There will be a three-day national lockdown in the country over Easter.
So far Massachusetts has not seen a similar jump, but whether the plateau here will balloon into a surge remains unclear, experts said. The Northeast last year followed closely on Europe’s heels, but this time around has the advantage of better vaccination rates.
Europe’s vaccination effort has suffered greatly from disjointed distribution and procurement that relies heavily on the AstraZeneca vaccine, the use of which was briefly suspended in some bloc countries over concerns it might increase the risk of blood clots. The region also is under threat of the alarmingly contagious B.1.1.7 variant, first detected in England in December and now likely responsible for the bulk of cases in Europe.
Even if a new wave of infections does hit Massachusetts, it will likely be less deadly than it would be without vaccination, experts note.
“I think one of the huge saving graces of where we are right now is that so many of the highest-risk people have been vaccinated,” Jha said. “So what I don’t expect is kind of getting crushed on hospitalizations and massive increases in death.”
People under 29 have accounted for an increasing share of Massachusetts’ new COVID-19 cases in recent weeks, state data shows. A recent study published in Science that analyzed the trends of more than 10 million Americans attributed those age 20 to 49 with driving the fall resurgence of COVID-19 in communities. Still, Massachusetts has leaned more heavily than some states toward prioritizing older adults over the general population, meaning fewer of the state’s younger residents have been vaccinated. While this strategy helps reduce hospitalizations and deaths, experts said it does little to rein in the virus’s spread.
“We are restricting vaccines largely to a particular age group and that’s just going to have diminishing returns after a while,” said Jennifer Nuzzo, a Johns Hopkins University epidemiologist. “Drivers of transmission tend to be the 20-to-40-year-old range, so if we want to have a bigger dent on transmission, we need to start vaccinating those groups.”
(According to weekly numbers from the Massachusetts Department of Public Health, over 525,000 residents 20-49 have received at least one dose of the vaccine.)
While a less-deadly surge would be progress, experts warn against returning to normalcy before the vaccine is more widely administered. Millions more Massachusetts residents are set to become eligible over the next month, but the federal supply remains too low to inoculate every eager person immediately. Still, Baker announced the state would advance to Phase 4, Step 1 on Monday, ushering in an increase in the gathering limits for indoor venues to 100 people. The state will also soften its guidelines on out-of-state visitors, downgrading the existing travel order to an advisory. In response, a coalition of public health professionals issued an open letter to Baker on Thursday urging him to delay increasing indoor capacity limits at certain businesses.
“The current level of cases are unacceptably high,” said Samuel Scarpino, a Northeastern University epidemiologist. “We can see that the hospitalizations have come down because of vaccination. But there are still people getting hospitalized, there are still lots of people getting sick.”
With vaccinations ramping up and warmer weather on the horizon, Massachusetts could have hunkered down for a few more weeks and brought infections down to much safer levels, Scarpino and others said. The highest-risk people in the state could be vaccinated by the end of April, a milestone experts said was well worth waiting for.
“If we had just taken the measures that were working and left them in place for a little bit longer, we wouldn’t be having this conversation right now,” Scarpino said. “The cases would be continuing to drop week on week.”
The temptation to return to normal life is understandable, said Jenkins, the BU epidemiologist. But we cannot afford to let down our guard just yet.
“I think we can probably look forward to a reasonably enjoyable summer. But to do that, I really think we need to kind of sit tight for another few weeks,” Jenkins said. “This is a time for being cautious. The end is in sight.”
Dasia Moore is the Globe Magazine's staff writer. E-mail her at email@example.com. Follow her on Twitter @daijmoore. Hanna Krueger can be reached at firstname.lastname@example.org. Follow her on Twitter @hannaskrueger.