Coronavirus has claimed more than 100,000 US lives. And the first wave isn’t even over yet.

Follow all of PopSci’s COVID-19 coverage here, including tips on cleaning groceries, ways to tell if your symptoms are just allergies, and a tutorial on making your own mask.

The US now accounts for close to 30 percent of reported COVID-19 deaths across the world. First identified in Wuhan, China, in December, the novel coronavirus claimed its first life in the States on February 29 in Kirkland, Washington. Three months later, the disease has touched nearly every part of the country, with cases still rising sharply in many states. Last night, on Wednesday, May 27, the US death toll crossed the 100,000 mark. The confirmed case count also jumped to close to 1.7 million.

While cases are leveling out or even declining in several states—including New York, New Jersey, and Michigan, which were previously major hotspots for the novel coronavirus—daily diagnoses are on the rise in Alabama, Florida, California, Puerto Rico, Louisiana, North Carolina, Wisconsin, Mississippi, South Carolina, Arkansas, Nevada, Idaho, North Dakota, Maine, West Virginia, Vermont, Wyoming, and Alaska, according to tracking by The New York Times.

But even as COVID-19 spreads, some states are moving to loosen their restrictions on businesses and encouraging people to leave their homes. Here’s everything you need to know.

What is COVID-19?

COVID-19 is the disease caused by a novel strain of coronavirus. Common symptoms include fever, shortness of breath, a dry cough, chills, muscle pain, sore throat, and loss of taste or smell. Symptoms are mild in the vast majority of cases, and even asymptomatic carriers can be contagious. This is part of why COVID-19 is spreading so prolifically: The CDC reports that as many of 35 percent of contagious COVID-19 carriers may feel totally fine. These individuals likely infected others with the disease while carrying out normal activities like working, shopping, and socializing without keeping proper distance.

While COVID-19 is mild for most, the virus can lead to severe pneumonia, heart failure, and other fatal complications. Some patients’ oxygen levels drop to dangerously low levels before they even feel short of breath.

Serious symptoms are most common in those over the age of 60, as well as in people with underlying health problems. But hospitals around the world are also reporting life-threatening cases in young, otherwise healthy patients. There’s now evidence that COVID-19 can cause deadly strokes in healthy young people, some of whom never experience serious respiratory symptoms. And while COVID-19 seems to largely spare young children, doctors have now identified at least 102 cases of a dangerous inflammatory response to the virus in kids. Though more data is needed to be certain of the connection between this condition, which can lead to cardiovascular problems, and COVID-19, it appears to be triggered by the body’s immune response to the virus in some individuals.

How serious is COVID-19 in the US?

As of May 28, the US had far more confirmed COVID-19 cases than anywhere else in the world. Tracking by Johns Hopkins University puts the nation’s known case count at more than 1,699,933. Because research has shown that the vast majority of people with COVID-19 show minimal symptoms (or none at all), it’s likely that the actual number of cases in the US is much higher. There have been at least 100,442 deaths attributed to COVID-19 in the US so far—but many more have likely gone uncounted, due to the myriad of conditions that people are dying from. While cases are starting to level off or decline in some of the areas earliest hit hard by the pandemic, like New York City, Detroit, and New Orleans, confirmed infections are still ramping up in other states.

“Even though we call it a pandemic, it’s really multiple hundreds of different outbreaks in the US going on at the same time,” Ali Khan, former director of the Office of Public Health Preparedness and Response at the Centers for Disease Control and Prevention, told NPR. “A lot of separate outbreaks will feel like sort of a second wave coming.”

Current projections suggest that if most Americans stay home and avoid contact with others, the worst of the country’s first wave of COVID-19 will pass by early summer. See when your state is projected to see the most cases.

Do we still need to stay at home?

Yes. Everyone should be practicing social distancing to limit the spread of COVID-19 and flatten the curve. Even people who live outside the current hotspots for the disease should stay home as much as possible.

Ideally, you should remain at least six feet away from all other people. Maintaining contact with your family members is okay as long as you’re all doing your best to avoid getting close to individuals outside the household. Even if you don’t have symptoms, spending as much time isolated as possible means you’re lowering the risk that you will catch and spread COVID-19 to someone vulnerable.

Implementing preventative social-distancing measures will reduce the number of people who are sick at one time. Without such measures, many people get sick all at once, leading to a tall, narrow curve of cases and hospitalizations. Social distancing can flatten the curve so that even if just as many people may get sick overall, they’ll be spread out over time. For a health care system, especially an overwhelmed one, it’s far better to have two or three million people sick over the course of a year than have that same amount of patients sick in the span of three months. Hospitals running over capacity simply aren’t able to provide life-saving care to everyone, which leads to more deaths.

