Studies have shown that higher levels of omega-3 fatty acids, specifically DHA, may be associated with a lower risk of contracting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and experiencing adverse outcomes from coronavirus disease 2019 (COVID-19), including hospitalization and death. 

According to a study conducted in the UK Biobank cohort, higher levels of DHA in the blood were associated with a lower risk of testing positive for COVID-19 and being hospitalized due to COVID-19. The study analyzed data from over 110,000 individuals with baseline n-3 FA levels measured and followed for over 10 years. 

Another study published in the journal "Prostaglandins, Leukotrienes and Essential Fatty Acids" analyzed data from a UK biobank of 440,000 participants and found a strong, inverse, and dose-related relationship between plasma DHA% and the risk of having a positive SARS-CoV-2 test result. The study also found that individuals with higher levels of omega-3 fatty acids were less likely to be hospitalized due to COVID-19. [2]

A study published in the American Journal of Clinical Nutrition has found that higher levels of omega-3 fatty acids, specifically DHA, may reduce the risk of hospitalization due to COVID-19. The study analyzed blood samples from over 1000 participants in a large US health study, looking at the levels of omega-3 fatty acids in their blood and any subsequent COVID-19 diagnosis, hospitalization, or death. Participants with higher levels of DHA were found to have a 40% lower risk of COVID-19 hospitalization compared to those with lower levels. 

Omega-3 fatty acids, particularly DHA, have anti-inflammatory actions. They are the main precursors for inflammation-resolving mediators, including maresins, resolvins, and protectins. These mediators downregulate the production of cytokines, improve macrophage-mediated removal of inflammatory debris and microbes and promote apoptosis of neutrophils. Accordingly, higher levels of EPA and DHA in the tissues could reduce the severity of the inflammatory response to SARS-CoV-2 infection. Small-scale studies have reported that higher RBC levels of EPA + DHA (i.e., the Omega-3 Index [O3I]) at admission were associated with a lower risk of adverse COVID-19 outcomes. 

However, it is important to note that there may be limitations to these studies that may affect the generalizability of the findings. For example, some studies were conducted on a small scale (<100 patients) and may not represent the general population. Additionally, some studies did not control for other factors that may affect COVID-19 outcomes, such as age, sex, race, underlying health conditions, and socioeconomic status. Therefore, further research is needed to confirm these findings and determine the mechanisms by which omega-3 fatty acids may affect COVID-19 outcomes. 

[source: https://www.sciencedirect.com/science/article/pii/S0002916522105356?via%3Dihub#bib2]