Novavax, the recombinant nanoparticle Covid-19 vaccine.
The US biotechnology company Novavax has developed a coronavirus vaccine, called NVX-CoV2373, which differs from the three vaccines already in use in the United States, as it is based on what is called recombinant nanoparticle technology and Novavax's adjuvant, Matrix-M1, to stimulate an immune response.
The two mRNA vaccines authorized for use in the United States, from Pfizer/BioNTech and Moderna, use genetic material to stimulate an immune response, while Johnson & Johnson's single-shot vaccine uses a weakened common cold virus as a vector to deliver the genetic instructions.
Novavax is made up of nanoparticles obtained by recombinant technology of infectious baculovirus in Sf9 insect cells; to which the Matrix-M1 adjuvant based on saponins is added.
This Novavax saponin-based adjuvant, which enhances immune responses and allows for a reduction in vaccine dosage, is composed of 40-nanometer saponin particles extracted from the bark of Quillaja saponaria Molina along with cholesterol and phospholipids.
NVX-CoV2373 is a recombinant nanoparticle vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), composed of full trimeric SARS-CoV-2 spike glycoproteins and the Matrix-M1 adjuvant. According to Novavax, this coronavirus vaccine has an overall efficacy of 90.4% in a Phase 3 trial conducted in the United States and Mexico. Seventy-seven cases were observed: 63 in the placebo group and 14 in the vaccine group. All cases observed in the vaccine group were mild. In the placebo group, ten moderate and four severe cases were observed, in which the vaccine showed a 100% efficacy (95% CI: 87.0, 100) against moderate or severe disease.
The vaccine also showed success among “high-risk” populations (those over 65 years of age, those under 65 with certain comorbidities, or those with frequent exposure to COVID-19). Therefore, among these at-risk groups, the vaccine's efficacy was 91.0% (95% CI: 83.6, 95.0), with 62 cases of COVID-19 in the placebo group and 13 cases of COVID-19 in the vaccine group.
The study also met its second key endpoint and demonstrated 100% efficacy (95% CI: 80.8, 100) against variants not considered of interest or concern. Of the sequenced cases, 35 (65%) were variants of concern, 9 (17%) were variants of interest, and 10 (19%) were other variants.
Against variants of concern or interest, which represented 82% of cases, the vaccine efficacy was 93.2% (95% CI: 83.9, 97.1), achieving a key exploratory endpoint of the study. Thirty-eight of the variant cases of concern or interest were in the placebo group and six in the vaccine group.
When assessing reactogenicity, 7 days after the first and second doses, the most common local symptoms were pain and tenderness at the injection site. (generally of mild or moderate intensity). These symptoms only lasted three days . Fatigue, headache, and muscle pain were the most frequent systemic symptoms and lasted less than two days.
An important fact in relation to other vaccines and their use in mass vaccination campaigns is that the presentation is in liquid formulation, to mix antigen and adjuvant, and the storage can be carried out between 2ºC and 8ºC.
Further analyses of the trial are underway and will be submitted to peer-reviewed journals for publication. The company plans to apply for emergency use authorization for its vaccine in the United States in the third quarter of this year and is on track to manufacture approximately 100 million doses per month by the end of the third quarter.
Following the presentation of these results, the company stated that it plans to seek approval from the country's FDA. If successful, it would be the fourth US vaccine, joining those from Pfizer, Moderna, and Janssen.
Novavax will also seek approval for its vaccine in Europe from the European Medicines Agency (EMA). If approved, it would become the fifth vaccine approved by the EMA after Pfizer, Moderna, AstraZeneca, and Janssen.
Ramona Ávila Núñez, PhD