The Government has purchased 120,000 courses of two antiviral medications for treating Covid-19. But what is antiviral medication, how does it work, and do you still need to get the vaccine?

In our fight against Covid-19, we have used a range of tools to slow the spread of the virus and reduce its harm.

Some of these prevent infections and the spread of the virus like social distancing, mask use and vaccines. Others treat people who are already infected with coronavirus. 

In public health, preventative medicine like vaccines are the fence at the top of the cliff and treatment is an ambulance at the bottom of the cliff. 

It is better to put up a fence preventing someone from falling off the cliff than having an ambulance at the bottom to treat their injuries.

Aotearoa has made agreements to purchase 60,000 courses of a Covid-19 antiviral medicine called Molnupiravir and 60,000 courses of an antiviral drug from Pfizer called Paxlovid.

While this would help us reduce the harm and spread of Covid-19 in New Zealand, Pharmac chief executive Sarah Still said the Covid-19 vaccine was the best defence against the virus. 

Antiviral medication and other treatments are the second line of defence, Still said.

Antiviral medication is taken by people already infected by a virus to stop its spread and reduce the harm it causes, similar to how antibiotics are used to treat bacterial infections.

Like many antibiotics, antiviral medications do not destroy viruses. Instead, they stop them from replicating in our bodies. 

Viruses make copies of themselves by invading healthy cells and hijacking them to create more copies of themselves, destroying or harming our healthy cells in the process and flooding our bodies with viruses.

The Pfizer drug is an example of an inhibitor antiviral, targeting and disabling a specific enzyme in the virus. This enzyme is essentially the pair of scissors with which a virus cuts copies out of its own DNA. With it disabled, it is unable to replicate.

Early clinical testing by Pfizer of its antiviral drug, Paxlovid, showed an 89 percent reduction in the rate of hospitalisation and/or death of those infected with Covid-19 if taken within the first three days of showing mild to moderate symptoms.

In a Scientific American article, John Hopkins University scholar Dr Anmesh Adalja, who specialises in infectious diseases, wrote about why it was important to prioritise prevention over treatments for Covid-19.

The overuse of antiviral medication meant there was a risk that viruses could evolve to potentially become more harmful and resistant to treatment, Adalja said.  

The fewer people who catch Covid-19, the fewer people we have to treat with antivirals and the lower the chance of this happening, he said.

Adalja also highlighted the long term impacts Covid-19 has on the body. Research has shown 37 percent of people who catch Covid-19 experience health impacts three months after having recovered from the virus. Research has not shown if antiviral medication helps mitigate these long term impacts.

Pharmac, the government agency that decides which medicines are funded in New Zealand,  has trialled non-Covid specific treatments over the past year - including arthritis medication Tocilizumab and another antiviral inhibitor called remdesivir. 

Tocilizumab, for example, is an anti-inflammatory used to reduce the harmful inflammation caused by a Covid-19 infection. 

However, these new antivirals Molnupiravir and Paxvolid have been designed specifically for the treatment of Covid-19 and could be much more effective at treating it.

While Pharmac has signed these pre-purchase agreements for these antiviral medications, their release in New Zealand is dependent on approval by medical safety authority Medsafe. 

Medsafe will begin a review of these drugs early next year. 

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