The long-term effects of COVID-19 on oxygen carrying capacity in adults at the University of Limpopo, South Africa.

Background: Long-COVID is a condition characterized by persistent symptoms that last past the acute phase of COVID-19. The symptoms manifest from COVID-19 infection, and include shortness of breath, fatigue, and headaches. These symptoms could be caused by hypoxia and hypoxemia which may result from low haematocrit and hemoglobin. The SARS-CoV-2 virus causes destruction to the heme group of hemoglobin leading to haemolysis, which may lead to disrupted oxygen-carrying capacity. Aim: The aim of the study was to investigate the long-term effects of COVID-19 on hemoglobin (Hb) and haematocrit (Hct) in adults. Methodology: This was a case-control cross-sectional study that included a COVID-19 non-naive group (n = 28) and a COVID-19 naïve group (n = 196). Questionnaires were administered to participants, and blood levels of Hb and Hct were measured. Furthermore, a food frequency questionnaire (FFQ) was administered to determine the daily intake of iron, folic acid, and vitamin B12 to observe if the diet might have had an influence on Hb and Hct. Results: The results show a trend for a low Hct is common in females who had a history of a positive COVID-19 test, and the trend for a normal Hb is prominent across the study population. Results also show a statistically significant (p = 0.001; 95% CI -1.064 to 9.295) intake of vitamin B12 in COVID-19 non-naive males, who also showed to have the highest levels of Hb and Hct (mean of 45.86 g/dl and 15.57% respectively) as compared to other groups. Conclusion: COVID-19 patients in this study experienced persistent symptoms, but most of the participants had no symptoms at the time the study was conducted. Diet might have had an impact on Hb and Hct in the COVID-19 non-naive male population, as it was observed that they had the highest nutrient consumption and the highest concentrations.