Prior COVID-19 vaccination and cognitive outcomes after SARS-CoV-2 infection: a mini-review

COVID-19 infection has been frequently associated with cognitive deficits that persist for months after the acute phase, but the impact of vaccination on preventing these deficits remains uncertain. Evidence suggests that immunization reduces the incidence and severity of post-COVID symptoms, yet few studies have evaluated its influence on cognition using objective measures. To address this gap, a mini-review was conducted using a systematic search strategy, following PRISMA recommendations where applicable, with a protocol registered in PROSPERO (CRD42025636772). Searches were carried out in the PubMed/MEDLINE and Scopus databases, and eligible studies were those that assessed cognition using objective measures and compared vaccinated and unvaccinated individuals at the time of infection. A total of 1,796 records were identified, of which only five met the inclusion criteria. The included studies varied considerably in cognitive assessment tools, study designs, and sample sizes. Four of the five studies found no association between prior vaccination and cognitive deficits, whereas the only study that identified a subtle difference among individuals who had received at least two doses of the vaccine had a substantially larger sample than all the others combined. Methodological inconsistencies in cognitive assessment, variability in the definitions of vaccination status, and the lack of stratification by specific cognitive domains limit the interpretation of the current findings. Although vaccination may play a role in protecting against cognitive deficits following COVID-19 infection, the evidence remains limited and inconclusive. Further studies with standardized definitions of vaccination status and comprehensive objective assessments are needed to clarify this relationship.