The Covid-19 pandemic is one of the greatest challenges modern medicine has ever faced. Doctors and scientists are scrambling to find treatments and drugs that can save the lives of infected people and perhaps even prevent them from getting sick in the first place.

Below is an updated list of 20 of the most-talked-about treatments for the coronavirus. While some are accumulating evidence that theyre effective, most are still at early stages of research. We also included a warning about a few that are just bunk.

We are following 20 coronavirus treatments for effectiveness and safety:

Tentative or

mixed evidence

We are following 20 coronavirus treatments

for effectiveness and safety:

Tentative or

mixed evidence

We are following 20 coronavirus treatments

for effectiveness and safety:

There is no cure yet for Covid-19. And even the most promising treatments to date only help certain groups of patients and await validation from further trials. The F.D.A. has not fully licensed any treatment specifically for the coronavirus. Although it has granted emergency use authorization to some treatments, their effectiveness against Covid-19 has yet to be demonstrated in large-scale, randomized clinical trials.

This list provides a snapshot of the latest research on the coronavirus, but does not constitute medical endorsements. Always consult your doctor about treatments for Covid-19.

New additions and recent updates:

Added ivermectin, a drug typically used against parasitic worms that is being increasingly prescribed in Latin America. Aug. 10

Updated descriptions for several treatments. Aug. 10

We will update and expand the list as new evidence emerges. For details on evaluating treatments, see the N.I.H. Covid-19 Treatment Guidelines. For the current status of vaccine development, see our Coronavirus Vaccine Tracker.

WIDELY USED: These treatments have been used widely by doctors and nurses to treat patients hospitalized for diseases that affect the respiratory system, including Covid-19.

PROMISING EVIDENCE: Early evidence from studies on patients suggests effectiveness, but more research is needed. This category includes treatments that have shown improvements in morbidity, mortality and recovery in at least one randomized controlled trial, in which some people get a treatment and others get a placebo.

TENTATIVE OR MIXED EVIDENCE: Some treatments show promising results in cells or animals, which need to be confirmed in people. Others have yielded encouraging results in retrospective studies in humans, which look at existing datasets rather than starting a new trial. Some treatments have produced different results in different experiments, raising the need for larger, more rigorously designed studies to clear up the confusion.

NOT PROMISING: Early evidence suggests that these treatments do not work.

PSEUDOSCIENCE OR FRAUD: These are not treatments that researchers have ever considered using for Covid-19. Experts have warned against trying them, because they do not help against the disease and can instead be dangerous. Some people have even been arrested for their false promises of a Covid-19 cure.

EVIDENCE IN CELLS, ANIMALS or HUMANS: These labels indicate where the evidence for a treatment comes from. Researchers often start out with experiments on cells and then move onto animals. Many of those animal experiments often fail; if they dont, researchers may consider moving on to research on humans, such as retrospective studies or randomized clinical trials. In some cases, scientists are testing out treatments that were developed for other diseases, allowing them to move directly to human trials for Covid-19.

All treatmentsWidely usedPromisingTentative or mixedNot promisingPseudoscience

Antivirals can stop viruses such as H.I.V. and hepatitis C from hijacking our cells. Scientists are searching for antivirals that work against the new coronavirus.

PROMISING EVIDENCE EVIDENCE IN CELLS, ANIMALS AND HUMANSEMERGENCY USE AUTHORIZATIONRemdesivirRemdesivir, made by Gilead Sciences, was the first drug to get emergency authorization from the F.D.A. for use on Covid-19. It stops viruses from replicating by inserting itself into new viral genes. Remdesivir was originally tested as an antiviral against Ebola and Hepatitis C, only to deliver lackluster results. But preliminary data from trials that began this spring suggested the drug can reduce the recovery time of people hospitalized with Covid-19 from 15 to 11 days. (The study defined recovery as either discharge from the hospital or hospitalization for infection-control purposes only.) These early results did not show any effect on mortality, though retrospective data released in July hints that the drug might reduce death rates among those who are very ill.

