The immune system's job is to defend the person from harmful pathogens. The immune response is influenced by a variety of factors, and a healthy diet is crucial for promoting immunity. Aging adults, especially those who are fragile, obese, malnourished, or who consume insufficient amounts of micronutrients, can have reduced immunity. Due to immune system deficits brought on by inadequate nutrition, people are more susceptible to infections, which can worsen or even prove fatal. The detrimental effects of inadequate nutrition on the immune system, especially its inflammatory component, may be one of the explanations for the greater risk of more severe consequences from SARS-CoV-2 infection reported in older individuals and those who are obese. Studies on specific micronutrients, such as zinc and vitamin D, suggest roles in lowering the severity of SARS-CoV-2 infection. A diverse gut microbiota, which supports the immune system, can be encouraged through healthy eating. Assuring strong responses to vaccinations is also based on the significance of nutrition in promoting the immune response. For the fight against SARS-CoV-2, there are numerous lessons to be learned from the research on immunity and nutrition.