ABSTRACT
Covid-19 pandemic severely affected human health worldwide. The rapidly increasing COVID-19 cases and successive mutations of the virus have made it a major challenge for scientists to find the best and efficient drug/vaccine/strategy to counteract the virus pathogenesis. As a result of research in scientific databases, regulating the immune system and its responses with nutrients and nutritional interventions is the most critical solution to prevent and combat this infection. Also, modulating other organs such as the intestine with these compounds can lead to the vaccines' effectiveness. Marine resources, mainly algae, are rich sources of nutrients and bioactive compounds with known immunomodulatory properties and the gut microbiome regulations. According to the purpose of the review, algae-derived bioactive compounds with immunomodulatory activities, sulfated polysaccharides, and polyunsaturated fatty acids have a good effect on the immune system. In addition, they have probiotic/prebiotic properties in the intestine and modulate the gut microbiomes; therefore, they can increase the effectiveness of vaccines produced. Thus, they with respectable safety, immune regulation, and modulation of microbiota have potential therapeutic against infections, especially COVID-19. They can also be employed as promising candidates for the prevention and treatment of viral infections, such as COVID-19.