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN CELLS, ANIMALS AND HUMANSFavipiravirOriginally designed to beat back influenza, favipiravir blocks a viruss ability to copy its genetic material. A small study in March indicated the drug might help purge the coronavirus from the airway, but results from larger, well-designed clinical trials are still pending.

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN CELLS, ANIMALS AND HUMANSMK-4482Another antiviral originally designed to fight the flu, MK-4482 (previously known as EIDD-2801) has had promising results against the new coronavirus in studies in cells and on animals. Merck, which has been running clinical trials on the drug this summer, has announced it will launch a large Phase III trial in September.Updated Aug. 6

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN CELLS Recombinant ACE-2To enter cells, the coronavirus must first unlock them a feat it accomplishes by latching onto a human protein called ACE-2. Scientists have created artificial ACE-2 proteins which might be able to act as decoys, luring the coronavirus away from vulnerable cells. Recombinant ACE-2 proteins have shown promising results in experiments on cells, but not yet in animals or people.

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN CELLS AND HUMANS IvermectinFor decades, ivermectin has served as a potent drug to treat parasitic worms. Doctors use it against river blindness and other diseases, while veterinarians give dogs a different formulation to cure heartworm. Studies on cells have suggested ivermectin might also kill viruses. But scientists have yet to find evidence in animal studies or human trials that it can treat viral diseases. As a result, Ivermectin is not approved to use as an antiviral.

In April, Australian researchers reported that the drug blocked coronaviruses in cell cultures, but they used a dosage that was so high it might have dangerous side effects in people. The FDA immediately issued a warning against taking pet medications to treat or prevent Covid-19. These animal drugs can cause serious harm in people, the agency warned.

Since then a number of clinical trials have been launched to see if a safe dose of ivermectin can fight Covid-19. In Singapore, for example, the National University Hospital is running a 5,000-person trial to see if it can prevent people from getting infected. As of now, theres no firm evidence that it works. Nevertheless ivermectin is being prescribed increasingly often in Latin America, much to the distress of disease experts.Updated Aug. 10

NOT PROMISING EVIDENCE IN CELLS AND HUMANS Lopinavir and ritonavirTwenty years ago, the F.D.A. approved this combination of drugs to treat H.I.V. Recently, researchers tried them out on the new coronavirus and found that they stopped the virus from replicating. But clinical trials in patients proved disappointing. In early July, the World Health Organization suspended trials on patients hospitalized for Covid-19. They didnt rule out studies to see if the drugs could help patients not sick enough to be hospitalized, or to prevent people exposed to the new coronavirus from falling ill. The drug could also still have a role to play in certain combination treatments.

NOT PROMISING EVIDENCE IN CELLS, ANIMALS AND HUMANSHydroxychloroquine and chloroquineGerman chemists synthesized chloroquine in the 1930s as a drug against malaria. A less toxic version, called hydroxychloroquine, was invented in 1946, and later was approved for other diseases such as lupus and rheumatoid arthritis. At the start of the Covid-19 pandemic, researchers discovered that both drugs could stop the coronavirus from replicating in cells.

Since then, theyve had a tumultuous ride. A few small studies on patients offered some hope that hydroxychloroquine could treat Covid-19. The World Health Organization launched a randomized clinical trial in March to see if it was indeed safe and effective for Covid-19, as did Novartis and a number of universities. Meanwhile, President Trump repeatedly promoted hydroxychloroquine at press conferences, touting it as a game changer, and even took it himself. The F.D.A. temporarily granted hydroxychloroquine emergency authorization for use in Covid-19 patients which a whistleblower later claimed was the result of political pressure. In the wake of the drugs newfound publicity, demand spiked, resulting in shortages for people who rely on hydroxychloroquine as a treatment for other diseases.

