NVX-CoV2373 vaccine protects against COVID-19

Administering two doses of NVX-CoV2373 (Novavax) vaccine lowers the occurrence of virologically confirmed symptomatic mild, moderate, or severe COVID-19 in healthy adults, according to data from the 2019nCoV-302* study.

The NVX-CoV2373 vaccine contains 5 μg of recombinant nanoparticle spike protein and 50 μg of Matrix-M adjuvant against SARS-CoV-2.

“Early clinical data from studies of the NVX-CoV2373 … have shown that the vaccine was safe and associated with a robust immune response in healthy adult participants,” said the researchers. [N Engl J Med 2020;383:2320-2332; https://www.medrxiv.org/content/10.1101/2021.02.26.21252482v1]

“[However,] additional data were needed regarding the efficacy, immunogenicity, and safety of this vaccine in a larger population,” they noted.

Hence, the researchers conducted an observer-blinded, placebo-controlled, phase III trial involving 14,039 healthy individuals (mean age 56 years, 51.6 percent male) who were recruited from 33 sites in the UK between September 28 and November 28, 2020. Participants were randomized to receive either two intramuscular injections of NVX-CoV2373 (n=7,020) or placebo (n=7,019), administered 21 days apart. [N Engl J Med 2021;385:1172-1183]

At ≥7 days after the second dose, individuals in the NVX-CoV2373 group had a lower incidence of virologically confirmed symptomatic COVID-19 than the placebo group (10 vs 96 individuals; 6.53 vs 63.43 per 1,000 person-years, respectively), showing a high vaccine efficacy of 89.7 percent.

Among the 10 participants infected with COVID-19 in the NVX-CoV2373 group, eight individuals were infected by the B.1.1.7 (alpha) variants and one individual was infected by a non-B.1.1.7 variant, while one viral strain was unidentified. “[Of note,] this ongoing trial was initiated during the period in which the B.1.1.7 variant was starting to circulate more widely … outside the UK and was the most widespread strain reported in the US,” the researchers highlighted.

In a post hoc analysis, NVX-CoV2373 vaccine efficacy was 86.3 and 96.4 percent against the B.1.1.7 and non-B.1.1.7 variants, respectively. The efficacy against the non-B.1.1.7 strains was similar to the reported efficacy of 95.0 percent for the BNT161b2 mRNA vaccine (BioNTech/Pfizer) and 94.1 percent for the mRNA-1273 vaccine (Moderna). [N Engl J Med 2021;384:403-416; N Engl J Med 2020;383:2603-2615]

Local adverse events (AEs), such as injection-site tenderness and pain, occurred more frequently in the NVX-CoV2373 group than the placebo group after the first and second dose (57.6 percent vs 17.9 percent and 45.7 percent vs 36.3 percent, respectively).

The NVX-CoV2373 group also demonstrated a higher incidence of systemic AEs, including fatigue, headache, and muscle pain, compared with the placebo group after two doses (45.7 percent vs 36.3 percent [first dose] and 64.0 percent vs 30.0 percent [second dose]).

“[Nevertheless, no cases of] deaths were attributed to the receipt of the [NVX-CoV2373] vaccine … Reactogenicity was generally mild or moderate, and reactions were less common and milder in older participants and more common after the second dose,” the researchers noted.

“Prevention of severe disease (including hospitalization, intensive care admission, and death) is an important objective of a vaccination programme. The two-dose regimen of the NVX-CoV2373 vaccine … conferred 89.7 percent protection against SARS-CoV-2 infection and showed high efficacy against the B.1.1.7 variant, … [which was] similar to that reported for other licensed COVID-19 vaccines,” said the researchers.

“The results of this trial provide further evidence that immunization with a protein-based, adjuvanted vaccine such as NVX-CoV2373 can prevent COVID-19 caused by either B.1.1.7 or non-B.1.1.7 variants,” they added.

*2019nCoV-302: A phase 1/2/3, placebo-controlled, randomized, observer-blind, dose-finding study to evaluate the safety, tolerability, immunogenicity, and efficacy of SARS-CoV-2 RNA vaccine candidates against COVID-19