RNA SARS-CoV-2 Persistence in the Lung of Severe COVID-19 Patients: A Case Series of Autopsies
A detailed study, published in Frontiers in Microbiology, investigated the persistence of SARS-CoV-2 RNA in patients who succumbed to severe COVID-19, focusing on those who experienced prolonged illness. The study presents an autopsy series of 27 patients, including 26 adults and one pediatric patient, with a median illness duration of 39 days (ranging from 9 to 108 days).
- Viral Persistence in Lung Tissue: The study found genomic RNA (gRNA) of SARS-CoV-2 in the lung tissue of almost all patients, including those with prolonged illness. Subgenomic RNA (sgRNA) was detected in 64.7% of patients with illness duration up to 6 weeks and in 33.3% of patients with illness duration over 6 weeks. Notably, viral protein, gRNA, and sgRNA were detected in a pediatric patient’s lung cells after 95 days of illness.
- Viral Load Dynamics: The investigation revealed that in cases with less than two weeks of illness, viral protein and mRNA were detectable using immunohistochemistry and in situ hybridization. However, these markers were not found in patients with illness durations exceeding two weeks, suggesting a decline in detectable viral replication over time.
- Role of Host Immunity and Co-infections: The study suggests that persistent viral shedding in the lungs may be linked to host immunity, especially in severe COVID-19 cases and immunocompromised individuals. Patients with critical illness and those under immunomodulatory therapy may have difficulty eliminating the virus, contributing to the persistence of chronic lung lesions. Additionally, 13 patients in the series had secondary pulmonary infections, highlighting the risk of co-infections in severely ill COVID-19 patients.
- Implications for Immunocompromised Populations: The findings indicate that immunocompromised individuals, including those with primary immunodeficiencies like the pediatric patient in the study, are more susceptible to prolonged viral infections. These patients may require special consideration for antiviral treatment.
In conclusion, the study provides critical insights into the persistence of SARS-CoV-2 in severe COVID-19 cases, emphasizing the role of host immunity and the impact of secondary infections. It underscores the complexity of managing severe COVID-19, particularly in immunocompromised individuals, and the need for ongoing research into effective treatment strategies.