Public health experts urge socially distant Fourth of July celebrations, as the coronavirus surges across the U.S.

Some communities are being preemptive: Los Angeles and Miami closed their beaches, New York City is shooting off “unannounced displays” of fireworks, so people won’t gather for a planned show. In cities from Anchorage to El Paso to Bloomington, Ind., forget about the parade.

But whether and how much the Fourth of July weekend boosts transmission of Covid-19 depends in no small part on the choices and actions of individual people. So health officials, clinicians, and infectious disease experts are pleading with the public to take precautions and minimize the risk that they might unknowingly spread the coronavirus or put themselves in a position to contract it.

“I do appreciate the fact that people are tired of being locked inside their homes,” said Monica Bharel, Massachusetts’ public health commissioner. But, she added, “this pandemic is far from over. We must continue to stay vigilant.”

There are no new strategies in their messages. Rather, as the country this week hit a record of more than 50,000 confirmed infections one day, they are stressing that people have a responsibility to protect themselves and others, and that actions like mask wearing, keeping distance from others, staying home if feeling unwell at all, and hand hygiene can make a significant impact.

They’re reupping their recommendations ahead of a weekend that could draw lots of people together and send some traveling to other states. The fear is that the virus could piggyback on those people, seeding new outbreaks in communities that right now are being spared from the U.S. epidemic or adding fuel to the fire in places experiencing transmission.

“These are anything but normal times, and a typical Fourth of July celebration could further spread the virus, endanger lives, overwhelm our health system, and undo the progress made toward reopening sectors of our economy,” read a joint statement from the leaders of the American Medical Association, the Association of State and Territorial Health Officials, and the National Association of County and City Health Officials.

“Without a safe and effective vaccine or therapy, our only option is to continue taking these precautionary measures to protect ourselves, our communities, and the most vulnerable among us,” the statement said.

Not everyone is being so cautious. President Trump and first lady Melania Trump on Friday will be heading to Mount Rushmore for a fireworks celebration, where masks will be handed out if people want to wear them but physical distancing will not be enforced, South Dakota Gov. Kristi Noem told Fox News.

By now, the steps to reduce the risk of spread should be familiar: It’s safest to socialize just with people in your household, and if you are going to meet with others, limit the number of people, stay outside, and keep your distance. Experts advise people bring their own food and drinks to cookouts, even “bring your own sunscreen, bring your own bug spray,” said Joshua Barocas, an infectious disease doctor at Boston Medical Center.

And if people aren’t going to stay at home, “I would recommend that people strongly consider staying local” rather than traveling far, said Rachel Levine, Pennsylvania’s health secretary.

Health experts also stressed that people with Covid-19 are contagious before they start feeling sick, so people shouldn’t think they’re safe to be around others if they’re feeling well. A study from the Centers for Disease Control and Prevention published this week found that fewer than half of 350 people who had Covid-19 reported knowing that they had been in contact with someone with the virus soon before their infection, indicating that people who do not think they’re at risk for contracting the virus still are.

The holiday weekend arrives as more states are reporting more cases and the U.S. epidemic reaches new levels of confirmed infections. Hospitals in the county’s South and West are warning about capacity limits; on Thursday, Houston Methodist took out ads in the Houston Chronicle urging people to “stay at home this July 4^th weekend.”

Officials have also grown alarmed by, they say, young people who are flouting distancing recommendations and packing into bars, leading to a bulk of new cases in some places in people in their 20s and 30s. Although young people are less susceptible to a severe Covid-19 case than older people, some will still get very sick and die. Plus, if the virus circulates at higher rates in any population, it has a better chance of infecting vulnerable people as well.

A growing number of states have closed down bars or limited their activity in the past week to prevent people from gathering.

Part of the nervousness around the holiday weekend stems from the thought that gatherings around Memorial Day helped ignite the major outbreaks that are flooding some communities. But experts say it’s hard to look back and tease out exactly what led to the spike of cases. Memorial Day also coincided with the reopening of businesses and activities in many states, so it’s possible the lifting of lockdown restrictions was more impactful than people coming together over a holiday weekend.

“With any single point in time, it’s difficult to attribute a surge to one activity,” said Marc Lipsitch, an epidemiologist at Harvard’s T.H. Chan School of Public Health.

Experts pointed to the fact that most Fourth of July activities will take place outside as one silver lining. The virus transmits much less efficiently outdoors than in enclosed spaces with little airflow.

But with more virus circulating now than over Memorial Day in many places, the risk of the same activities is much higher. Arkansas now has three times the cases it did in May, meaning that there is a greater chance of someone showing up to a celebration with the virus, said Nate Smith, the state’s health secretary.

“We need to be more vigilant this time than we were over Memorial Day,” Smith said.