Chronic infection with human CMV may contribute to poor vaccine efficacy in older adults. We assessed the effects of CMV serostatus on Ab quantity and quality, as well as cellular memory recall responses, after two and three SARS-CoV-2 mRNA vaccine doses, in older adults in assisted living facilities. CMV serostatus did not affect anti-Spike and anti-receptor-binding domain IgG Ab levels, nor neutralization capacity against wild-type or β variants of SARS-CoV-2 several months after vaccination. CMV seropositivity altered T cell expression of senescence-associated markers and increased effector memory re-expressing CD45RA T cell numbers, as has been previously reported; however, this did not impact Spike-specific CD4+ T cell memory recall responses. CMV-seropositive individuals did not have a higher incidence of COVID-19, although prior infection influenced humoral immunity. Therefore, CMV seropositivity may alter T cell composition but does not impede the durability of humoral protection or cellular memory responses after SARS-CoV-2 mRNA vaccination in older adults.
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