ACE2	Angiotensin-converting enzyme 2
COVID-19	Coronavirus disease
CRP	C-reactive protein
GABA	Gamma-aminobutyric acid
IBD	Inflammatory bowel disease
IBS	Irritable bowel syndrome
IgA	Immunoglobulin A
IL-6	Interleukin-6
IL-8	Interleukin-8
LAB	Lactic acid bacteria
MERS-CoV	Middle East respiratory syndrome coronavirus
NAC	N-acetyl-cysteine
PICO	Population, Intervention, Comparator, Outcome
PRISMA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
PRN	Pro re nata
SARS-CoV	Severe acute respiratory syndrome coronavirus
SCFAs	Short-chain fatty acids
TNF-α	Necrosis factor-alpha
WHO	World Health Organization