The pandemic outlook in the U.S. continues to improve, with confirmed COVID-19 cases falling for the sixth consecutive week and deaths having declined for the past three weeks. But spring break is on the horizon, bringing with it a potential uptick in travel, which has public health experts concerned about the consequences if people don't remain vigilant.
Anxiety over spring break travel is rising after a particularly grim few months when case numbers, hospitalizations and deaths spiked dramatically after the end-of-year holiday season. And with several strains of the coronavirus circulating in the country — including some variants that are thought to be more transmissible — some experts worry that spring break getaways could threaten recent progress.
"Any event that involves increased travel and people relaxing preventative measures is a concern," said Amber D'Souza, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.
D'Souza said patterns that have emerged over the past year demonstrate how much the trajectory of the pandemic is driven by behavioral changes. For example, as places experience severe outbreaks, people typically respond by staying home, practicing social distancing and wearing masks. But as the situation improves and restrictions are rolled back, many tend to become more lax, which can cause new outbreaks to surge.
"This is exactly what we saw after Thanksgiving and after Christmas," she said. "It's an ongoing cycle and an ongoing concern."
Last March, the U.S. was only just beginning to emerge as the new center of the pandemic, and states have struggled to contain the virus's spread over the past year. On Sunday, the U.S. hit 500,000 deaths from COVID-19, eclipsing the death toll of every other country.
Although the numbers of cases, hospitalizations and deaths have been falling in recent weeks, the U.S. is still averaging more than 1,000 deaths every day from COVID-19.
"The rates have come down," D'Souza said, "but they're still not what we would consider low. We're just much better than where we were a month ago."
D'Souza said some spring break trips last year have led to local outbreaks, but the true impact of the spring travel may never be known because the data weren't tracked nationally. Florida Gov. Ron DeSantis, in particular, was heavily criticized for refusing to close beaches last March, even as the coronavirus was spreading in the state.
This year, some officials are enacting new restrictions ahead of spring break. Miami Beach is introducing a midnight curfew in the entertainment district, and alcohol is prohibited on the beach.
“If you’re coming here because you think it’s an anything-goes place, please turn around or go somewhere else,” Mayor Dan Gelber told WPLG-TV on Monday.
At the same time, U.S. airports report steady increases in passengers compared to last year, although the level of travel in the U.S. remains significantly lower overall.
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Clayton Reid, CEO of the travel marketing firm MMGY Global, said the rebound started last summer and is expected to continue.
"We're expecting a huge return to travel in the spring and summer," he said, adding that leisure travel, in particular, is likely to rise sharply once vaccinations are available to more of the population.
In the meantime, the Centers for Disease Control and Prevention has been advising Americans to avoid unnecessary travel.
But if people are intent on spring getaways, there are ways to reduce the risks, said Dr. Joseph Khabbaza, a pulmonary and critical care medicine specialist at the Cleveland Clinic.
"Across the board, driving somewhere else is always going to be safer than having to be in airports or bus terminals or riding trains with other people," he said.
Outdoor experiences, such as camping trips and visits to state or national parks, are also less risky, he said. But regardless of the destination, Khabbaza and D'Souza said, it's important to avoid large gatherings, wear masks and practice social distancing.
"You want to either be masked or find a place that is distanced," D'Souza said. "If you are sitting at a crowded bar with a lot of people around unmasked, that is definitely a potential source of transmission."
D'Souza said she recognized that people may be dealing with pandemic fatigue and are looking for an escape, especially as the weather warms, but she urged people to be cautious and weigh the risks.
"If people don't travel at all, that is the safest thing," she said. "But if people choose to travel, it's about being smart about it."
This story first appeared on NBCNews.com.