Name: NVX-CoV2373 (Novavax COVID-19 vaccine)

Type: Protein vaccine (nanoparticle-based vaccine)

Developer: Novavax

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

Doses for Australia: If granted provisional registration by the Therapeutic Goods Administration (TGA), 51 million doses will be made available for 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).

Background

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

On January 19, 2021 Novavax was granted provisional determination by the TGA for their COVID-19 vaccine.

Immunogenicity

Pre-clinical trials of Novavax COVID-19 vaccine candidate 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 aged 18-59 years in Australia and the United States of America (USA). The study assessed the safety and immunogenicity of two doses (low dose 5-μg and high dose 25-μg) with or without Matrix-M1 adjuvant in healthy adults aged 18 to 59 years, compared to a placebo. Overall the vaccine elicited a good immune response, with immunogenicity comparable in both low and high dose groups. An enhanced immune response was seen in the adjuvant group.

A phase 2 trial in Australia and the USA expanded the age of participants to include 1,288 participants aged 18-84. Results of this study indicated that a two-dose regimen of 5-µg NVX-CoV2373 administered 21 days apart was the optimal vaccine dose to proceed to phase 3 trials.

Safety profile

Preliminary phase 3 results indicate that side effects following administration of the Novavax COVID-19 vaccine have been generally mild to moderate, and short-lived. Injection site pain and tenderness, as well as fatigue, headache and muscle pain were the most commonly reported side effects.. The incidence of serious adverse events was low, and reported in similar numbers in both the vaccine arm and placebo group.

Vaccine efficacy

United Kingdom (UK)

Phase 3 clinical trials in the UK enrolled more than 15,000 participants aged between 18-84 years of age. Preliminary results demonstrated an overall efficacy of 89.7%.  It was 96.4% efficacious against the original COVID-19 strain and 86.3% against the circulating Alpha strain. There was 100% protection against severe disease (hospitalisation and death) for both strains.

South Africa

A phase 2b clinical trial  conducted in South Africa included 4387 participants (HIV-negative and HIV-positive). The vaccine demonstrated 49.4% efficacy in preventing COVID-19 disease caused by the Beta variant for all participants. This increased to 60.1% efficacy for the HIV-negative only cohort. All COVID-19 infections in the vaccine group were mild/moderate, and there were no severe cases. Serious adverse events were rare and unrelated to the vaccine.

United States of America (USA)

Approximately 30,000 participants were enrolled in PREVENT-19 (PRE-fusion protein subunit Vaccine Efficacy Novavax Trial COVID-19), a phase 3 trial in Mexico and the USA. The vaccine demonstrated 90.4% efficacy overall for preventing symptomatic COVID-19 disease, with 100% protection against moderate and severe disease. For “high-risk” populations (defined as over age 65, under age 65 with certain comorbidities or having life circumstances with frequent COVID-19 exposure) the vaccine was reported to be 91.0% efficacious.

Further studies

Paediatric clinical trials

Children were not included in the initial Novavax COVID-19 vaccine clinical trials due to the decrease in severity of symptoms experienced by children infected with SARS-CoV-2 compared with infected adults. Various clinical trials are currently underway to determine the safety and efficacy of Novavax COVID-19 vaccine in the paediatric population.

For further information refer to MVEC: COVID-19 vaccination in children.

Mixed vaccine schedules

Clinical trials are currently underway to evaluate the immunogenicity and reactogenicity of combining the Novavax vaccine with different COVID-19 vaccine brands to complete a vaccine course.

For further information refer to MVEC: COVID-19 mixed vaccine schedules.

Clinical trial crossover

In April 2021, Novavax announced that they will introduce crossover arms for all three trials in the UK, South Africa and USA. Participants in the UK and the US who were given the placebo in the initial trial will now be offered the active vaccine. In South Africa all participants will be offered the active vaccine, meaning that those who previously received the placebo will be vaccinated and those who received the vaccine previously will receive a booster dose. This will give all participants the opportunity to receive protection with ongoing follow up. All participants will remain blinded.

Resources

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

Reviewed by: Rachael McGuire, (MVEC Education Nurse Coordinator), Francesca Machingaifa (MVEC Education Nurse Coordinator) and Davina Buntsma (MVEC Immunisation Fellow)

Date: June 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.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family’s personal health. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult a healthcare professional.