PMID- 37198021 OWN - NLM STAT- MEDLINE DCOM- 20230605 LR - 20231213 IS - 1873-2518 (Electronic) IS - 0264-410X (Print) IS - 0264-410X (Linking) VI - 41 IP - 25 DP - 2023 Jun 7 TI - Immunogenicity and safety of a single booster dose of NVX-CoV2373 (TAK-019) in healthy Japanese adults who had previously received a primary series of COVID-19 mRNA vaccine: Primary analysis report of a phase 3 open-label trial. PG - 3763-3771 LID - S0264-410X(23)00519-4 [pii] LID - 10.1016/j.vaccine.2023.05.001 [doi] AB - BACKGROUND: We evaluated the immunogenicity and safety of a booster dose of NVX-CoV2373 in Japanese adults who had completed a primary series of COVID-19 mRNA vaccine 6-12 months previously. METHODS: This single-arm, open-label, phase 3 study, conducted at two Japanese centres, enrolled healthy adults >/= 20 years old. Participants received a booster dose of NVX-CoV2373. The primary immunogenicity endpoint was non-inferiority (lower limit of the 95 % confidence interval [CI] >/= 0.67) of the geometric mean titre (GMT) ratio of titres of serum neutralizing antibodies (nAbs) against the SARS-CoV-2 ancestral strain 14 days after booster vaccination (day 15) in this study, compared with those 14 days after the second primary NVX-CoV2373 vaccination (day 36) in the TAK-019-1501 study (NCT04712110). Primary safety endpoints included local and systemic solicited adverse events (AEs) up to day 7 and unsolicited AEs up to day 28. RESULTS: Between 15 April 2022 and 10 May 2022, 155 participants were screened and 150, stratified by age (20-64 years old [n = 135] or >/= 65 years old [n = 15]), received an NVX-CoV2373 booster dose. The GMT ratio between titres of serum nAbs against the SARS-CoV-2 ancestral strain on day 15 in this study and those on day 36 in the TAK-019-1501 study was 1.18 (95 % CI, 0.95-1.47), meeting the non-inferiority criterion. Following vaccination, the proportion of participants who reported local and systemic solicited AEs up to day 7 was 74.0 % and 48.0 %, respectively. The most common local and systemic solicited AEs were tenderness (102 participants [68.0 %]) and malaise (39 participants [26.0 %]), respectively. Seven participants (4.7 %) reported unsolicited AEs between vaccination and day 28; all were severity grade