PERTH, Australia – In preparation for easing COVID-19 restrictions and opening its international borders, Australia has added a new vaccine and two new oral antiviral therapies to its arsenal to fight the omicron variant of the SARS-CoV-2 virus that is sweeping the globe.

Australia’s Therapeutic Goods Administration (TGA) granted provisional approval on Jan. 20 to Biocelect Pty Ltd. (on behalf of Novavax Inc.) for its COVID-19 vaccine, Nuvaxovid, as well as two oral antiviral treatments, MSD Australia’s Lagevrio (molnupiravir) and Pfizer Inc.’s combination treatment Paxlovid (nirmatrelvir/ritonavir).

Nuvaxovid is a protein-based vaccine engineered from the genetic sequence of the first strain of SARS-CoV-2. It was created using Novavax's recombinant nanoparticle technology to generate antigen derived from the coronavirus spike (S) protein and is formulated with Novavax's saponin-based Matrix-M adjuvant.

The first protein COVID-19 vaccine approved in the country, Nuvaxovid is indicated for active immunization to prevent COVID-19 in people 18 and older. The vaccine is to be given in two doses administered three weeks apart. It is cleared for primary vaccination only, as studies for use as a booster dose and in pediatric patients are ongoing.

Novavax and the Australian government announced an advance purchase agreement for 51 million doses of Novavax's COVID-19 vaccine in January 2021. The first shipment to Australia of the Novavax vaccine is expected in February 2022.

“This vaccine started its clinical trial journey in Australia, and I was fortunate to be the principal investigator on that study that administered this vaccine to healthy volunteers for the first time on the May 26, 2020,” said Paul Griffin, director of Infectious Diseases at Mater Health Services.

“Following the success of this study, this vaccine was then subsequently studied intensively in large clinical trials around the world that demonstrated an efficacy rate above 90% and a favorable safety profile,” said Griffin, who is also an associate professor of Medicine at the University of Queensland and medical director and principal investigator at Q-Pharm, Nucleus Network.

The vaccine can be stored for nine months at standard refrigeration temperatures, he said.

The approval for provisional registration is further supported by two pivotal Phase III clinical trials that enrolled nearly 30,000 participants in the U.S. and Mexico, and a trial with almost 15,000 participants in the U.K.

Nuvaxovid is the fifth COVID-19 vaccine to be provisionally cleared in Australia. Astrazeneca plc’s Vaxzevria was the first to be approved in the country, but uptake was slow due to the associated rare side effects of blood clots. The TGA has provisionally approved Pfizer Inc.-Biontech SE’s Comirnaty, Moderna Inc.’s Spikevax and Johnson & Johnson’s vaccine.

Provisional approval is subject to certain conditions, such as the requirement to provide information to the TGA on longer-term efficacy and safety from ongoing clinical trials and postmarket assessment.

First oral treatments cleared

The two oral, prescription-only antivirals – Lagevrio and Paxlovid – are taken twice a day for five days, and they work by reducing the virus's ability to rapidly multiply. The TGA said the treatments are not a substitute for the COVID-19 vaccine.

Lagevrio is most effective when taken during the early stages of infection and is recommended for use as soon as possible following a positive COVID-19 test and within five days of symptoms onset.

Paxlovid tablets are indicated for the treatment of mild to moderate COVID-19 in adults with positive test results, and who are at high risk for progression to severe COVID-19, including hospitalization or death.

"Today is a big step forward in our battle with this virus,” Griffin said. “While we have been extremely fortunate to have safe and effective vaccines, which will remain the backbone of our strategy moving forward, and we have already been using antibody and antiviral therapy we can give intravenously, the addition of safe and effective antivirals that can be given orally, in my opinion, will make an enormous difference.

“Given these antiviral medications are administered orally, they can be used more in the community setting and have been shown to work well particularly at reducing the risk of going to hospital and progressing to more severe disease in people who are high risk of doing so when infected with the SARS-CoV-2 virus.”

Lagevrio targets the machinery that replicates the viral genome, while Paxlovid targets the viral protease that is essential for infectivity and is formulated with ritonavir, which boosts the therapeutic levels of the active drug, said Jill Carr, laboratory head in microbiology and infectious diseases in the College of Medicine and Public Health at Flinders University

In October 2021, Pfizer announced an agreement with the Australian government to supply 500,000 treatment courses of Paxlovid over 2022. Pfizer will begin delivering the first treatment courses from the first quarter of 2022.

Also in October 2021, the Australian government entered an agreement with MSD to secure 300,000 treatment courses of Lagevrio once provisionally approved.