When COVID-19 first arrived on our shores, there were no drug treatments for severe cases and no vaccine.
Over time, drug treatments became available for those with severe COVID-19 infections. Remdesivir was first to be provisionally approved by the Therapeutic Goods Administration (TGA) in July 2020. A broad-spectrum antiviral developed to fight Hepatitis C, the drug shortens the hospitalisation time for those with severe COVID-19.
While some worked on treatment, others worked on prevention. In January 2021, the TGA provisionally approved the use of the Pfizer (Comirnaty) mRNA vaccine. A few weeks later, the TGA provisionally approved the AstraZeneca (Vaxzevria) viral vector vaccine.
Since then, a number of new vaccines and drug treatments have been given provisional approval by the TGA. In this article, we cover some of the most promising new innovations in the fight against COVID-19.
Moderna’s Spikevax is an mRNA vaccine, similar to Comirnaty. It was given provisional approval by the TGA in August 2021 for adults, and provisionally approved for people aged 12 to 17 years in September 2021. People need to have two doses of the
vaccine, at least four weeks apart. Spikevax and Comirnaty are approved for use as boosters regardless of which drug was given first.
Spikevax differs from Comirnaty in the coding of the mRNA sequence used by the body to build the COVID-19 spike protein, and in the formulation of the lipid (fat) coating around the mRNA sequences. Spikevax has a slight advantage in effectiveness of preventing infection, hospitalisation and death against the Alpha variant.1 There are no peer-reviewed studies into the effectiveness of Spikevax against the Omicron variant.
Like Comirnaty, Spikevax has side effects including pain at the injection site, tiredness, headache, muscle pain, fever, chills, and joint pain. Some less common side effects include redness or swelling at the injection site, swelling or tenderness in the armpit, nausea/vomiting and enlarged lymph nodes. In rare cases, myocarditis (inflammation of the heart) and pericarditis (inflammation of the membrane around the heart) can develop after vaccination with Spikevax (Australian Government Department of Health, 2021).
Novavax’s Nuvaxovid vaccine is a protein-based vaccine. It uses a modified version of the COVID-19 spike protein, attached to a lipid (fat-like) nanoparticle with up to 14 spikes embedded in each. The TGA provisionally approved Novavax for use on adults in January 2022 and it was made available to the public on 15 February. Patients need to have two doses, given at least three weeks apart. It is not currently approved for use as a booster.
As Nuvaxovid only carries the spike protein, it cannot give you COVID-19.
Nuvaxovid is effective (on the Alpha variant) and safe for use when given 21 days apart (Dunkle et al, 2021; Heath et al, 2021). Its main advantage over the mRNA vaccines is that it can be stored at standard refrigerator temperatures and is much cheaper to produce. This makes it much better for developing countries.
Nuvaxovid also has fewer side-effects than mRNA vaccines. Common side-effects include injection site pain or tenderness, tiredness, headache, muscle or joint pain, and generally feeling unwell. Rare side-effects of the vaccine include anaphylaxis.
Lagevrio is the trading name for the drug Molnupiravir, produced by Merck Sharp & Dohme in Australia. Lagevrio works by introducing copy errors into the RNA strands of viruses, making them unable to reproduce. Originally an influenza drug, it was shelved because of concerns about a potential to increase genetic mutation (mutagenicity). It was provisionally approved for use by adults in January 2022.
Lagevrio is recommended for people at high risk of hospitalisation from COVID-19 and have tested positive. To be effective, the regime must begin within five days of the start of symptoms. The patient takes 800mg every 12 hours for five days. This course of medication reduces the risk of hospitalisation and death in the unvaccinated by up to 50 per cent (Jayk Bernal et al, 2021). Though there are no clinical trials assessing the drug against Omicron, laboratory studies indicate Lagevrio is effective against it (Li et al, 2022; Takashita et al, 2022).
Lagevrio has some mild side-effects including diahorrea, nausea and dizziness. Because of its potential for mutagenicity, it shouldn’t be taken by pregnant or breastfeeding parents.
Paxlovid (nirmatrelvir + ritonavir)
Paxlovid is a dual-packaged drug combination of nirmatrelvir and ritonavir. Both are protease inhibitors that bind to a viral protease enzyme and stop its action. This deprives the virus of building blocks it needs to reproduce. Ritonavir also slows down the metabolism of nirmatrelvir, increasing its effectiveness. It was provisionally approved for use by adults in January 2022.
Like Lagevrio, the drug is recommended for people who are at high risk of hospitalisation from COVID-19 and have tested positive. To be effective, the course of drugs must begin within five days of the start of symptoms, though it is more effective if commenced within three days. The patient takes 300mg of nirmatrelvir and 100mg of ritonavir every 12 hours for five days.
There are no published clinical studies of Paxlovid’s effectiveness. However, Pfizer released a media statement in November 2021 citing results from phase II and III clinical trials indicating Paxlovid reduced the chance of hospitalisation and death of high risk COVID-19 patients by up to 90 per cent (Pfizer, 2021). Paxlovid is known to have some side effects including changes in taste, diahorrea, vomiting, hypertension and muscle pain.
Pregnant parents should avoid taking the drug.
Australian Government Department of Health (2 November 2021), Spikevax (Moderna), https://www.health.gov.au/initiatives-and-programs/covid-19-vaccines/approved-vaccines/moderna
Dunkle, L. M., Kotloff, K. L., Gay, C. L., Áñez, G., Adelglass, J. M., Barrat Hernández, A. Q., … & Dubovsky, F. (2021). Efficacy and Safety of NVX-CoV2373 in Adults in the United States and Mexico. New England Journal of Medicine, 386(6), 531-543.
Heath, P. T., Galiza, E. P., Baxter, D. N., Boffito, M., Browne, D., Burns, F., … & Toback, S. (2021). Safety and efficacy of NVX-CoV2373 Covid-19 vaccine. New England Journal of Medicine, 385(13), 1172-1183.
Jayk Bernal, A., Gomes da Silva, M. M., Musungaie, D. B., Kovalchuk, E., Gonzalez, A., Delos Reyes, V., … & De Anda, C. (2021). Molnupiravir for oral treatment of Covid-19 in nonhospitalized patients. New England Journal of Medicine, 386(6), 509-520.
Li, P., Wang, Y., Lavrijsen, M., Lamers, M. M., de Vries, A. C., Rottier, R. J., … & Pan, Q. (2022). SARS-CoV-2 Omicron variant is highly sensitive to molnupiravir, nirmatrelvir, and the combination. Cell Research, 1-3, https://doi.org/10.1038/s41422-022-00618-w
Takashita, E., Kinoshita, N., Yamayoshi, S., Sakai-Tagawa, Y., Fujisaki, S., Ito, M., … & Kawaoka, Y. (2022). Efficacy of Antibodies and Antiviral Drugs against Covid-19 Omicron Variant. New England Journal of Medicine, DOI: 10.1056/NEJMc2119407.
Pfizer (16 November 2021). Pfizer Seeks Emergency Use Authorization for Novel COVID-19 Oral Antiviral Candidate, https://www.pfizer.com/news/press-release/press-release-detail/pfizer-seeks-emergency-use-authorization-novel-covid-19