New state guidances to wear masks in public and to limit the number of people in grocery stores were driven by "growing consensus" among experts that up to 20 to 40 percent of those infected with COVID-19 may not display symptoms and therefore could transmit the virus to others unaware, Gov. Charlie Baker said Saturday.

While hospitals race to prepare for a surge in cases expected to hit around April 20, Baker said the public must take every possible precaution to limit spread of the highly infectious coronavirus, especially now that the rate of asymptomatic illness could be "a much bigger number than was originally anticipated."

"There's a growing consensus about this particular virus that there is a minority population, but a significant portion of the population, who are not going to show symptoms," Baker said at a press conference. "They will be infected, they are carriers, but they're not going to show symptoms. Now, that's an almost impossible number to figure out until you get testing in some part of the world to a level way beyond where it is now, but the estimates range anywhere from 20 to 40 percent depending upon who you talk to."

The governor continued: "Part of the reason we decided to put the advisory out on masks or face coverings if you can't be in a situation or a circumstance where you can distance appropriately from other people is because of this issue of people who may be in fact infected but have no idea. This goes both ways. The point behind the face covering is not just about protecting yourself from somebody else, it's also about protecting somebody else from you if you happen to be one of those people who doesn't know you've been infected because you aren't showing any symptoms."

On Sunday, National Institute of Allergy and Infectious Diseases Director Dr. Anthony Fauci said at a White House press briefing that rough estimates indicate "25 to 50 percent" of those with the coronavirus infection may not dispaly symptoms.

The governor said the asymptomatic segment of the infected population could be significantly larger than previously believed.

"It's going to take a while for everybody to ultimately figure out, because again, we're dealing with a new virus, an unprecedented circumstance here, what the actual size of the infected but not symptomatic population is, but there's no question at this point, based on what a lot of the experts are saying, they think it's a much bigger number than was originally anticipated," he said.

He later said the emphasis on social distancing, good hygiene and now masks is critical "especially with some of this new knowledge coming out that implies significant portions of the population can in fact be infected, can in in fact be carriers, and show no symptoms."

The Baker administration said last week that its model predicted between 47,000 and 172,000 of the Bay State's nearly 6.9 million residents would contract the virus over the course of the outbreak.

Through Saturday, Massachusetts has 22,860 confirmed cases of COVID-19, according to the latest data from the Department of Public Health. Another 87 fatalities were reported Saturday, bringing the death toll to 686.

Total confirmed COVID-19 cases in Massachusetts rose to 22,860 on Saturday, while 686 Bay State residents have now died as a result of the virus. [Graphic: Chris Lisinski/SHNS]Modeling indicates that April is "probably going to be the toughest month for the people of Massachusetts," Baker said, defending the state's "draconian measures" shutting down non-essential businesses and urging residents to stay at home whenever possible.

"This is going to be a rough time, and I get the fact that it's a nice day, but people really need to accept the fact that this virus is insidious, in some cases is invisible, and it will prey on people if you give it the opportunity," he said. "The best way you can kill it is to not give it to someone else and not get it yourself."

Baker's reiterated warnings came following a tour of a new mask decontamination facility in Somerville, a program he described as a vital first step toward providing sufficient resources to health care workers.

The facility is modeled on similar setups deployed in Ohio, New York and Washington, officials said, and received emergency authorization from the Food and Drug Administration.

Once it is fully operational, the Battelle critical care decontamination site will be able to clean up to 80,000 used N95 masks per day. Partners HealthCare Chief Innovation Officer Chris Coburn said the facility can help meet what is a current need for 25,000 masks per week and a projected future need of 45,000 per week.

"The masks that come out of here have the same level of decontamination as masks that are purchased new from a manufacturer," he said.

Partners believes each mask can be used up to 20 times with cleanings in between each use, though Coburn noted five to 10 times per masks is a more likely outcome.

Under the structure of the current deal, the federal government will cover the costs and hospitals will not have to pay for decontamination services. Once that funding runs out, Baker said, health care providers can get masks cleaned for a lower price than purchasing them new.

Dr. Paul Biddinger, head of Massachusetts General Hospital's Division of Emergency Preparedness, said increasing the supply of N95 masks to health care workers is "absolutely essential" and touted Battelle's system as entirely effective at decontaminating both bacterial and viral sources.

"For so many weeks and now months, you've heard me say we cannot buy enough of the personal protective equipment that we'd like. It's just not there for purchase," Biddinger said. "In terms of expanding the available pool, not just within Partners HealthCare but for all the hospitals of the commonwealth that are reaching out to be part of this process, this really represents an opportunity to have more PPE for the front-line health care workers who need it in ways we just cannot purchase on the market, almost irrespective of price."

Baker, who praised Somerville Mayor Joseph Curtatone as having "moved heaven and earth" to get the facility approved, said the decontamination facility is an important step but will not, on its own, fulfill all of the state's needs.

Acquiring personal protective equipment and other key gear "remains one of the biggest challenges" of the COVID-19 era, Baker said. The governor expects another 200 ventilators to come from the national stockpile, which would bring the total Massachusetts received from that source to 400.

"The message we got from the feds was that we would be receiving ventilators on an incremental basis, and so far, they're living up to that," he said. "We're obviously going to continue to pursue the full 1,000 we believe we need. We're also pursuing a variety of private sector channels that I believe remain promising as well."

With Easter approaching and Passover underway, Baker asked those who will be practicing their faiths in the coming days to direct prayers toward those sick with COVID-19, their caretakers and their families.

Michael P. Norton contributed reporting.