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Vaccine . Immunogenicity and safety of a fourth homologous dose of NVX-CoV2373

tetano

Editor, Senior Moderator
Vaccine


. 2023 Jun 2;S0264-410X(23)00612-6.
doi: 10.1016/j.vaccine.2023.05.051. Online ahead of print. Immunogenicity and safety of a fourth homologous dose of NVX-CoV2373

Katia Alves[SUP] 1 [/SUP], Joyce S Plested[SUP] 2 [/SUP], Shirley Galbiati[SUP] 3 [/SUP], Gordon Chau[SUP] 4 [/SUP], Shane Cloney-Clark[SUP] 5 [/SUP], Mingzhu Zhu[SUP] 6 [/SUP], Raj Kalkeri[SUP] 7 [/SUP], Nita Patel[SUP] 8 [/SUP], Kathy Smith[SUP] 9 [/SUP], Alex Marcheschi[SUP] 10 [/SUP], Susan Pfeiffer[SUP] 11 [/SUP], Heather McFall[SUP] 12 [/SUP], Gale Smith[SUP] 13 [/SUP], Gregory M Glenn[SUP] 14 [/SUP], Filip Dubovsky[SUP] 15 [/SUP], Raburn M Mallory[SUP] 16 [/SUP]; Novavax 2019nCoV-101 Study Group[SUP] 17 [/SUP]



Affiliations
Abstract

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has significantly reduced the efficacy of some approved vaccines. A fourth dose of NVX-CoV2373 (5 µg SARS-CoV-2 recombinant spike [rS] protein + 50 µg Matrix-M™ adjuvant; Novavax, Gaithersburg, MD) was evaluated to determine induction of cross-reactive antibodies to variants of concern. A phase II randomized study (NCT04368988) recruited participants in Australia and the United States to assess a primary series of NVX-CoV2373 followed by two booster doses (third and fourth doses at 6-month intervals) in adults 18-84 years of age. The primary series was administered when the SARS-CoV-2 ancestral strain was prevalent and the third and fourth doses while the Alpha and Delta variants were prevalent in AUS and US. Local/systemic reactogenicity was assessed the day of vaccination and for 6 days thereafter. Unsolicited adverse events (AEs) were reported. Immunogenicity was measured before, and 14 days after, fourth dose administration, using anti-spike serum immunoglobulin G (IgG) and neutralization assays against ancestral SARS-CoV-2 strain and Omicron sublineages. Among 1283 enrolled participants, 258 were randomized to receive the two-dose primary series, of whom 104 received a third dose, and 45 received a fourth dose of NVX-CoV2373. The incidence of local/systemic reactogenicity events increased after the first three doses of NVX-CoV2373 and leveled off after dose 4. Unsolicited AEs were reported in 9 % of participants after dose 4 (none of which were severe or serious). Anti-rS IgG levels and neutralization antibody titers increased following booster doses to a level approximately four-fold higher than that observed after the primary series, with a progressively narrowed gap in response between the ancestral strain and Omicron BA.5. A fourth dose of NVX-CoV2373 enhanced immunogenicity for ancestral and variant SARS-CoV-2 strains without increasing reactogenicity, indicating that updates to the vaccine composition may not be currently warranted.

Keywords: Booster; COVID-19; NVX-CoV2373; SARS-CoV-2 vaccine; Vaccine immunogenicity; Vaccine safety.

 
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