What is the NVX-CoV2373 coronavirus disease 2019 (COVID-19) vaccine?

Updated: Feb 28, 2021
  • Author: David J Cennimo, MD, FAAP, FACP, AAHIVS; more...
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  • Subunit vaccine
  • Dose: 2 injections 21 days apart

NVX-CoV2373 (Novavax) is engineered using recombinant nanoparticle technology from SARS-CoV-2 genetic sequence to generate full-length, prefusion spike (S) protein. This is combined with an adjuvant (Matrix-M). Results of preclinical studies showed that it binds efficiently with human receptors targeted by the virus.

Phase 1/2 trials initiated in May 2020. Phase 1 data in healthy adults showed the adjuvanted vaccine induced neutralization titers that exceeded responses in convalescent serum from mostly symptomatic patients with COVID-19. [18]   

The phase 3 trial in the United Kingdom has completed enrollment and the phase 2b trial in South Africa have reported preliminary results. [13]  

The US and Mexico phase 3 trial (PREVENT-19) was initiated in December 2020. Enrollment of approximately 30,000 participants was completed mid-February 2021. Results of these trials are timely, as new circulating viral variants in The UK and South Africa have emerged during the trials.  

UK phase 3 results [13]

The study enrolled more than 15,000 adults aged 18-84 years, including 27% older than 65 years. 

  • First interim analysis based on 62 cases (56 placebo, 6 in NVX-CoV2373) 
  • Point estimate of vaccine efficacy: 89.3% (95% CI: 75.2-95.4)
  • 61 cases were mild or moderate; 1 was severe (placebo group)  
  • UK variant detected in over 50% of PCR-confirmed symptomatic cases (preliminary analysis); 32 UK variant, 24 nonvariant, 6 unknown 
  • Calculated efficacy UK strain: 85.6%
  • Calculated efficacy original strain: 95.6%

South Africa phase 2b results [13]

This study enrolled over 4,400 patients beginning in August 2020, with COVID-19 cases counted from September through mid-January. During this time, the triple mutant variant, containing 3 critical mutations in the RBD and multiple mutations outside the RBD, was widely circulating in South Africa.

  • 60% efficacy (95% CI: 19.9-80.1) for the prevention of mild, moderate, and severe COVID-19 disease was observed in the 94% of the study population that was HIV-negative
  • 29 cases observed in the placebo group and 15 in the vaccine group; 1 severe case occurred in the placebo group and all other cases were mild or moderate
  • 49.4% overall efficacy (95% CI: 6.1-72.8) with results from both patient populations (ie, HIV positive and negative) 
  • South African variant: 27 of 44 COVID-19 events; of these, 92.6% (25 out of 27 cases) were the South Africa escape variant

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