Covid-19

NZ scientists on Covid-19 treatments

New Zealand scientists have responded cautiously to news of possible Covid-19 cures, even as Auckland City Hospital gears up to trial treatments locally, Marc Daalder reports

Auckland City Hospital will trial two potential treatments for Covid-19 - an anti-malaria drug and an anti-HIV drug. Patients with the disease who require general hospitalisation or intensive care will be offered the opportunity to participate in the studies, the University of Auckland's Mark Thomas said.

"Auckland City Hospital is one of a number of hospitals in New Zealand and Australia hoping to recruit patients into two clinical studies which will help to determine whether either an anti-malaria medicine, or an anti-HIV medicine, will help patients with Covid-19 disease to recover," Thomas, an Associate Professor of Clinical Molecular Medicine and Pathology, said.

"If patients or their family provide consent, they will be randomly allocated to treatment with hydroxychloroquine (an anti-malaria medicine), or with Kaletra (an anti-HIV medicine), or with a combination of both hydroxychloroquine and Kaletra, or with a placebo."

"This clinical trial will help us understand whether these drugs are effective therapies for Covid-19."

Efficacy unknown

Scientists have responded cautiously to the news that these drugs will be trialed in New Zealand and overseas, saying there is too little data at the moment to draw any conclusions about efficacy.

"There are a fair number of cures being mentioned in social media and by various public figures for Covid-19. This is normal human behaviour, people will try to do whatever they can to stay well and be able to care for their families and friends. However, there is very little data behind this," the University of Otago's Dr. Christopher Gale said in a written response. Gale is a senior lecturer in the Department of Psychological Medicine.

"There have been case reports from China and Italy of people in intensive care who have had various antiviral and antibiotic medications, but no clear indication that any of these helped. At present, however, we have no data. There is no point in seeking this medication or that - the medications we have available in New Zealand are for other conditions and are needed for those people!"

Kurt Krause, a Professor at the University of Otago's Department of Biochemistry, said a drug like this could be used as a stopgap measure while a purpose-built vaccine or treatment is developed.

"Direct acting antiviral drugs are being sought that target coronavirus in the hope that these drugs might serve as a bridge until a vaccine is developed. Since both drug and vaccine development take such a long time, interest has arisen in already approved drugs that can be repurposed to target Covid-19."

Three categories of drugs

Krause outlined the three categories of drugs that scientists were looking at: polymerase inhibitors, protease inhibitors and chloroquine.

Polymerase inhibitors have the greatest promise, Krause said, although they are not being trialled here.

"They work by blocking the enzyme that allows the virus to replicate its nucleic acid coding strand. If a virus cannot replicate its nucleic acid, it cannot replicate," he said.

Remdesivir, galidesivir - which was partly designed in New Zealand - and favipiravir are all examples of polymerase inhibitors. Remdesivir in particular has attracted international attention as a potential treatment. Results of a clinical trial in China are due next month, Krause said.

Protease inhibitors are developed to fight HIV by blocking an enxyme that processes proteins which the virus needs to grow, Krause said. Kaletra, one of the drugs being tested in New Zealand, is a protease inhibitor which seemed to have an impact during the SARS epidemic.

"Early data on its use for coronavirus infection suggests weak to no activity, but it was an early study with small patient numbers," Krause said.

The final category, which Krause simply labels "other", contains the drug chloroquine, which is commonly found in anti-malarial medicines. Chloroquine is the other medication being tested in New Zealand.

"Turns out that [chloroquine] happens to inhibit SARS2-CoV [the virus that causes Covid-19] replication in the test tube and it has garnered wide attention because of it. Physicians are keen to learn if this observation could be translated into success in living humans. A cautionary note is that chloroquine has been looked at before with other viruses and was not found to be effective."

Trials necessary

Krause said that a well-designed trial was crucial to proving the efficacy of any potential treatment.

"Although many of these compounds can, and are, being given now in an off-label fashion, the best way to use them is in a randomised controlled trial (RCT)," he said.

"That's because RCTs allow us to learn quickly if a drug actually works or not. RCTs have been essential in other viral epidemics and pandemics, like HIV for example, in learning the best most effective way of treating infections. RCT evaluation of these candidates would be the best way to sort their utility in treating Covid-19 infection."

Likewise, Gale said a trial will prove whether it's worth forging ahead with any given drug.

"What is happening is that various antiviral medications are being tested rapidly in the severe cases," he said. "It will not take much time (or participants in the trials) to see if such a medication works or does not. Some things will be shown to work, some will not."

Gale also hinted at the possibility that pharmaceutical companies - like Gilead, which owns remdesivir - might not be able to supply effective drugs or might be unwilling to do so at an affordable price.

"If and when we have treatments that work, then we will have to consider how we source them - which may include deliberately going off patent and getting pharmaceutical companies in New Zealand to make them."

The comment in this article was provided by the Science Media Centre.

Read more of Newsroom's Covid-19 coverage here. 

Covid-19 is transmitted like the flu. The Ministry of Health recommends that all New Zealanders wash their hands frequently and refrain from touching their face in order to protect themselves and others. Call Healthline on 0800 358 5453 if you have any symptoms and have been to any countries or territories of concern or have been in close contact with someone confirmed with Covid-19.

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