SARS-CoV-2 RNA and antibodies in tear fluid

Area of Science:

• Ophthalmology
• Virology
• Immunology

Background:

• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly contagious.
• Extrapulmonary transmission routes, including the eyes, require further investigation.
• The local immune response in tears against SARS-CoV-2 has not been studied.

Purpose of the Study:

• To assess the prevalence of SARS-CoV-2 RNA in tear fluid.
• To evaluate the local humoral immune response (IgG and IgA) in tears.
• To determine if tears can serve as a non-invasive surrogate for serum immune monitoring.

Main Methods:

• Nasopharyngeal and tear sampling in 26 acutely ill COVID-19 patients to detect SARS-CoV-2 RNA via RT-PCR.
• Comparison of IgG and IgA responses to SARS-CoV-2 spike protein in serum and tears of convalescent individuals (n=22) versus controls (n=15) using ELISA.

Main Results:

• SARS-CoV-2 RNA was detected in 26.9% of COVID-19 patients' tears, irrespective of ocular symptoms.
• Convalescent individuals showed significantly higher IgG and IgA levels in tears compared to controls.
• Tear IgG demonstrated 77.3% sensitivity and 93.3% specificity; IgA showed 59.1% sensitivity and 100% specificity.

Conclusions:

• Tear fluid harbors SARS-CoV-2 RNA and mounts a local IgG and IgA immune response.
• These findings support the eye as a potential SARS-CoV-2 transmission route.
• Tears represent a promising non-invasive biomarker for monitoring host immune response to SARS-CoV-2.