Guidance on how to treat the disease was scant, and medical studies were being performed so hastily they couldn’t always be trusted.

“You felt very helpless,” said Patel, an infectious disease doctor at the hospital. “I’m standing in front of a patient, watching them struggle to breathe. What can I give them?” While there is still no simple answer to that question, a lot has changed in the six months since an entirely new coronavirus began sweeping the globe.

Doctors say they’ve learned enough about the highly contagious virus to solve some key problems for many patients. The changes could be translating into more saved lives, although there is little conclusive data.

Nearly 30 doctors around the world, from New Orleans to London to Dubai, told Reuters they feel more prepared should cases surge again.

“We are well-positioned for a second wave,” Patel said. “We know so much more.” Doctors like Patel now have:

*A clearer grasp of the disease’s side effects, like blood clotting and kidney failure *A better understanding of how to help patients struggling to breathe *More information on which drugs work for which kinds of patients.

They also have acquired new tools to aid in the battle, including:

*Widespread testing *Promising new treatments like convalescent plasma, antiviral drugs and steroids *An evolving spate of medical research and anecdotal evidence, which doctors share across institutions, and sometimes across oceans.

Despite a steady rise in Covid-19 cases, driven to some extent by wider testing, the daily death toll from the disease is falling in some countries.

Doctors say they are more confident in caring for patients than they were in the chaotic first weeks of the pandemic, when they operated on nothing but blind instinct.

There is still no surefire treatment for Covid-19, the disease caused by the new virus, which often starts as a respiratory illness but can spread to attack organs including the heart, liver, kidneys or central nervous system. Scientists are at least months away from a working vaccine.

And while medical knowledge has improved, doctors continue to emphasize that the best way for people to survive is to avoid infection in the first place through good hygiene, face coverings and limited group interaction.

Around 15% of Covid-19 patients are at risk of becoming sick enough to require hospitalisation. Scientists have estimated that the fatality rate could be as high as 5%, but most put the number well below 1%. People with the highest risk of severe disease include older adults and those with underlying health conditions like heart disease, diabetes and obesity.

Hospitals said some of their early hunches about best treatments for Covid-19 patients ended up being wrong. Case in point: use of the anti-malaria pill hydroxychloroquine.

It gained attention in March, when US President Donald Trump began publicly touting it. Early reports showed the drug could have some benefit, and hospitals, desperate for solutions, started giving it to critically sick patients. But subsequent trial data have told a different story, suggesting the drug is not effective for treatment or prevention, and might even cause harm. Other clinical trials of the drug are still underway.

But even if hydroxychloroquine looks unlikely as an effective Covid-19 treatment, hospitals continue to try new medications - both by repurposing older drugs and exploring novel therapies. Patients are being enrolled in hundreds of coronavirus clinical trials launched in the past three months.

Many hospitals said they are seeing success with the use of plasma donated by survivors of Covid-19 to treat newly infected patients.

People who survive an infectious disease like Covid-19 are generally left with blood containing antibodies, which are proteins made by the body’s immune system to fight off a virus. The blood component that carries the antibodies, known as convalescent plasma, can be collected and given to new patients.

Early results from a study at New York’s Mount Sinai Hospital found that patients with severe Covid-19 who were given convalescent plasma were more likely to stabilize or need less oxygen support than other similar hospital patients. But results from other studies have been mixed, and doctors still await findings from a rigorously-designed trial. And availability of plasma varies between regions.

At Henry Ford Hospital in Detroit, Michigan, “anecdotally everyone can provide stories” of the benefits of plasma, said Dr. John Deledda, the hospital’s chief medical officer.

But in rural New Mexico, hospitals that care for largely underserved populations struggle to find it. “There’s a limited number of blood centers” that can provide plasma, said Valory Wangler, chief medical officer at Rehoboth McKinley Christian Health Care Services, in Gallup, New Mexico. Until trial data is more conclusive, plasma is “not something we’re pursuing actively,” she said.

Dr Abdullatif al-Khal, head of infectious diseases at Qatar’s Hamad Medical Corporation and a co-chair of the country’s pandemic preparedness team, said he saw patients improve after he started using donated plasma early in the course of Covid-19 before the patients deteriorated.

Qatar is also assessing a steroid known as dexamethasone to treat Covid-19. But Khal says he wants to wait for publication of clinical data behind a recent UK study suggesting that the steroid reduced death rates by around a third among the most severely ill Covid-19 patients.

In patients with severe Covid-19, the immune system can overreact, triggering a potentially harmful cascade. Steroids are an older class of drugs that suppress that inflammatory response. But they can also make it easier for other viral or bacterial infections to take hold - making doctors leery of their use in a hospital setting or in patients with early-stage Covid-19.

Some countries, including Bahrain and the United Arab Emirates, reported using HIV drugs lopinavir and ritonavir with some success. Clinical trials, though, have suggested little benefit.

Many of the doctors who spoke with Reuters were bullish on the use of remdesivir, the only drug so far shown to be effective against the coronavirus in a rigorous clinical trial. The antiviral developed by California-based Gilead Sciences Inc (GILD.O) was shown to reduce the length of hospital stays for COVID-19 patients by about a third, but hasn’t been proven to boost survival.

Remdesivir is designed to disable the mechanism by which certain viruses, including the new coronavirus, make copies of themselves and potentially overwhelm their host’s immune system.

It is available under emergency approvals in several countries, including the United States. But Gilead’s donated supplies are limited, and distribution and availability are uneven.

Dr. Andrew Staricco, chief medical officer at McLaren Health Care, which operates 11 hospitals across Michigan, recalls the urgency to obtain remdesivir early on.

The drug was so precious, he said, that state police troopers were responsible for transporting it to the hospital - which they did, dropping it off around 1am the next morning.

Health officials originally directed remdesivir for use on the most critically ill patients. But doctors later found they got the best results administering it earlier.

“We started finding that, actually, the sooner you get treated with it, the better,” Staricco said. “We’ve revisited our criteria for giving it to patients three different times.” Data on the drug, he said, is still scarce. But his anecdotal observations on the benefits of early treatment were echoed by several US doctors.

So much so that Donald Trump caused controversy this week when it emerged the total global supply of the drug for the next three months.

The US health department announced on Tuesday it had agreed to buy 500,000 doses for use in American hospitals.

Tests suggest remdesivir cuts recovery times, though it is not yet clear if it improves survival rates.

Although much about the coronavirus remains unknown, a key reason hospitals say they now are more prepared owes to teamwork.

Many doctors described a kind of unofficial network of information sharing.

In hard-hit Italy, Dr. Lorenzo Dagna of the IRCCS San Raffaele Scientific Institute in Milan, organised conference calls with institutions in the United States and elsewhere to share experiences and anecdotes treating COVID-19 patients.

McLaren’s Staricco said the Michigan hospital chain adopted its policy on use of blood thinners by looking at peers at Detroit Medical Center and Vanderbilt University Medical Center.

As more institutions put their guidelines online, he said, there was “lots of copy-catting going on.”