But more detailed studies proved disappointing. A study on monkeys found that hydroxychloroquine didnt prevent the animals from getting infected and didnt clear the virus once they got sick. Randomized clinical trials found that hydroxychloroquine didnt help people with Covid-19 get better or prevent healthy people from contracting the coronavirus. Another randomized clinical trial found that giving hydroxychloroquine to people right after being diagnosed with Covid-19 didnt reduce the severity of their disease. (One large-scale study that concluded the drug was harmful as well was later retracted.) The World Health Organization, the National Institutes of Health and Novartis have since halted trials investigating hydroxychloroquine as a treatment for Covid-19, and the F.D.A. revoked its emergency approval. The F.D.A. now warns that the drug can cause a host of serious side effects to the heart and other organs when used to treat Covid-19.

In July, researchers at Henry Ford hospital in Detroit published a study finding that hydroxychloroquine was associated with a reduction in mortality in Covid-19 patients. President Trump praised the study on Twitter, but experts raised doubts about it. The study was not a randomized controlled trial, in which some people got a placebo instead of hydroxychloroquine. The studys results might not be due to the drug killing the virus. Instead, doctors may have given the drug to people who were less sick, and thus more likely to recover anyway.

Despite negative results, a number of hydroxychloroquine trials have continued, although most are small, testing a few dozen or a few hundred patients. A recent analysis by STAT and Applied XL found more than 180 ongoing clinical trials testing hydroxychloroquine or chloroquine, for treating or preventing Covid-19. Although its clear the drugs are no panacea, its theoretically possible they could provide some benefit in combination with other treatments, or when given in early stages of the disease. Only well-designed trials can determine if thats the case.Updated Aug. 10

Most people who get Covid-19 successfully fight off the virus with a strong immune response. Drugs might help people who cant mount an adequate defense.

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN CELLS AND HUMANS Convalescent plasmaA century ago, doctors filtered plasma from the blood of recovered flu patients. So-called convalescent plasma, rich with antibodies, helped people sick with flu fight their illness. Now researchers are trying out this strategy on Covid-19. In May, the F.D.A. designated convalescent plasma an investigational product. That means that despite not yet being shown as safe and effective, plasma can be used in clinical trials and given to some patients who are seriously ill with Covid-19. Tens of thousands of patients in the U.S. have received plasma through a program launched by the Mayo Clinic and the federal government.

The Trump administration has praised convalescent plasma, despite the lack of evidence yet that it works. The first wave of trials have been small and the results have been mixed. Large randomized clinical trials are underway, but theyve struggled to enroll enough participants, some of whom worry they will receive a placebo instead of the treatment itself.

Experts say that its vital to complete these trials to determine if convalescent plasma is safe and effective. If these trials are successful, it could serve as an important stopgap measure until more potent therapies become widely available.Updated Aug. 10

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN CELLS, ANIMALS AND HUMANSMonoclonal antibodiesConvalescent plasma from people who recover from Covid-19 contains a mix of different antibodies. Some of the molecules can attack the coronavirus, but many are directed at other pathogens. Researchers have sifted through this slurry to find the most potent antibodies against Covid-19. They have then manufactured synthetic copies of these molecules, known as monoclonal antibodies. Researchers have begun investigating them as a treatment for Covid-19, either individually or in cocktails.

Monoclonal antibodies were first developed as a therapy in the 1970s, and since then the F.D.A. has approved them for 79 diseases, ranging from cancer to AIDS. Since the start of the pandemic, researchers have found dozens of monoclonal antibodies that show promise against Covid-19 in preclinical studies on cells and animals. Companies like Eli Lilly and Regeneron recently began clinical trials studying monoclonal antibodies. Several other firms, as well as teams at universities, are slated to enter the race soon as well.Updated Aug. 10

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN CELLS, ANIMALS AND HUMANSInterferonsInterferons are molecules our cells naturally produce in response to viruses. They have profound effects on the immune system, rousing it to attack the invaders, while also reining it in to avoid damaging the bodys own tissues. Injecting synthetic interferons is now a standard treatment for a number of immune disorders. Rebif, for example, is prescribed for multiple sclerosis.

