Name: NVX-CoV2373

Type: Protein vaccine (nanoparticle-based vaccine)

Developer: Novavax

Likely doses/timing: 2 doses (21 days apart)

Doses for Australia: 51 million doses will be made available in Australia during 2021

Manufacturing: Doses for Australia will be manufactured in several locations across Europe and Asia

Storage: Can be stored, transported and handled at standard refrigerator temperatures (2-8°C)


The Novavax COVID-19 vaccine (NVX-CoV2373) was created using Novavax’ recombinant nanoparticle technology which contains the full length SARS-CoV-2 spike protein and Novavax’ patented Matrix-M1 adjuvant (an additional vaccine component that boosts the immune response).

Novavax is a biotechnology company from the USA. Their nanoparticle and Matrix-M1 technology has been previously studied in Phase 3 trials of their quadrivalent influenza vaccine, NanoFlu.

Clinical trials

Pre-clinical trials were conducted in baboons and mice. In animal models, the vaccine induced high levels of anti-spike antibodies and neutralising antibodies, which exceeded the responses measured in humans recovered from natural COVID-19 infection.

Phase 1 clinical trials were conducted in 131 healthy adults, beginning in May 2020. Early clinical trials were performed in Melbourne and Brisbane, Australia, as well as in the USA. Phase 1 results were released in September 2020. This study assessed the safety and immunogenicity of two doses (5-μg and 25-μg) with or without Matrix-M1 adjuvant in healthy adults aged 18 to 59 years, compared to placebo. The phase 2 clinical trials expanded the age of participants to include those aged 60-84 years and results are still pending.

Phase 3 trials are underway in the UK and enrolment of 15,000 participants was completed in November 2020. Interim data is expected in the first quarter of 2021. More large-scale clinical trials are underway or planned for other countries in late 2020 and early 2021, including South Africa, USA and Mexico. These Phase 3 trials will include 30,000 participants overall.

Safety profile

No serious adverse events or adverse events of special interest were reported in Phase 1 trials. Overall reactogenicity was largely absent or mild and the average duration was two days or less for both doses. After first vaccination, local reactions only occurred in 4-16% of participants that received NVX-CoV2373 (the rate of reaction varied for each subgroup; depending on dose given or whether adjuvant was given). Systemic reactions occurred in 4-32% of participants, depending on the subgroup. Common side effects included headache, fatigue and myalgia. After the second vaccination, local and systemic reactogenicity were absent or mild in the majority of participants in all subgroups.


Phase 1 results showed NVX-CoV2373 elicited robust antibody responses which were greater than the responses measured in people recovered from natural COVID-19 infection. All participants developed antibodies after a single dose. All participants developed neutralizing antibodies after the second dose. The Matrix-M1 adjuvant was dose sparing; in those receiving NVX-CoV2373 with the Matrix-M1 adjuvant, immunogenicity results were comparable in both low and high dose groups. The Matrix-M1 adjuvant also induced robust polyfunctional CD4+ T-cell responses.

Vaccine efficacy

Interim data regarding vaccine efficacy from the UK’s Phase 3 trials are expected in the first quarter of 2021, noting the high rates of COVID-19  being seen globally may lead to early completion of these event driven trials.


Authors: Daniela Say (MVEC Immunisation Fellow) and Nigel Crawford (Director SAEFVIC, Murdoch Children’s Research Institute)

Date: January 2021

Materials in this section are updated as new information and vaccines become available. The Melbourne Vaccine Education Centre (MVEC) staff regularly reviews materials for accuracy.

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