Schultz Bárbara M, Melo-González Felipe, Duarte Luisa F, Gálvez Nicolás Ms, Pacheco Gaspar A, Soto Jorge A, Berríos-Rojas Roslye V, González Liliana A, Moreno-Tapia Daniela, Rivera-Pérez Daniela, Ríos Mariana, Vázquez Yaneisi, Hoppe-Elsholz Guillermo, Vallejos Omar P, Iturriaga Carolina, Urzua Marcela, Navarrete María S, Rojas Álvaro, Fasce Rodrigo, Fernández Jorge, Mora Judith, Ramírez Eugenio, Gaete-Argel Aracelly, Acevedo Mónica, Valiente-Echeverría Fernando, Soto-Rifo Ricardo, Weiskopf Daniela, Grifoni Alba, Sette Alessandro, Zeng Gang, Meng Weining, González-Aramundiz José V, González Pablo A, Abarca Katia, Kalergis Alexis M, Bueno Susan M
medRxiv. 2022 Feb 7:2021.11.16.21266350. doi: 10.1101/2021.11.16.21266350.
CoronaVac is an inactivated SARS-CoV-2 vaccine approved by the World Health Organization. Previous studies reported increased levels of neutralizing antibodies and specific T cells two- and four-weeks after two doses of CoronaVac , but the levels of neutralizing antibodies are reduced at six to eight months after two doses. Here we report the effect of a booster dose of CoronaVac on the anti-SARS-CoV-2 immune response generated against variants of concern (VOC) Delta and Omicron in adults participating in a phase 3 clinical trial in Chile.
Volunteers immunized with two doses of CoronaVac in a four-week interval received a booster dose of the same vaccine between twenty-four and thirty weeks after the 2nd dose. Four weeks after the booster dose, neutralizing antibodies and T cell responses were measured. Neutralization capacities and T cell activation against VOC Delta and Omicron were detected at four weeks after the booster dose.
We observed a significant increase in neutralizing antibodies at four weeks after the booster dose. We also observed an increase in CD4 T cells numbers over time, reaching a peak at four weeks after the booster dose. Furthermore, neutralizing antibodies and SARS-CoV-2 specific T cells induced by the booster showed activity against VOC Delta and Omicron.
Our results show that a booster dose of CoronaVac increases the anti-SARS-CoV-2 humoral and cellular immune responses in adults. Immunity induced by a booster dose of CoronaVac is active against VOC, suggesting an effective protection.
科兴新冠疫苗是一种经世界卫生组织批准的新型冠状病毒灭活疫苗。此前的研究报告称，接种两剂科兴新冠疫苗后两周和四周，中和抗体水平和特异性T细胞水平有所升高，但两剂接种后六至八个月，中和抗体水平会下降。在此，我们报告了在智利参与一项3期临床试验的成年人中，一剂科兴新冠疫苗加强针针对值得关注的变异株（VOC）德尔塔和奥密克戎产生的抗新型冠状病毒免疫反应的效果。
间隔四周接种两剂科兴新冠疫苗的志愿者在第二剂接种后24至30周之间接受了同一疫苗的一剂加强针。加强针接种四周后，检测中和抗体和T细胞反应。在加强针接种四周后检测针对VOC德尔塔和奥密克戎的中和能力和T细胞活化情况。
我们观察到加强针接种四周后中和抗体显著增加。我们还观察到CD4 T细胞数量随时间增加，在加强针接种四周后达到峰值。此外，加强针诱导的中和抗体和新型冠状病毒特异性T细胞对VOC德尔塔和奥密克戎具有活性。
我们的结果表明，一剂科兴新冠疫苗加强针可增强成年人的抗新型冠状病毒体液免疫和细胞免疫反应。一剂科兴新冠疫苗加强针诱导的免疫力对VOC具有活性，表明具有有效的保护作用。