The Washington Post has an excellent interactive graphic to demonstrate the importance of social distancing, if you don’t understand why it’s important.

When will it be safe for things to reopen?

The White House has said that areas should begin to reopen when their case numbers steadily decline for at least 14 days. But reopening should not happen at the flip of a switch. For example, experts say bars and restaurants may need to operate at only half capacity until a vaccine is available, while retail spaces may be able to do business safely if they limit customers and take other precautions, such as requiring masks and gloves.

Take California for instance. The state is slowly reopening businesses due to the sustained slowdown of new COVID-19 cases. Two months after implementing strict shutdown and social distancing measures, it’s following a four-part reopening plan that will allow less-affected areas and those that meet certain testing requirements to open more businesses sooner. Bars and restaurants remain closed, with the process marking “a slow and gradual change to a new reality” instead of a sudden return to normalcy, according to LA officials.

In contrast, several states where COVID-19 cases are still on the rise—including Florida and Texas—have reopened potentially dangerous commercial spaces such as gyms and restaurants. New York and New Jersey, on the other hand, have acted cautiously, allowing for a few parks, beaches, and businesses to reopen over Memorial Day Weekend.

The Centers for Disease Control and Prevention (CDC) recently compiled a comprehensive guide to the gradual reopening of businesses across the country, but the Trump Administration has rejected it for being “overly prescriptive,” according to reporting by The New York Times. The plan suggested placing limits on many businesses and organizations that would continue to slow the economy.

Several states have seen anti-lockdown protests in recent weeks, where crowds gathered in close proximity—sometimes seeking to block traffic on roads near hospitals—to oppose curfews and business shutdowns. According to a recent poll by the Pew Research Center, 68 percent of all Americans surveyed are more concerned about lifting restrictions on public gatherings too quickly than they are about continuing to social distance. Another poll by the Associated Press found that 76 percent of Americans surveyed supported keeping bars and restaurants closed. Even more responded positively about stay-at-home orders and limits on public gatherings.

How serious is COVID-19 globally?

Close to six million people have been diagnosed with COVID-19 worldwide in at least 188 countries, affecting every continent save for Antarctica. At least 356,213 people have died so far. While cases are finally on the decline in severely affected countries like Spain, Italy, and Germany—and have long been negligible in China, where the virus that causes COVID-19 originated in December—cases are holding steady in many countries, and still increasing in dozens of nations like India and Brazil.

South Korea, which quickly contained an outbreak earlier this year by testing a huge percentage of its population, provided a grim case study for other countries earlier in May. Officials linked more than a 100 new COVID-19 cases to a single young man who visited three nightclubs in Seoul and then tested positive for the virus. They expect more cases related to his bar-hopping to emerge, and have contact traced and tested a reported 46,000 individuals. The country also just began reopening schools this week.

What can I do to prevent the spread of COVID-19?

Proper hand washing (instructions here) is still the best defense we have against a disease like COVID-19. Hand sanitizer is less effective, but it’s a good substitute in a pinch—here’s a DIY recipe if your local stores are sold out.

While the evidence for the efficacy of face masks remains murky, the CDC now recommends that everyone in the US wear them when leaving the house. The hope is that this low-cost, low-risk intervention—when implemented en masse—will help cut down disease spread from asymptomatic carriers of COVID-19. Here’s a guide to buying or making a mask with whatever material you’ve got. And here are instructions on how to effectively sanitize your cloth masks.

It is also important to practice social distancing if you’re able, even if your area hasn’t been hit by a big outbreak or has started reopening after one, and to be diligent about washing your hands if you have to go out and interact with people. Don’t go to bars or restaurants; having takeout delivered is the best way to get food from your favorite local business (you should, of course, tip even more generously than usual).

Trips outside the home should be limited to isolated exercise (jogging by yourself in an area without crowds, for example), taking walks in areas where you can keep your distance from others, and getting essential medicine and groceries. You should clean your hands frequently and avoid touching your face while out conducting essential errands.

It’s possible to help people working on the front lines, even while limiting your time outside your home. Find out if you have any supplies you can donate to your local hospital here.

When will there be a treatment or vaccine for COVID-19?

The Food and Drug Administration has officially given the Ebola drug remdesivir emergency approval as a COVID-19 treatment, but there’s still only limited evidence that the medication can help. Doctors are continuing to try other potential therapies in hospitals, but some some worry this will negatively impact patient recovery.

The most promising timeline for a COVID-19 vaccine came recently from Oxford University, where researchers have stated that their treatment could be ready by this coming fall. Still, it would take many more months for it to be approved and prepared for widespread use. Massachusetts-based company Moderna also released positive results from its clinical trials, which began back in April. Scientists, however, are skeptical because the data left out the reactions of nearly half the participants.