Dr Asma Rashid, who runs a members-only medical concierge service in the Hamptons, has received some of the most sought-after party invitations this summer. “We’ve gone to these private events, where they have me sign a ‘nothing you see in this house can be leaked’ document,” she said. “This is still a party town.”

Dr Rashid is there to administer rapid or real-time tests for coronavirus. She performs the procedure — either a finger prick or a nose swab — in the car, and then lets guests into the house only if their tests come back negative. The entire procedure takes less than 30 minutes. Consider it a pandemic pre-game. Suffolk County still lacks rapid testing infrastructure, and the private service is expensive: up to $500 per test, and not all insurance companies will cover the cost. Most doctors don’t even have kits to do the tests; patients willing to pay can wait up to a week for an appointment at the offices that have them in New York City. For that reason many clients book Dr Rashid in advance when they anticipate hosting guests for a sleepover, a barbecue or a wedding. But some summon her at 2 am for a last-minute test or stop by her office in a panic after attending a crowded gathering.

“Every time there is an event, a protest or Fourth of July celebration, there is higher demand,” she said. A busy day came after a drive-in “Safe & Sound” concert, where the chief executive of Goldman Sachs performed, at the end of July. Concert-goers, who paid $1,250 per car to attend, were supposed to stay in their cars, but social media showed crowds dancing by the stage. “I can’t even tell you how many requests we got after that,” Dr Rashid said.

The event is currently under investigation. Dr Rashid has tripled her staff to keep up with demand for coronavirus testing this summer. The last Saturday in July she even opened a new office in Bridgehampton. “The way I would describe our growth is exponential,” she said. While most of the country waits seven to 14 days for coronavirus test results, a privileged few have access to rapid tests. There are a few types — some detect antibodies, others antigens or viral genetic material — but they all provide an answer in under 30 minutes.

Hosts are hiring doctors to screen guests before they attend their gatherings, or children coming in from out of town for sleepovers. Other people are getting tests to provide peace of mind after a particularly wild night. Event companies are offering rapid testing as a service to clients alongside catering and music. Instagram influencers are even touting the service.

Still, these rapid tests aren’t totally reliable, said Dr Demetre Daskalakis, New York City’s deputy commissioner of disease control. “Negatives are not definitive,” he said. (And there certainly have been false positives.)

“No test is 100 percent,” Dr Rashid said. “A negative test does not preclude one to not be carrying the virus.” Indeed, one reason rapid tests aren’t in widespread use is that they require additional testing to confirm. “We have to retest all of our negatives, so you’re doing two tests for everyone who is negative,” said Dr Daskalakis. “It’s a resource issue.”

He also warned that the virus can take some time to show up in a test result; though some test positive 48 hours after exposure, the two-week possible incubation period that has dictated quarantine is generally accepted. So if you were exposed to the virus even 10 days before your test, the outcome is still uncertain.