NEW YORK (NYTIMES) - On the morning that Broadway shut down in March 2020, Mr Joel Fram woke up feeling like a steamroller had rolled over him. He had a high fever, which evolved into a terrible sore throat and trouble breathing.

Like countless other New Yorkers, Mr Fram, the conductor of the Broadway show Company, had caught Covid-19 in the city's crushing first wave.

Two years later, he is still recovering.

His initial symptoms faded after a few weeks, but returned in the familiar constellation we now know as long Covid-19.

Fatigue so deep that he would fall asleep during a conversation. Shortness of breath. A constant, painful migraine behind his eye.

As cases of Covid-19 plunge around the United States, people are eager for any news that the pandemic may soon be over. But for those with long Covid-19 - it afflicts as many as 30 per cent of those who caught the coronavirus - the fight often goes on.

Mr Fram, 54, was used to having boundless energy. He could go to lunch, conduct a high-energy show like Wicked, do a Zoom call with his mother, bake a cake, wake up the next morning and do it again, a friend said.

Suddenly, he could not do a fraction of the things he would normally do.

"There was a period of time when all I could think about was long Covid," he said during one of many interviews over the past few months about how he finally became well enough to return for his Broadway show's reopening last November.

His story illustrates how determined - and fortunate - sufferers have to be to find the right care.

Mr Fram was not hospitalised, and by early April, he thought he had recovered.

But a few weeks later, things changed. During a yoga workout, he thought he would faint.

He developed joint pain, fatigue and breathlessness, feeling winded after walking just three blocks.

Unsure of how to get well, his anxiety ballooned.

In the summer of 2020, he took the next available appointment at Mount Sinai's Center for Post-Covid Care, one of the first long-Covid-19 clinics in the US.

It was six months away, in January 2021.

When January arrived, an intake physician sent him to a round of specialists: a rheumatologist for his swollen joints, a pulmonologist for his shortness of breath, a cardiologist for his chest tightness. Everything tested within normal range.

"On the one hand, that's great news," said Mr Fram. "On the other, it is a kind of doorway to existential despair, because it's like, what is wrong with me then?"

An enormous research effort is under way to determine exactly what long Covid-19 is and how to treat it.

The main hypotheses are that it is related to persistence of the virus in parts of the body, and to continuing inflammation related to the body's immune response to the virus.

Until there are clearer answers, treatment at post-Covid-19 clinics for broad symptoms such as fatigue and brain fog varies widely.

Some patients are offered physical therapy. Others get reassurance and practical tips such as stay well hydrated, or do daily, low-level exercise.

Dr Rany Condos, a pulmonologist who is the director of the Post-Covid Care programme at New York University, said about one-third of the patients at her clinic test normally on conventional measures despite debilitating fatigue or breathlessness.

She said one of her most important roles is to make these patients feel heard.

"Over the course of months, most patients slowly do improve," she said.

"Whether we have anything to do with this is not clear. In many of these cases, we are not really intervening."

At the Mount Sinai clinic, doctors told Mr Fram that his long-Covid-19 symptoms, like many people's, appeared to be a form of dysautonomia, a blanket term for a syndrome in which a person's autonomic nervous system - which controls heart rate, breathing and other processes - does not function normally.

As treatment, a cardiologist prescribed an intensive aerobic programme known as the Levine Protocol that is often used to treat another kind of dysautonomia, POTS (postural orthostatic tachycardia syndrome), a disorder in which sufferers can get light-headed just standing up.

Mr Fram started walking 30 minutes a day, then 40, up to 70. He hired a personal trainer and started doing sit-ups and planks.

But although he was getting through the exercise, he found that overall, his fatigue, headache and depression were getting worse.

His fatigue, which he put at about seven on a scale of one to 10 before, skyrocketed to a 13.

In late March last year, he e-mailed Dr David Putrino of Mount Sinai after someone mentioned him during a dinner.

To his surprise, Dr Putrino wrote back.

"It does sound like you're doing all the 'right' things here to no good effect, so let's see if we can really dig in and identify how to get you on track for recovery," he wrote.

Mr Fram soon learnt that Dr Putrino and his team - who were working for a separate centre treating long Covid-19 at Mount Sinai - do not recommend long-Covid-19 patients jumping into aerobic rehabilitation, as it tends to aggravate symptoms.

"We are not pushing people like we would with pulmonary rehab or cardiac rehab," Dr Putrino, director of Mount Sinai's Abilities Research Center, said in an interview.

Instead, his goal is to retrain the autonomous nervous system very gradually to respond as it did before Covid-19 threw it off balance.

In early April last year, Mr Fram had his first meeting with Ms Jenna Tosto, a physical therapist.

His first workouts were on his back, just doing leg lifts while wearing a heart monitor.

He began to see that his heart was not responding normally to exertion. Just lying on the exam table, his heart rate was 115, while a normal pulse might be 60 to 100.

Even low-level exercise was causing his heart rate to spike.

Mr Fram used Stasis breathing to retrain his nervous system to calm down during rest breaks. The basic technique was simple: Breathe in to the count of four, out to the count of six.

As the weeks went by, he started walking for three minutes, resting and breathing for two minutes, then walking three minutes more.

By September, he was finally allowed to go to the gym, but only to use the recumbent stationary bike, with two-minute breaks between brief periods of exertion.

On the four days a week he was not in the gym, Ms Tosto began to weave conducting practice into his regimen: Conduct for 15 minutes, then breathe for 10. Conduct for 20 minutes, then breathe for five.

Mr Fram made it back to rehearsals in October. The day of the first preview before a live audience, Nov 15, dawned bright and cold.

As the audience gathered outside the Jacobs Theater that night, Mr Fram took 20 minutes to lie on the floor in his dressing room, doing his Stasis breathing.

He stood at the helm of the 14-piece orchestra, perched on a platform above the stage. As the music began, he kept time with his whole body.

He still has good and bad stretches, which is common as progress in long Covid-19 is seldom linear.

Moving his body does not feel the same as it did, and he is not sure it ever will again.

But he is back to conducting his show on a full schedule.

"Because of my determination and because of the hope and the structure that all of these people have given me, I may be driving someone else's car, but I still can get us around the course in a way that I am proud of," he said this month.