Two weeks ago, for the first time in a year, I intentionally walked out of my front door without a mask. I didn’t even have one in my pocket. I have been vaccinated and was planning to be outdoors only, and so I was certain that going unmasked posed no risk to anyone. Still, the moment was eerie and profound. And not just because I had that phantom sense of having left the house without my keys, or my phone, or my pants.

Last spring, New York City was the global epicenter of the coronavirus pandemic. Well over 10,000 people are estimated to have died here before most states began to see any significant effects. Freezer trucks idled in Manhattan parking lots as morgues overflowed, and thousands of bodies were buried in mass graves. The trauma touched everyone personally, and most people in the city have since been extremely vigilant about masks.

Read: Excuse me if I’m not ready to unmask

So for those of us in New York City, the shift to going barefaced seems especially dramatic. I imagined that it would feel like a culminating event, a transition to an ending. Then about two blocks after leaving home unmasked—and after nearly a year and a half of treating my mask as an extension of myself—that sense evaporated. Walking around without a mask is, it turns out, like riding a bike: It’s exhilarating for the first minute, and then you just take it for granted, and your mind goes back to worrying about other things, such as trying not to get hit by cars.

This is a pivotal moment in the pandemic. So much of the year’s anxiety and confusion converges in our relationship to masks, which have come to be about far more than blocking aerosolized secretions. Mask mandates are being lifted around the country as cases of COVID-19 plummet. The all-encompassing threat of the pandemic suddenly feels like a blip on the national radar, thanks to a massive vaccination campaign and a deep-seated desire to talk about anything else at all. When the CDC advised two weeks ago that vaccinated people no longer need to wear masks, indoors or out, the change around New York City was nearly instantaneous. Nationally, the move correlated with a bump in vaccine demand.

For some, this is jarring, even scary—especially for those who have not yet gotten vaccinated, who have post-traumatic anxieties after life-threatening bouts with COVID-19, or who are at high risk of complications. The pandemic is not over, and the past year has seen a barrage of experts insisting that masks save lives. Wear a maskWear a maskWear a mask. Out in public, it’s impossible to know who’s been vaccinated. Many businesses have opted to continue requiring masks indoors, while others have not.

It is true, from a purely scientific perspective, that vaccinated people don’t seem to pose a meaningful risk to others, or to themselves, if they forgo a mask. We have not seen a terrible number of serious breakthrough cases, and vaccinated people do not seem to serve as asymptomatic spreaders of the disease. But real tensions exist between mask science and mask guidelines. From a guideline perspective, having different rules for vaccinated and unvaccinated people creates a minefield for public venues, businesses, and other institutions where employees have no way of distinguishing between who is and isn’t vaccinated. A school system may be able to verify the immune status of its students and faculty, but a restaurant or grocery store cannot sort everyone who comes through the door.

Read: Are outdoor mask mandates still necessary?

This has inspired heated debate and inflamed instincts to assign blame. Is the CDC being too vague, too progressive, or simply careless in its advice? Should local governments step in with clear directives? Are businesses supposed to decide for themselves and enforce rules however they choose? Do those decisions involve liability? Are we looking for definitive answers that don’t exist?

This gap between science and guidelines is not new; it’s a constant source of friction in public health. Take, for example, the recommendation that we exercise for 150 minutes a week, or that men limit themselves to two alcoholic drinks a day. These numbers are not divinely ordained. Exercising for an hour every day would likely be even better for our health, as would restricting alcohol intake to one or zero drinks, instead of two. But the guidelines are meant to consider what’s practical and actionable for people in a real-world context, as opposed to the pure dictates of ideal physiology or toxicology. If you advise people that teetotaling is the only true path, or that they need to spend every day in the gym, they may throw up their hands and do neither.

The same risk applies to mask guidelines. A purely scientific approach does not offer clarity, and it may leave many of us in an awkward position. There could be hundreds of pages of specific circumstances in which masks are or are not recommended, based on airflow patterns, the demographics of the people in proximity to you, local rates of transmission and vaccination, and so on. None of these variables is independent of the others. There’s no immediate way out of this uncertainty.

The acute phase of the pandemic provided a rare opportunity for simple messaging on masks and other interventions. First, the guideline was: Do not leave home. Later, it was: If you leave home, wear a mask. Emergencies have a way of focusing our attention on discrete tasks. Now that the threat is less, and half the country’s adults have been vaccinated,  simple guidelines have given way to riddles: If I’m outside at a party with 13 people but two of them are only partly vaccinated and two are not at all, and some of them go inside some of the time, and we are a choir but we don’t sing more than the first verse of a song, do I need a mask?

This ambiguity is a by-product of progress. Things are not going to get any clearer anytime soon—and let us hope that they don’t. Some degree of immunity will wane in the coming months, and the warm weather will fade; cases will continue to percolate, and then surge in certain places. The risk, at that point, will not likely warrant another lockdown—but it also can’t be entirely disregarded. As long as the pandemic persists, we will all need to be flexible and solicitous of those around us, and we will all need to wear a mask in certain situations. Anyone who feels more comfortable wearing a mask should absolutely continue to do so. Anyone who questions your choice and tries to explain to you that it’s unnecessary should be told that their explanation is unnecessary. When in doubt, wear one. Remember how much nicer it is to throw on your mask occasionally than it is to wear a mask everywhere you go.

Read: The Texas mask mystery

Masks may be recommended during “cold and flu and COVID-19 season” indefinitely. But guidelines change as situations do. The value of any preventive measure depends on where you are, and where the virus has been surging. Masks are just one of the tools in our kit of interventions. Like any tool, they are not simply good or bad, any more than a bandage or an EpiPen is good or bad. The value of the intervention depends entirely on when and how it’s used. Wearing a life jacket while you’re in a dinghy lost at sea is a great idea. Wearing a life jacket in your living room while watching Pirates of the Caribbean is a less valuable intervention. Likewise, as SARS-CoV-2 grows less ubiquitous, the value of a mask declines in step. As your community gets vaccinated, you can feel more and more comfortable in the knowledge that adding a mask will not add much benefit.

The same principle applies to the future. If SARS-CoV-2 surges again in the fall or winter—nationally or in specific states or counties—then the value of masks could rise again. You may end up being asked to wear a mask in one place but not another, even if you’re fully vaccinated. This wouldn’t be a contradiction or a flip-flop; it wouldn’t mean that experts can’t make up their mind and shouldn’t be trusted. It would mean that a sweeping mandate is the most effective mask guideline, in that moment, to beat back a resurgence. I hope that isn’t necessary in many situations, because I’m already extremely used to not wearing a mask. I hope this summer involves a lot more opportunities to leave home without one, to see faces without that constant reminder of this tragic year. But I’m also not about to throw out my stockpile.