Study of Conjunctival Carriage of SARS-CoV2 using Serial Sampling: Risk factors and Protective factors

LIU, Shasha; YEUNG, Tiffany Lok Man; TSO, Eugene Yuk Keung; FUNG, Kitty Sau Chung; TANG, Emily Wai Ho; LI, Kenneth Kai Wang

OBJECTIVE: The conflicting results of conjunctival carriage of SARS-CoV2 in current literature may be due to variabilities in sampling technique and sampling time window. In this study, we set out to standardize the sampling times and sampling technique in order to minimize the risk of false negative results. DESIGN: A prospective observational study METHOD: Thirty-nine consecutive COVID19 patients admitted to a regional hospital in Hong Kong underwent 2 serial conjunctival swabs for RT-PCR analysis (one on admission and another prior to discharge). Using clear instructional video, standardized technique for conjunctival sampling was adopted,. Patient's medical history, ocular symptoms, nasopharyngeal SARS-CoV2 results and personal hygiene habits were prospectively collected and analyzed. RESULTS: The majority had mild to moderate COVID19 disease (89.74% of study subjects). 15.38% reported symptoms suggestive of ocular surface inflammation, including epiphora (10.25%), itchiness (7.69%) and foreign body sensation (5.13%). Only 1 (2.56%) case had bilateral overt conjunctivitis. There was no correlation between the COVID19 severity and ocular symptoms. Despite obtaining adequate samples, SARS-CoV2 was not detected in all 78 conjunctival samples. CONCLUSION: Even after adoption of standardized sampling technique, our study could not detect conjunctival carriage of SARS-CoV2 in mild to moderate COVID patients. However, our group of patients practiced good personal hygiene, with universal masking, frequent hand washing and mobile phone sanitation. Further studies to investigate the contribution of personal hygiene on conjunctiva transmission as well as self-inoculation is warranted.