AD	Alzheimer’s disease
BBB	Blood–brain barrier
CI	Confidence interval
CNS	Central nervous system
COVID-19	Coronavirus disease 2019
CSF	Cerebrospinal fluid
FiO2	Fractional inspired oxygen
GFAP	Glial fibrillary acidic protein
ICU	Intensive care unit
IQR	Interquartile range
NfL	Neurofilament light chain
NOS	Newcastle–Ottawa scale
PaO2	Partial pressure of oxygen
PRISMA	Preferred reporting items for systematic reviews and meta-analysis
RE	Random effect
SARS-CoV-2	Severe acute respiratory syndrome coronavirus-2
SD	Standard deviation
SMD	Standardized mean differences
UK	United Kingdom
USA	United States of America