When a pathogen jumps from animals and starts infecting people for the first time, it’s especially worrisome because most humans won’t have immunity to it yet. It’s usually the case, too, that doctors lack specific vaccines to prevent such an agent and medicines to treat it. So it is with the Covid-19 coronavirus that emerged late last year from China and is spreading rapidly around the world. No preventives or drugs have yet been approved against the virus, though scientists and companies are rushing to fill the void.

1. Why have I already read about treatments for it?

Notably, U.S. President Donald Trump has said he believes in the power of two malaria drugs, chloroquine and hydroxychloroquine, to fight the virus. His comments were based on small, short-term studies of the kind that many doctors conduct when faced with a new, lethal disease with no proven treatment. These studies, however, weren’t designed to prove the effectiveness of the drugs against the novel coronavirus. Even if a treatment shows promise in laboratory, animal or even early human experiments, rigorous testing is needed to prove that it’s both safe and effective. After Trump touted chloroquine as a “game changer,” an American man died and his wife was hospitalized after they self-medicated with the drug. Nigeria reported two cases of poisoning with it.

2. How do scientists prove a treatment is effective?

That requires carefully structured and monitored tests known as clinical trials. Typically, these studies are designed to show that patients who get the drug do better than those who don’t, and that the results aren’t a product of chance. The trials try to subtract all the other influences and factors that might disguise the true effectiveness of the drug. For one thing, patients often recover from viral illness on their own, or improve because of supportive care such as rest and hydration. And some really sick patients might not respond to treatment no matter how effective it is. Treatments that don’t have approval from regulators such as the U.S. Food and Drug Administration should be viewed with extreme caution. The FDA and the U.S. Federal Trade Commission have warned multiple companies to stop selling unproven treatments for coronavirus.

3. How long does it take to prove efficacy?

It depends. Drugs that are already approved against one infection and shown to be safe can be tested for effectiveness against another in a matter of months. Experimental drugs may take longer to test, as they have to go through initial studies to evaluate whether they are safe. Other factors that can slow the process include the supply of drug candidates and the availability of patients to test them in. The trials also have to be approved by ethics watchdogs and drug regulators. According to a 2017 review, the median time for regulators to approve a new drug in 2015 was 333 days in the U.S., 422 days in Europe, and 639 days in China. China has since expedited its process. When drugs are deemed to fill an immediate need, regulators can speed them through the approval process using a number of paths.

4. What’s being tested against Covid-19?

More than 100 clinical trials have been launched in China to study everything from anti-flu drugs and antibody-containing plasma from recovered patients, to traditional Chinese herbal medicine. A smaller number have been announced in countries including the U.S., South Korea and Thailand. World Health Organization researchers have identified as the most promising agent remdesivir, an experimental antiviral made by Gilead Sciences Inc. originally as a treatment for Ebola. In animal studies, it produced encouraging results against related coronaviruses that cause severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). Remdesivir trial results are expected from China in late April. Larger trials of chloroquine are starting. In a study in China published March 18, AbbVie Inc.’s Kaletra, an HIV treatment combining two drugs, failed to improve the condition of coronavirus patients. Another small, preliminary trial of the flu medication favipiravir, or Avigan, made by Fujifilm Holdings Corp. produced more promising results.

5. What about vaccines?

Moving at record speed, researchers began preliminary human testing of an experimental Covid-19 vaccine in mid-March in the Seattle area. It was developed by the U.S. National Institute of Allergy and Infectious Diseases in collaboration with the biotechnology company Moderna Inc. Some of the world’s biggest companies also are working on vaccine projects. GlaxoSmithKline has teamed up with the Chinese-based Clover Biopharmaceuticals, while Sanofi and Johnson & Johnson are in separate collaborations with the U.S. government’s Biomedical Advanced Research and Development Authority. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, said that it would take about a year and a half to complete trials, scale up production and make a vaccine widely available. There’s no guarantee trials will yield a successful vaccine, however. Moderna’s experimental product is a so-called messenger RNA vaccine, an unconventional approach that has yet to produce a vaccine licensed for human use. SARS killed nearly 800 people in a 2002-2003 outbreak, and there still isn’t an approved vaccine.

For more articles like this, please visit us at bloomberg.com

©2020 Bloomberg L.P.