(NewsNation) — Wearing a mask is increasingly a matter of personal preference rather than policy, and while some are eager to ditch face coverings altogether, others have vowed to continue wearing them.

The national mask mandate for travel was lifted Monday (though that decision is being appealed) and other requirements have eroded as the pandemic stretches into its third year.

History and more than two years of the COVID-19 pandemic have introduced myriad approaches to curbing the spread of highly contagious viruses.

NewsNation spoke with experts to break down what the pandemic has taught the U.S. so far, and how that information can help inform future decisions about personal health and safety choices.

“Communitywide spread COVID is not happening everywhere and so masks aren’t necessary to be worn everywhere,” said Enbal Shacham, a behavioral science and health education professor at St. Louis University. “But when you’re thinking about public transportation or national and international travel, you’re going to have a higher risk of infection, just because we don’t know where everyone’s living and that space is all combined when we traveled together.”

Should you still wear a mask?

An ideal approach to safeguarding against COVID-19 would include a regiment of vaccines, boosters and masking, said Neysa Ernst, nurse manager of the biocontainment unit at Johns Hopkins Hospital.

Before going to a gathering, people should consider how many people will be present, if they’re vaccinated, and if anyone is ill, Ernst said.

“This is where you have to say, what’s the common sense move? Am I in a crowded environment, and there’s a chance for being exposed to a lot of sick people, COVID or not?” Ernst said.

The Center for Disease Control and Prevention’s website also features a COVID-19 tracker that uses data to help communities on a county-level decide what preventative steps to take depending on case numbers.

Based on the data experts have found while assessing the risk of transmission, people are least protected when no one is wearing a mask and somewhat protected when only one or some people are masked. The most protection exists when everyone wears a mask.

“The science says that when people wear masks, there’s less infection, especially when more people wear masks,” Shacham said.

Which mask works best?

The science is clear: any mask that fits properly and covers the nose and mouth will guard against infection to some degree, Ernst said.

A proper fit is key and although not all masks provide equal protection, any mask is better than none, Ernst said.

“A good, quality health care surgical mask will protect you and that’s especially important if you have any underlying chronic illness or you’re immunocompromised,” she said.

The CDC ranks common face coverings in the following order from most to least protective:

• Well-fitting NIOSH-approved respirators and N95s
• Well-fitting, disposable surgical masks and KN95s
• Layered, finely woven products
• Loosely woven cloth products

Face coverings don’t only protect against the virus that causes COVID-19, either.

“When we started masking and pushing flu vaccines and pushing COVID vaccines, our influenza admissions dropped dramatically,” Ernst said.

What have we learned?

The debate over masks isn’t new. It has roots in even centuries-old public health crises and underscores the effectiveness of simple precautions, Ernst said.

“Times change. People don’t … Hand hygiene is really important. Infection spreads through points of contact. So cover your nose and your mouth, especially if you’re sick,” Ernst said. “Every day, there’s a new variant in the in the paper. I think COVID is getting to the point was where we need to learn to live with it. We need to get our vaccines, we need to be vigilant. If we have underlying issues, we should be masking.”

Throughout the pandemic, health care officials have made strides in promoting protective behavior, and are doing more to reach underserved and disproportionately affected communities, she said.

“What we’ve learned, I think, is some better responses to protect ourselves from respiratory illnesses,” Ernst said.