Coronavirus treatments: five alternatives to vaccines

While we wait for a coronavirus vaccine, the World Health Organization (WHO) has launched a global trial of drugs that could be used to treat those who already have COVID-19. Here are five possible coronavirus treatments that WHO has been investigating.

Remdesivir is the frontrunner in the trial. It was originally developed by US biotechnology company Gilead Sciences to treat Ebola. It inhibits an enzyme called ‘RNA-dependent RNA polymerase’ that viruses need to replicate.

A study in 2017 showed that it can inhibit the SARS and MERS coronaviruses. The first COVID-19 patient in the US was given remdesivir when his condition deteriorated, and a case report in the New England Journal Of Medicine said that his condition improved the next day.

Chloroquine and hydroxychloroquine are two drugs usually used to treat malaria and, among other conditions, rheumatoid arthritis. There have been reports from China that chloroquine was an effective treatment for COVID-19, and a trial of hydroxychloroquine in France showed it reduced numbers of the virus in nasal swabs.

But many virologists are being cautious, pointing out that hydroxychloroquine has been studied as an antiviral for years, but trials have not worked out.

In fact, WHO's test of hydroxychloroquine has been discontinued, since the trials showed 'little or no reduction in the mortality of hospitalised COVID-19 patients'.

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Ritonavir and lopinavir is a combination drug – both are given together – and it’s already used to treat HIV infections. It works by blocking a type of enzyme called a protease, which is used when new viruses are being built. It’s known to work with other viruses, too – including coronaviruses.

A trial in Wuhan, China, didn’t fare well, with the patients not doing any better than those not given the drugs. But the doctors involved said that the patients given the drug may have been too ill to benefit.

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One blend of medicine combines the antiviral HIV drugs, ritonavir and lopinavir, with interferon beta, a protein which regulates inflammation in the body and is used to treat multiple sclerosis.

This combination is already being tested in a trial in Saudi Arabia as a treatment for the coronavirus that causes MERS. A separate trial, involving University of Southampton researchers, is testing interferon beta on its own in COVID-19 hospital patients in the UK.

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While not part of the WHO trial, the idea behind convalescent serum is simple. People who have recovered from COVID-19 will have produced antibodies to fight off the virus. So why not take some of their blood, separate off the plasma that includes the antibodies, and inject it into COVID-19 patients?

Convalescent serum has already been used to treat SARS and MERS. The US Food and Drug Administration (FDA) has approved a trial against COVID-19 at dozens of hospitals across the US.