Honolulu Mayor Kirk Caldwell is urging Oahu residents to wear a mask every time they go out in public to stop the rapid spread of the new coronavirus on the densely populated island with the vast majority of Hawaii’s cases.

“This enemy is invisible but we know it’s out there. It’s simple as this: You should assume you have COVID-19, and you should assume everyone around you has COVID-19. So when you put on the mask, you’re protecting others from maybe getting something you may have, and you’re also protecting yourself,” Caldwell said Thursday at a news conference after the state reported its second coronavirus-related death.

The mayor clarified that he isn’t asking residents to wear surgical or N95 masks that are reserved for health care workers on the front lines.

“In fact, we’re saying don’t use those masks. Those are to protect our medical professionals and our first responders, and there’s a shortage and we need to make sure there’s sufficient numbers for firefighters and everyone else who’s being called to help people who may be sick,” he said, adding that residents should use other masks like those made of cloth that can be homemade or purchased.

“The point is to wear a mask. It doesn’t give you 100% protection,” he said, but it could prevent people from touching their faces. “There are folks who are asymptomatic. You have COVID-19, but you don’t even know it and you could be contagious, and when you cough or breath on someone, you could transmit the virus. So the mask protects that person that you’re around, but it also protects you.”

Gov. David Ige told the Honolulu Star-Advertiser that he also supports the use of masks as long as people already have them and are not buying up limited supplies of surgical and N95 masks. Lt. Gov. Josh Green has also implored residents to routinely mask up when out in public, particularly if they are sick.

The Centers for Disease Control and Prevention and White House are also expected to soon come out in favor of wearing masks due to new evidence suggesting that people without symptoms may be unknowingly spreading the virus. Federal and state authorities have previously said there was no need for healthy people to wear masks, only those who are ill.

Ige reported Thursday the second COVID-19 death in Hawaii: an Oahu woman who was hospitalized after contracting the disease. An older Oahu man with preexisting medical conditions died Monday, becoming the state’s first fatality. The statewide total of COVID-19 cases has risen to 285, up 27 from Wednesday, which saw a record increase in coronavirus cases of 34.

State officials expect more cases over the next month, despite travel restrictions and other measures implemented to stem the tide of the disease.

“Sadly, I think there’s going to be more,” Caldwell said. “This is a life-and-death matter, and we need to make sure we’re being careful in everything that we do. We are seeing a large number of cases, and we think that we’re going to continue to see that because of the testing that’s ongoing. But, if we do the right thing, folks, we could see this spike start to level off. We could flatten that curve, giving our medical profession a chance to be ready and maybe never have to make a hard decision about who lives and who dies because we run out of ICU rooms or ventilators.”

Darragh O’Carroll, an emergency room doctor at Kuakini Medical Center, said days before even having symptoms, people might be shedding the virus in the community. The CDC has said up to 25% of people will not exhibit any symptoms.

O’Carroll advises people to sterilize reusable masks after each use, washing with soap and hot water and using a dryer or the sun’s UV light to kill germs.

“This is not a cure-all … but it’s gonna help to flatten the curve,” he said. “It’s not meant to give you a false sense of security that if you’re wearing a mask I now can talk to my friends and now can go socialize.”

Also Thursday, two confirmed cases of COVID-19 were reported at the University of Hawaii: a UH-Maui College employee last on campus Monday to pick up personal items, and a UH-Manoa graduate student on March 14. Molokai also had its first COVID-19 case, an adult male who recently traveled to Las Vegas.

Of all the confirmed cases in Hawaii since the start of the outbreak, 15 have required hospitalizations: 14 on Oahu and one on Kauai. A total of 72 patients have recovered since the start of the outbreak.

“It doesn’t mean because you get COVID-19 you’re gonna die,” Caldwell said. “But I can promise you if you don’t take the actions we’re requesting, more people will die, and one could be your loved one. We are at war. We can win this war, (and) with time we can see a flattening of that curve; and that is dependent on all of us doing what we’ve been asking all of you to do.”