Watch this explanation of Merck's 'molnupiravir' pill which will be used to treat severe COVID-19 cases in Australia

The molnupiravir pill - or 'molnu' as it's being shortened - has been developed by the American pharmaceutical company Merck, and is being touted as a simple, effective way to treat the respiratory disease from home.

During clinical trials of 775 patients were given the pills and measured against a control group who were given placebo drugs.

It proved to half the rate of hospitalisation and registered zero fatalities, whereas in the placebo group there were eight deaths.

The pill is the second anti-viral treatment, with the first to be approved as the monoclonal antibody sotrovimab.

This drug requires intravenous injection and can therefore only be administered in hospitals. So it's hoped that the molnu drug, once it's available, will be able to reduce the loading on the health system by keeping patients at home.

Associate Professor Nathan Bartlett is head of the viral immunology and respiratory disease group at the Hunter Medical Institute in Newcastle, NSW.

He explains that the tablet works similarly to drugs that already exist in the treatment of hepatitis and AIDS. It works by tricking the virus into duplicating itself as an inactive version inside the body.

"It's a class of drug we've been using for anti-virals for many years," he said.

"It's based on nucleotide analogue, so these are the building blocks of the genetic material of the virus, and these are synthetic versions of those building blocks that are essentially duds.

"It's what the virus needs to build its genetic material [so] if it incorporates this dud genetic material, it thinks it's a normal nucleotide, it incorporates it into the newly synthesised virus genome and it can't read that properly when it's making viral proteins.

"Essentially, it renders itself inactive."

The drug is yet to be approved by the Therapeutic Goods Administration (TGA). But already, the federal minister for health, Greg Hunt has announced the government has purchased 300,000 doses.

Professor Bartlett said the procurement indicates the drug will feature prominently in the nation's re-opening strategies.

"The fact that the government has purchased 300,000 doses at this point, demonstrates that this is going to be a key part of living with COVID once restrictions are eased."

It's expected that it will be used on only high-risk patients.

"For most of us, COVID normal will mean vaccination and if we do get the disease it will be a mild version that you can ride out at home," Professor Bartlett said.

"But there will be members of the community for whom the vaccines don't work as well, or the unvaccinated, who will need additional interventions to help them or to protect them.

"There are anti-virals available for influenza as well, and again they are not readily available they are prescribed by a physician based on the assessment of whether your flu will develop into a serious illness."

In most cases, the pill would be prescribed to be taken twice daily for five days while at home in isolation.

As to when it will be available, that will be dependent on the Therapeutic Goods Administration's assessment.

"That's up for the TGA to decide," Professor Bartlett said.

"We've seen with the vaccines, they can move on this very quickly."

With regards to the rumours circulating about the efficacy of ivermectin as a treatment for COVID-19, Professor Bartlett said there is no comparison with the new molnu pill.

"They're an entirely different class of drug.Ivermectin is an anti-parasitic drug, molnupiravir is an anti-viral drug, there's no similarities, no relatedness at all. It's mechanism of action is entirely different," he said.

"I personally don't understand it, there's no supportive clinical data at all to support ivermectin as an effective treatment for COVID-19. It's never been given approval because the data is just not there to support it."