Table 1. Advancing Diagnosis and Treatment.

Personalized Microbiome Therapies	The recognition that the gut microbiome varies significantly between individuals has led to the exploration of personalized microbiome therapies. These therapies could involve tailored probiotic or prebiotic interventions, designed based on an individual’s specific microbiome profile, to restore microbial balance and alleviate Long COVID symptoms. Personalized diets that target specific microbial communities might also be developed to support gut health and reduce inflammation.
Advanced Omics Technologies	Integrating advanced omics technologies, such as metagenomics, metabolomics, and transcriptomics, into Long COVID research offers a powerful approach to understanding the complex interactions between the gut microbiome and the host. Metagenomics can provide detailed insights into the composition and functional potential of the gut microbiome, while metabolomics can reveal the metabolic products of microbial activity and their effects on host physiology. Transcriptomics can help uncover how gut-derived signals influence gene expression in different tissues, including the immune system and the brain.
Microbiome-Immune Interactions	Emerging research is also focusing on the intricate interactions between the gut microbiome and the immune system in Long COVID. Understanding how specific gut microbes modulate immune responses could lead to novel immunomodulatory therapies that target the gut to treat systemic inflammation and autoimmunity associated with Long COVID.
Gut-Brain Axis Studies	The gut-brain axis is another area of intense interest, particularly in relation to the neuropsychiatric symptoms of Long COVID. Research is increasingly focusing on how gut microbiome alterations influence brain function and behavior through serotonin production, vagal nerve signaling, and inflammatory pathways. Studies in this area could lead to new treatments that address both gastrointestinal and neurological symptoms of Long COVID.
Longitudinal Cohort Studies	To address the existing research gaps, future studies should include large, well-characterized longitudinal cohorts of COVID-19 patients. These studies would ideally track participants from the acute phase of infection through recovery and beyond, capturing detailed data on microbiome composition, immune function, and clinical outcomes. Such research could identify early indicators of Long COVID, reveal potential therapeutic targets, and inform the development of prevention strategies.