As part of its strategy to attack our bodies, the coronavirus appears to tamp down interferon. That finding has encouraged researchers to see whether a boost of interferon might help people weather Covid-19, particularly early in infection. Early studies, including experiments in cells and mice, have yielded encouraging results that have led to clinical trials.

An open-label study in China suggested that the molecules could help prevent healthy people from getting infected. On July 20, the British pharmaceutical company Synairgen announced that an inhaled form of interferon called SNG001 lowered the risk of severe Covid-19 in infected patients in a small clinical trial. The full data have not yet been released to the public, or published in a scientific journal. On August 6, the National Institute of Allergy and Infectious Diseases launched a Phase III trial on a combination of Rebif and the antiviral remdesivir, with results expected by fall 2020.Updated Aug. 10

The most severe symptoms of Covid-19 are the result of the immune systems overreaction to the virus. Scientists are testing drugs that can rein in its attack.

PROMISING EVIDENCE EVIDENCE IN HUMANS DexamethasoneThis cheap and widely available steroid blunts many types of immune responses. Doctors have long used it to treat allergies, asthma and inflammation. In June, it became the first drug shown to reduce Covid-19 deaths. That study of more than 6,000 people, which in July was published in the New England Journal of Medicine, found that dexamethasone reduced deaths by one-third in patients on ventilators, and by one-fifth in patients on oxygen. It may be less likely to help and may even harm patients who are at an earlier stage of Covid-19 infections, however. In its Covid-19 treatment guidelines, the National Institutes of Health recommends only using dexamethasone in patients with COVID-19 who are on a ventilator or are receiving supplemental oxygen.

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN HUMANS Cytokine InhibitorsThe body produces signaling molecules called cytokines to fight off diseases. But manufactured in excess, cytokines can trigger the immune system to wildly overreact to infections, in a process sometimes called a cytokine storm. Researchers have created a number of drugs to halt cytokine storms, and they have proven effective against arthritis and other inflammatory disorders. Some turn off the supply of molecules that launch the production of the cytokines themselves. Others block the receptors on immune cells to which cytokines would normally bind. A few block the cellular messages they send. Depending on how the drugs are formulated, they can block one cytokine at a time, or muffle signals from several at once.

Against the coronavirus, several of these drugs have offered modest help in some trials, but faltered in others. Drug companies Regeneron and Roche drug both recently announced that two drugs called sarilumab and tocilizumab, which both target the cytokine IL-6, did not appear to benefit patients in Phase 3 clinical trials. Many other trials remain underway, several of which combine cytokine inhibitors with other treatments.Updated Aug. 10

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN HUMANS EMERGENCY USE AUTHORIZATIONBlood filtration systemsThe F.D.A. has granted emergency use authorization to several devices that filter cytokines from the blood in an attempt to cool cytokine storms. One machine, called Cytosorb, can reportedly purify a patients entire blood supply about 70 times in a 24-hour period. A small study in March suggested that Cytosorb had helped dozens of severely ill Covid-19 patients in Europe and China, but it was not a randomized clinical trial that could conclusively demonstrate it was effective. A number of studies on blood filtration systems are underway, but experts caution that these devices carry some risks. For example, such filters could remove beneficial components of blood as well, such as vitamins or medications.Updated Aug. 10

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN HUMANS Stem cellsCertain kinds of stem cells can secrete anti-inflammatory molecules. Over the years, researchers have tried to use them as a treatment for cytokine storms, and now dozens of clinical trials are under way to see if they can help patients with Covid-19. But these stem cell treatments havent worked well in the past, and its not clear yet if theyll work against the coronavirus.

Doctors and nurses often administer other supportive treatments to help patients with Covid-19.

