The number of new coronavirus cases reported daily in Maryland’s Washington County is five times higher than it was at the start of the month, and the test positivity rate there now tops 8 percent, prompting county health officials to issue a public warning that there is “significant community spread due to gatherings of all sizes.”

It is against that backdrop that 1,200 runners will arrive this weekend to compete in the JFK 50 Mile, the nation’s oldest ultramarathon taking place amid 2020’s biggest headache.

Race organizers revamped protocols and instituted a variety of measures aimed at making the event safe, but public health officials warn that staging a race now poses unnecessary risks for both competitors and residents.

“I know it is hard to cancel an event that takes so much time and effort to prepare, but this doesn’t seem to be the best time to hold such an event,” said Maria Valeria Fabre, an assistant professor at the Johns Hopkins University School of Medicine who specializes in infectious diseases. “We know a lot more now than we knew in March about how covid-19 is transmitted, and we know that people gathering in this way is a major factor in transmission.”

The event website noted that organizers “have every intention” of holding the race Saturday. Mike Spinnler, the race’s longtime director, did not return several messages seeking comment this week, nor did Earl Stoner, the county health officer. A Washington County spokesperson deferred questions to the event’s organizers.

First run in 1963, the JFK 50 Mile is a bucket-list race for many endurance athletes and is among the few top-tier U.S. racing events that haven’t been postponed or canceled by the pandemic. The race takes runners from Boonsboro to Williamsport, a horseshoe route winding along the West Virginia border and covering terrain from the Appalachian Trail to the Chesapeake & Ohio Canal towpath.

It cuts through the heart of a region that has produced some of Maryland’s highest case rates of late. While the entire state has been experiencing a surge in recent weeks, nowhere is the spike more precipitous than Western Maryland. Though Washington County’s numbers aren’t as bad as those of nearby Allegany and Garrett counties, it’s still seeing more per capita infections and hospitalizations than ever.

“I think certain people out there had a false sense of security that: ‘Oh, that’s, you know, it’s very concerning. But I don’t have to worry about that because I live out here in this rural neighborhood,’ ” Gov. Larry Hogan (R) said at a Tuesday news conference.

Hogan tightened restrictions across Maryland this week, barring spectators from racetracks and football games. The state had previously given a green light to organizers of the JFK 50 Mile race, though that approval came before the recent rise in cases. Michael Ricci, a Hogan spokesman, said the event doesn’t contradict the governor’s latest orders.

State police and the National Park Service have been in touch this week with race officials, reminding them about the statewide restrictions and Maryland’s travel advisory. Race organizers sent an email late Wednesday to registered runners, informing them of new travel restrictions. Organizers now say that any out-of-state runners traveling to Washington County will need to take a coronavirus test “promptly upon arrival in Maryland or within 72 hours before travel to Maryland.”

The 1,200 runners will be sent off in waves of 250, which is the state’s current limit on outdoor gatherings, and masks will be given to every participant. But that 250 figure does not appear to account for race officials, volunteers or spectators. And public health experts say that even if organizers take every precaution, there are no ways around some of the inherent risks.

For starters, the race draws runners from all over, inviting them into small Western Maryland towns, many staying in hotels, shopping in local stores and eating in restaurants, before sending them back to their home communities. A review of more than 950 finishers from last year’s JFK 50 Mile race found competitors hailed from 39 states plus D.C., Puerto Rico and at least four other countries.

“It’s exactly what we’re recommending against: people traveling, coming together in groups, dispersing back to their communities,” said Shmuel Shoham, an associate professor of medicine at Johns Hopkins who specializes in infectious diseases. “Even in waves, if you’re going to have 250 people coming from all over the place, there’s a very high chance at least one would be an asymptomatic carrier.”

Shoham is a runner himself, and he has finished the JFK 50 Mile race. He is sitting out this year. “If we didn’t have as much community transmission, things were quiet, back where we were in the summer, I would feel a lot better,” he said. “But not the way conditions are right now.”

The number of coronavirus-related hospitalizations in Washington County has never been higher and is more than double what it was during the initial spring surge. In issuing its public health alert last week, Washington County officials urged people to “consider canceling or postponing gatherings that are not essential” and said: “Our big problem with covid-19 is once it starts picking up steam, it’s really hard to stop it. Washington County is at a dangerous point in this pandemic.” Neither Jeffrey Cline, the board of county commissioners president, nor Kirk Downey, the county administrator, returned messages this week seeking comment.

“We are at a critical point, and now is not the time to reduce our vigilance, or reduce protective measures put in place,” Stoner, the county health officer, said in a news release.

Organizers made several changes to the event and last month unveiled a 19-point safety plan. There will be no awards ceremony, no access to the schools where the race starts and finishes and no shuttle service to and from parking lots. And organizers “will not tolerate activities that are dangerous,” which includes “spitting or droplet-generating activities, such as coughing or sneezing without properly covering mouth and nose.”

The 250-person waves will not be allowed to overlap in Boonsboro at the same time, and even at the starting line, runners will be required to remain six feet apart. Runners will be expected to cover their faces at the start of the race and whenever they’re grouped with other runners on the course.

The event did not initially require testing or quarantining, and it still permits spectators at the start and finish lines.

Even if these protocols are adhered to, Fabre said, they may not work. She said masks that get wet, either from water or sweat, are less effective than dry face coverings. And she said air particles emitted during strenuous activity can travel farther.

“Even if you try to remind people what not to do, maintaining those six feet of distance or wearing your mask, it is hard for people to be entirely compliant, especially when they’re doing exercise,” she said.

Even if runners are experiencing mild symptoms, Shoham said, ultramarathoners tend to run through pain or illness and “could be in denial about what’s going on.” After running for upward of eight or nine hours, their judgment could be compromised, and many could become lax in their precautions on the course. And, he pointed out, trail races tend to be social events, with runners often grouped together. Even on the course, where the trail narrows, the line of racers backs up behind a slower runner and bunches together at choke-points.

The event’s website as of Friday afternoon said only 12 of the 1,200 spots in the race field remained available. It made no mention of possible refunds and said registration fees would be deferred to a future race in the event of cancellation.

Kyle Herrig signed up for the event in the summer when coronavirus numbers in the region were much lower. With a couple of marathons and a handful of half-marathons under his belt, he was eager to tackle his first ultramarathon. The JFK 50 Mile race was one of the few options available.

“I ultimately made the call to withdraw from the race,” he said. “It seemed selfish to me to engage in nonessential travel to the race and potentially put myself and others at risk of spreading covid.”

There will be no trophy or results list to record his effort, but Herrig plans to instead run 50 miles this weekend by himself near his New York home.

“And that’s part of what I don’t understand,” he said. “People would probably be bummed if they canceled, but you can still do the underlying activity on your own.”

Erin Cox contributed to this report.