Australian scientists insist hydroxychloroquine COULD prevent people catching COVID-19 after giving the controversial drug to hundreds of health care workers

Australian scientists have vowed to continue investigating whether taking hydroxychloroquine can stop people becoming infected with coronavirus.

Researchers from the Walter & Eliza Hall Institute in Melbourne believe the drug could prevent people catching SARS-CoV-2 - the virus that causes COVID-19.

Hundreds of health workers in NSW and Victoria have been given the drug in the Institute's COVID SHIELD trial in an effort to try and determine its effectiveness as a prophylactic. 

Hydroxychloroquine was brought to public attention when US President Donald Trump said he was using the malaria drug to 'protect' himself from coronavirus.

Melbourne researchers believe hydroxychloroquine could prevent COVID-19

Prescriptions for the drug subsequently skyrocketed, before it was removed from major testing trials as it proved to be ineffective in reducing the impact of COVID-19. 

Scientific journal The Lancet published and later retracted a study based on false data that claimed coronavirus cases taking hydroxychloroquine had an increased death rate.

COVID SHIELD co-lead investigator Marc Pelligrini said researchers were not considering the drug as a treatment, but as a preventative. 

'The evidence that shows that the drug doesn’t particularly help with treatment really never deterred us because we always thought that ... if the drug did have a role in preventing people from getting COVID-19, it has to be even before they were exposed to SARS-CoV-2,' he told The Australian.

Scientists from the Walter & Eliza Hall Institute in Melbourne are studying whether the drug works as a prophylactic for COVID-19

Test tube studies have found hydroxychloroquine can work to impede the replication of COVID-19 and discourage proliferation. 

Claire Lobb is an emergency care nurse at The Alfred Hospital and among about 230 frontline healthcare workers signed up for the four-month trial.

'Hydroxychloroquine is a drug that is cheap and readily available, with very few side effects. If there is a chance this drug could help prevent frontline healthcare workers from getting COVID-19, I think it is important that we do a proper clinical trial to test it,' she said.

Ms Lobb said she was keen to be involved and excited at the prospect of finding out whether the drug was useful as a prophylactic. 

'To have a drug that is cheap and widely available to reduce transmission of the virus to frontline healthcare workers would be really helpful, especially while we are waiting for a vaccine,' she said.

Nurse Claire Lobb (pictured right) is among 230 front line health care workers who have signed up to the COVID SHIELD trial of hydroxychloroquine

While the Australian researchers remain hopeful hydroxychloroquine could prevent COVID-19, a U.S. study found on Thursday the drug offers no protection.

Researchers at the University of Pennsylvania found about 6.3 per cent of hospital workers who took the drug regularly caught the virus, compared to 6.6 per cent of people who didn't.

The effect, they said, was 'negligible' and although a slightly higher proportion of people without the drug became sick, it was not a big enough difference to suggest hydroxychloroquine worked.

Whether or not the medicine could help treat people who already had Covid-19 was not studied. 

WHY IS HYDROXY-CHLOROQUINE CONTROVERSIAL? 

Hydroxychloroquine - branded as Plaquenil - is a cheap drug that has been used to prevent malaria and treat lupus and rheumatoid arthritis for decades.

It was touted as a wonder drug by Donald Trump despite no evidence it could treat Covid-19. 

Hope was sparked early on in the crisis when a French study suggested the drug could have both antiviral and anti-inflammatory effects.

It triggered a flurry of research across the world, the endorsement from Trump and emergency authorization from US regulators.

The RECOVERY trial is the first randomised study to provide concrete evidence about the drug.

The results will likely have a knock-on effect around the globe, where tens of thousands of coronavirus patients are still being prescribed hydroxychloroquine. 

Leading doctors have also warned the drug can cause severe side effects, and can even throw off the process that makes the heart beat in time.

One trial in Brazil was stopped short because so many of the enrolled coronavirus patients given the drug developed these arrhythmias (abnormal heartbeats).

According to WebMD, side effects may include: