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

Updated: Sep 24, 2021
  • Author: David J Cennimo, MD, FAAP, FACP, FIDSA, AAHIVS; Chief Editor: John L Brusch, MD, FACP  more...
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  • Phase 3 trial (PREVENT-19) demonstrated 90.4% overall efficacy and 100% protection against moderate-to-severe disease  
  • Crossover studies initiated in ongoing trials in South Africa, the United Kingdom, and the United States in March/April 2021 to ensure all participants receive vaccine 
  • Trial in adolescents aged 12-17 years has enrolled 2,248 participants as of mid-June 2021 with enrollment goal of 3,000 across 75 US sites
  • Refrigerate (2-8ºC) for shipping and storage; solution for IM injection  

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. It is administered as a 2-dose series 21 days apart. 

The PREVENT-19 phase 3 clinical trial demonstrated overall efficacy of 90.4%. Results are based on 77 cases of symptomatic COVID-19 that investigators observed among trial participants from January 25 through April 30, 2021. There were 63 cases among the approximately 10,000 participants who received placebo and 14 cases among the approximately 20,000 participants who received the investigational vaccine. Of the 63 COVID-19 cases in the placebo group, investigators classified 10 as moderate and 4 as severe. There were no cases of moderate or severe disease in the investigational vaccine group. [39]   

The phase 3 trial in the United Kingdom has completed enrollment and the phase 2b trial in South Africa has reported final results. [40]  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 [40]

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

  • Final analysis based on 106 cases (96 placebo, 10 in NVX-CoV2373) 
  • 101 cases were mild or moderate; 5 were severe (placebo group); 4 of the 5 attributed to B.1.1.7 variant (UK strain)  
  • Calculated efficacy UK strain: 86.3%
  • Calculated efficacy original strain: 96.4%

South Africa phase 2b results [41]

Among over 6000 participants who underwent screening, 4,387 patients received at least 1 injection of vaccine or placebo 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. 

  • 60.1% efficacy for the prevention of mild, moderate, and severe COVID-19 disease was observed in the study population that was baseline seronegative and HIV-negative
  • 49.4% overall efficacy with results from both patient populations (ie, HIV positive and negative) 
  • 100% protection against severe disease observed, including all hospitalization and death

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