MIAMI (AFP) - They are itching for a good time after months of lockdown, coronavirus be damned: young adults in Florida are fuelling a dangerous rise in Covid-19 infections.

Seemingly feeling immortal, these fun-crazed people began gathering in bars, nightclubs and elsewhere after the Sunshine State reopened its economy this month - though the state has now had to put a hold on alcohol-fuelled nightlife.

Check out Instagram, and there's always a party on a beach somewhere, or at a swimming pool, or on a rented yacht in south Florida, where nightlife spots other than restaurants are still closed.

Plus, buses are hired for bachelorette parties teeming with folks drinking beer, dancing to reggaeton music - and spreading the coronavirus.

Infection rates were stable as Florida joined the rest of America in lockdown from March through May. But they shot up in June after the state moved to reopen and tourists from all over the country started pouring in.

On Ocean Drive, which is a kind of party central in Miami Beach, visitors from Missouri, Texas, Georgia and elsewhere stroll by the sea.

Round about midnight Mike Olivera, a 25-year-old visiting from New York, sits on a wall on the oceanfront promenade and sneaks sips of vodka with a buddy, watching a steady flow of fresh-faced young humanity saunter by.

And listen to how concerned Olivera is about mask-wearing and social distancing: "I wanted to get laid," he said, explaining why he came to Miami.

Olivera chuckles, then clarifies. He is from New York, the former Covid epicentre of America, with its tight social distancing restrictions.

"So I wanted a break and actually to be able to do things, meet nice people and hang out," said Olivera.

With that kind of attitude common, Florida has set records for new cases almost every day for the past two weeks - more than 5,000 on Wednesday and Thursday as infection rates rise ominously here and elsewhere in the South and West of the country.

On Monday, Florida surpassed 100,000 known coronavirus cases, and the average age of the people infected is now 33 - down from 65 two months ago.

Governor Ron DeSantis said this week the state is seeing a "real explosion" of virus cases among young people, and he warned that places serving booze without enforcing social distancing rules could be stripped of their liquor licenses.

On Friday, the state abruptly halted on-site alcohol consumption in bars because of the surging infection rate.

Dr Anthony Fauci, the nation's leading infectious disease expert, said young people nationwide, many of them asymptomatic and spreading the virus unknowingly, are now driving a "paradigm shift" in the dynamics of the pandemic.

In stern terms, he warned them to think about the health of others.

"If you get infected you will infect someone else," he told a news briefing after a meeting of the national coronavirus task force, the first in two months.

"And then ultimately you'll infect someone who's vulnerable.

"The only way we're going to end it is by ending it together."

In Florida, servers braving crushing heat sweat through their face masks and wear plastic gloves as they wait on customers.

Some restaurants have been shut down or closed voluntarily to try to contain the spread of the virus in a state heavily dependent on tourism revenue.

LIFE IS NOT NORMAL

Olivera shrugs off the threat of the virus.

"No, I don't feel like it's going to affect me. I'm 25 years old, I don't feel like I have anything to worry about," he said.

"I faced uglier things. I come from the Bronx, you know what I mean. If I survived that I can survive Miami," he said, then downed a shot of vodka.

But Annalisa Torres, a data analyst newly graduated from the University of Florida, said it irks her to see people her age behave this way.

"It's important to recognise that as young adults, the actions we take throughout this pandemic don't only affect us, but the people around us," she said from self-quarantine in her home in Miami.

"In my case, I live with my parents and younger brother. I stay home not for me, but for them," said Torres.

The problem is that when young people are told they are less vulnerable to the coronavirus they feel impervious to it, said Mary Jo Trepka, an epidemiologist at Florida International University.

"The message has been that it's primarily severe for older people, and that young people are less likely to get sick," she told AFP.

"That's very true, but once you start getting so many young people that are sick, there will be some that are going to get very sick and will end up being hospitalised," Trepka added.

And many families in south Florida are multi-generational, so younger people are often in contact with elderly relatives at home, she added.