Lasting Changes to Circulating Leukocytes in People with Mild SARS-CoV-2 Infections

Area of Science:

• Immunology
• Infectious Diseases
• Virology

Background:

• Severe SARS-CoV-2 infections are known to cause long-term health issues.
• The long-term health consequences for individuals with mild or asymptomatic SARS-CoV-2 infections remain largely unknown.

Purpose of the Study:

• To investigate lasting changes in immune phenotype and function after mild SARS-CoV-2 infections.
• To compare immune responses in mild SARS-CoV-2 survivors to those who recovered from other mild respiratory infections.

Main Methods:

• Assessed soluble inflammatory factors, including C-reactive protein.
• Analyzed the phenotype and function of circulating T-cells.
• Examined markers of monocyte activation and receptor expression related to cell migration.

Main Results:

• Individuals with mild SARS-CoV-2 showed elevated C-reactive protein and altered T-cell function 1-3 months post-infection.
• Monocyte activation markers were higher in mild SARS-CoV-2 survivors at 1-3 months but normalized by 6-9 months.
• T-cells from recent mild SARS-CoV-2 infections were more responsive to polyclonal stimulation compared to controls.

Conclusions:

• Mild SARS-CoV-2 infections can lead to prolonged immune activation and systemic inflammation persisting for at least three months.
• Specific immune changes, including T-cell alterations, are observed even after non-severe COVID-19.
• These findings highlight the potential for long-term immune sequelae following mild SARS-CoV-2 infections.