Beyond adaptive immunity: induction of trained immunity by COVID-19 adenoviral vaccines

Abstract

The COVID-19 pandemic, caused by the SARS-CoV-2 coronavirus, has resulted in much human suffering and societal disruption. The ChAdOx1 nCoV-19 vaccine against COVID-19 has had a crucial role in the fight against the pandemic. While ChAdOx1 nCoV-19 has been shown to induce adaptive B and T cell responses, which protect against COVID-19, in this issue of the JCI, Murphy et al. show that this vaccine also induces trained innate immunity. This finding contributes to a better understanding of the complex immunological effects of adenoviral-based vaccines, provides the possibility of clinically relevant heterologous effects of these vaccines, and suggests that other adenoviral-based vaccines may induce trained immunity.

Figure 1. The ChAdOx1 nCoV-19 vaccine induces both classical adaptive immunity and trained immunity against SARS-CoV-2.

Within a few weeks of ChAdOx1 nCoV-19 vaccination, T cells and B cells collaborate to generate specific antibodies and activated cells that protect against SARS-CoV-2 infection. Up to three months after vaccination, monocytes show increased frequency in the peripheral blood. They also show increased expression of activation markers, costimulatory molecules, glycolysis-associated enzymes, and cytokines. Increases in these factors are likely a consequence of epigenetic and metabolic reprogramming.