Salako Abideen, Musa Adesola, Ige Fehintola, Abdullahi Adam, James Ayorinde, Ekama Sabdat, Odubela Oluwatosin, Idigbe Ifeoma, Ajibaye Olusola, Mazharul Altaf, Adeneye Kazeem, Akinsolu Folahanmi T, Olojo Ifedola, Okwuraiwe Azuka, Egharevba Henry, Ekpenyong Magaret, Elemuwa Uchenna, Ezenyi Ifeoma, Bitrus Fraden, Odubela Olayemi, Oba Abdulrasheed, Idris Ganiu, Yusuf Jimoh, Akande Ibukun, Nwaiwu Stephine, Omale Louisa, Oyewunmi Oluwatobiloba, Agbabiaka Adedoyin, Eyinade Olajumoke, Ogunwale Joy, Garba Abdullah, Bello Yahya, Musa Baba, Ezejiofor Ogochukwu, Ejiro Ben, Iwalokun Bamidele, Rosenzweig Leah, Adigwe Obi, Adeyeye Christianah, Shuaib Faisal, Wicek Witold, Hamada Yohhei, Ezechi Oliver, Gupta Ravindra, Salako Babatunde
Nigerian Institute of Medical Research, Yaba, Lagos, Nigeria.
Department of Medicine and Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge, Cambridge, UK.
Sci Rep. 2025 Jul 29;15(1):27614. doi: 10.1038/s41598-025-06536-2.
Fractional dosing of vaccines is a viable strategy to extend COVID-19 vaccine supplies in resource-constrained settings. We did a triple-blinded, multi-site, randomized non-inferiority trial in Nigeria (PACTR202206754734018). Adults 18-65 years received full, half, or quarter primary doses of ChAdOx1 or Ad26.COV2.S, or full vs half doses of BNT162b2. Primary study outcome was seroconversion defined as ≥ 2.5-fold rise in anti-Spike IgG geometric-mean fold rise (GMFR) at day 28. A total of 1894 participants were enrolled between June 21, 2022, and January 25, 2023. 320 participants in the fractional dose group and 220 in the standard dose group completed follow-up and were included in the analysis. Seropositivity at baseline was high, at 68% (365/539). Seroconversion was comparable between standard and fractional doses (p = 0.822). For ChAdOx1, 31% achieved seroconversion at standard dose (16/52), 28% at half-dose (15/53), and 34% in quarter-dose (18/53). For Ad26.COV2.S, the proportions were 27% (28/105), 32% (22/68), and 30% (21/71) respectively. For BNT162b2, the proportions were 43% (27/63) and 39% (29/75) for standard- and half-dose. Serum neutralization showed ≥ twofold response across dosing. There were no serious adverse events. Fractional vaccine doses generated non-inferior immune responses compared to standard doses in the context of previous COVID-19.Protocol Registration: The protocol was registered with the Pan African Clinical Trials Registry (PACTR) PACTR202206754734018.
在资源有限的环境中，采用分剂量接种疫苗是扩大新冠疫苗供应的一种可行策略。我们在尼日利亚开展了一项三盲、多中心、随机非劣效性试验（注册号：PACTR202206754734018）。18至65岁的成年人分别接种了ChAdOx1或Ad26.COV2.S的全剂量、半剂量或四分之一剂量的初级疫苗，或BNT162b2的全剂量与半剂量疫苗。主要研究结局是血清转化，定义为在第28天时抗刺突蛋白IgG几何平均倍数增长（GMFR）升高≥2.5倍。2022年6月21日至2023年1月25日期间，共有1894名参与者入组。分剂量组的320名参与者和标准剂量组的220名参与者完成了随访并纳入分析。基线时的血清阳性率很高，为68%（365/539）。标准剂量和分剂量之间的血清转化率相当（p = 0.822）。对于ChAdOx1，标准剂量组的血清转化率为31%（16/52），半剂量组为28%（15/53），四分之一剂量组为34%（18/53）。对于Ad26.COV2.S，相应比例分别为27%（28/105）、32%（22/68）和30%（21/71）。对于BNT162b2，标准剂量组和半剂量组的比例分别为43%（27/63）和39%（29/75）。血清中和试验显示，各剂量组均有≥两倍的反应。未出现严重不良事件。在既往感染新冠病毒的背景下，分剂量疫苗产生的免疫反应与标准剂量相比不劣。试验方案注册：该方案已在泛非临床试验注册中心（PACTR）注册，注册号为PACTR202206754734018。