WIDELY USEDProne positioningThe simple act of flipping Covid-19 patients onto their bellies opens up the lungs. The maneuver has become commonplace in hospitals around the world since the start of the pandemic. It might help some individuals avoid the need for ventilators entirely. The treatments benefits continue to be tested in a range of clinical trials.

WIDELY USEDEMERGENCY USE AUTHORIZATIONVentilators and other respiratory support devicesDevices that help people breathe are an essential tool in the fight against deadly respiratory illnesses. Some patients do well if they get an extra supply of oxygen through the nose or via a mask connected to an oxygen machine. Patients in severe respiratory distress may need to have a ventilator breathe for them until their lungs heal. Doctors are divided about how long to treat patients with noninvasive oxygen before deciding whether or not they need a ventilator. Not all Covid-19 patients who go on ventilators survive, but the devices are thought to be lifesaving in many cases.

TENTATIVE OR MIXED EVIDENCE EVIDENCE IN HUMANS AnticoagulantsThe coronavirus can invade cells in the lining of blood vessels, leading to tiny clots that can cause strokes and other serious harm. Anticoagulants are commonly used for other conditions, such as heart disease, to slow the formation of clots, and doctors sometimes use them on patients with Covid-19 who have clots. Many clinical trials teasing out this relationship are now underway. Some of these trials are looking at whether giving anticoagulants before any sign of clotting is beneficial.

False claims about Covid-19 cures abound. The F.D.A. maintains a list of more than 80 fraudulent Covid-19 products, and the W.H.O. debunks many myths about the disease.

WARNING: DO NOT DO THISDrinking or injecting bleach and disinfectantsIn April, President Trump suggested that disinfectants such as alcohol or bleach might be effective against the coronavirus if directly injected into the body. His comments were immediately refuted by health professionals and researchers around the world as well as the makers of Lysol and Clorox. Ingesting disinfectant would not only be ineffective against the virus, but also hazardous possibly even deadly. In July, Federal prosecutors charged four Florida men with marketing bleach as a cure for COVID-19.

WARNING: NO EVIDENCEUV lightPresident Trump also speculated about hitting the body with ultraviolet or just very powerful light. Researchers have used UV light to sterilize surfaces, including killing viruses, in carefully managed laboratories. But UV light would not be able to purge the virus from within a sick persons body. This kind of radiation can also damage the skin. Most skin cancers are a result of exposure to the UV rays naturally present in sunlight.

WARNING: NO EVIDENCESilverThe F.D.A. has threatened legal action against a host of people claiming silver-based products are safe and effective against Covid-19 including televangelist Jim Bakker and InfoWars host Alex Jones. Several metals do have natural antimicrobial properties. But products made from them have not been shown to prevent or treat the coronavirus.

Note: After additional discussions with experts we have adjusted several labels on the tracker. The Strong evidence label has been removed until further research identifies treatments that consistently benefit groups of patients infected by the coronavirus. In its place, Promising evidence will be used for drugs such as remdesivir and dexamethasone that have shown promise in at least one randomized controlled trial, and Widely used for treatments such as proning and ventilators that are often used with severely ill patients, including those with Covid-19. And we may reintroduce the Ineffective label when ongoing clinical trials repeatedly end with disappointing results.

Sources: National Library of Medicine; National Institutes of Health; William Amarquaye, University of South Florida; Paul Bieniasz, Rockefeller University; Jeremy Faust, Brigham & Womens Hospital; Matt Frieman, University of Maryland School of Medicine; Noah Haber, Stanford University; Swapnil Hiremath, University of Ottawa; Akiko Iwaskai, Yale University; Paul Knoepfler, University of California, Davis; Elena Massarotti, Brigham and Womens Hospital; John Moore and Douglas Nixon, Weill Cornell Medical College; Erica Ollman Saphire, La Jolla Institute for Immunology; Regina Rabinovich, Harvard T.H. Chan School of Public Health; Ilan Schwartz, University of Alberta; Phyllis Tien, University of California, San Francisco.

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Coronavirus Drug and Treatment Tracker - The New York Times