Post by The Lancet Infectious Diseases

🆕 A new phase 4 clinical trial in young Singaporean adults assesses whether high-dose recombinant quadrivalent influenza vaccines (QIV-R) are more immunogenic than standard-dose egg-grown (QIV-E) and cell-grown (QIV-C) vaccines among frequent and infrequent vaccinees. 📊Sheena G Sullivan and colleagues conducted a randomized, controlled, single-centre, single-season, double-blind phase 4 clinical trial. Participants were randomised 1:1:1 to recombinant (QIV-R, high-dose, 45 µg of each antigen), cell-grown (QIV-C, standard-dose, 15 µg of each antigen), and egg-grown (QIV-E, standard-dose, 15 µg of each antigen) quadrivalent influenza vaccines in healthy adults (n=366; aged 21–49 years), stratified by the number of vaccines received in the preceding 5 years as infrequent (zero or one) and frequent (three or more), from the National Centre for Infectious Diseases, Singapore. The primary outcome was geometric mean titre (GMT) against egg-grown and cell-grown A(H3N2) vaccine viruses at 14 days post-vaccination, estimated by linear regression adjusted for vaccination history and baseline titre and analysed in the per-protocol set. Authors found that post-vaccination GMTs against cell grown A(H3N2) were 2·9-fold higher (95% CI 2·2–3·8) following QIV-R (GMT 100, 95% CI 84–120) compared with QIV-C (35, 29–43; p<0·0001) or QIV-E (36, 29–43; p<0·0001). Adjusted GMTs were lower among frequent compared with infrequent vaccinees who received QIV-E (GMT 25, 95% CI 19–34 vs 50, 38–66) or QIV-C (24, 18–32 vs 53, 40–70) but were similar for frequent and infrequent vaccinees who received QIV-R (93, 70–120 vs 110, 84–150). 💡These findings indicate that high-dose QIV-R provides a potential solution for maintaining immunogenicity and in turn effectiveness of annually administered influenza vaccine. Further work is required to determine whether the benefits of high-dose QIV-R are also realised for older adults, whether gains in immunogenicity from QIV-R are sustained over multiple seasons, and how the boost to immunogenicity for repeat vaccinees translates to improved vaccine effectiveness. Read the full paper here: https://bit.ly/4mxfj21 #influenza, #vaccines, #immunogenicity, #repeated vaccination Xuan Ying Poh, Stephany Sanchez-Ovando, A Jessica Hadiprodjo, Louise Carolan, Yi Qing Chin, Suma Rao, Stephanie Sutjipto, Joseph Lim, Desiree Anthony, Sapna P Sadarangani, Ian G Barr, Barnaby Young, Annette Fox