Evaluation of the Humoral Immune Response Following Two Doses of a Coronavirus Disease 2019 Vector-Based Vaccine During the Initial Rollout in Bangladesh

This study demonstrated that ChAdOx1 elicits robust antibody responses in the majority of individuals, with significantly stronger reactions observed among those with prior COVID-19 infection. Moreover, it provides effective protection against recurrent infection in this population, provided that a SARS-CoV-2 IgG titer is sustained above the minimum threshold of 359.5 BAU/mL. Nevertheless, additional research is warranted to characterize the SARS-CoV-2 IgG response across diverse populations receiving heterologous or multi-regimen vaccination strategies.