As COVID-19 cases continue to periodically rise, some patients experience symptoms long after recovering from the acute infection, according to a Houston Methodist study recently published in Nature’s Scientific Reports. Lead author Sonia Villapol, PhD, an assistant professor of neurosurgery at Houston Methodist's Center for Neuroregeneration, and her collaborators detected more than 50 long-term effects of COVID-19 among the 47,910 patients included in the analysis. The most common of these lingering symptoms, which range from mild to debilitating and last weeks to months after initial recovery, are fatigue at 58% followed by headache (44%), attention disorder (27%), hair loss (25%), shortness of breath (24%), loss of taste (23%) and loss of smell (21%). Other symptoms were related to lung disease such as cough, chest discomfort, reduced pulmonary diffusing capacity, sleep apnea and pulmonary fibrosis; cardiovascular issues, such as arrhythmias and myocarditis; and unspecific problems, such as tinnitus and night sweats. The researchers were surprised to also find a prevalence of neurological symptoms such as dementia, depression, anxiety and obsessive-compulsive disorders.

The research team performed a systematic review and meta-analysis of these studies to estimate the prevalence of all the symptoms, signs or abnormal laboratory parameters extending beyond the acute phase of COVID-19. They measured several biomarkers, including abnormal chest x-ray or computed tomography scan, blood clot risk, presence of inflammation, anemia, and indicators of possible heart failure, bacterial infection and lung damage. They found that 80% of recovered adults had at least one long-term symptom lasting weeks to months after acute infection with mild, moderate or severe COVID-19. In total, the team identified 55 persistent symptoms, signs and abnormal laboratory results, with most of the lingering effects similar to the symptomatology developed during the acute phase of COVID-19. Identifying these same persistent effects across several countries, the researchers say their study confirms that the burden of long COVID is substantial, and they stress the urgency of recognizing these chronic complications, clearly communicating them to the community, and defining therapeutic strategies to avoid long-term consequences from COVID-19. The next phase of their research is focused on determining what makes some individuals more susceptible to long COVID.

Although COVID-19 is primarily a respiratory disease, during early stages of infection many patients experience gastrointestinal symptoms such as nausea, vomiting or diarrhea. Such gastrointestinal changes create an imbalance in gut microflora that can cause the release of proinflammatory cytokines. Villapol’s team will analyze the changes in gut microbiota in patients who tested positive for SARS-CoV-2. Saliva and stool samples will be collected when they test positive and after 2 weeks and 6 months. By providing a snapshot of how the gut microflora changes over time, this research could shed some light on possible associations between gut dysbiosis and long COVID. Once the gut microflora changes are characterized, therapeutic approaches with pre- or probiotics could be used to correct the microbiome imbalance and help mitigate the effects of long COVID.