Testing the Sensitivity of Conjunctival Swabs from Confirmed COVID-19 Patients

Abstract

Objective To investigate the incidence of COVID-19 viral RNA in the conjunctiva of patients priorly confirmed to have COVID-19, using a conjunctival swab and to determine swab sensitivity. Methods This cross-sectional study enrolled patients who tested positive for COVID-19 with PCR via nasopharyngeal swabs. Conjunctival swabs were collected for each patient and subjected to RT-PCR assay. Demographic data and clinical history of patients were investigated and analysed. Results In this study, 4.9% of the patients tested positive with conjunctival swabs for COVID-19; 29.9%, 28.7%, 20.1%, and 12.2% of the patients had fever, shortness of breath, cough, and red eye, respectively. Among all patients, 18.9% and 73.2% had a history of traveling and contact with positive COVID-19 cases, respectively. There were significant correlations between the conjunctival results and diabetes (P=0.049) and hypertension (P=0.002). Traveling was a risk factor for positive conjunctival swab testing (P=0.016). The sensitivity of the conjunctival swab was 4.8%. Conclusion Among all positive cases of COVID-19, a small percentage had positive results when tested using a conjunctival swab. Conjunctival swabs have very low sensitivity for the detection of COVID-19. However, tears could still be a mode of disease transmission, especially from patients to eye care specialists.

Incidence and clinical characteristic of ocular surface manifestation: an evaluation of conjunctival swab results in Corona Virus 2019 (COVID-19) patients in Jakarta, Indonesia

“…This was also supported by meta-analysis done by Aggarwal et al, which reported low positivity rate of only 3.5% in patients with or without ocular symptoms [31]. These studies along with our results suggested that the occurrence of conjunctivitis is a systemic response rather than local activity of the virus on the ocular surface [5,10,13].…”

“…Lastly, the low number of ACE-2 receptors to have been shown in conjunctival tissue (< 50% lower than other tissues), thus their ability to bind to the virus is very poor [25,26]. It is also possible that the viruses appear at specific period of time in the ocular surface, thus requiring price collection time in order to gain positive results [10,27]. Other studies have supported these findings, reporting the low rates of positive conjunctival swab results ranged from 0 to 15.6% [1,2,16,20,28,29].…”

“…Several studies have investigated the correlation between SARS-CoV-2 infection and its ocular manifestations, however many results remained controversial [1][2][3]. The ocular manifestations reported ranged from simple conjunctivitis with symptoms of red eyes, epiphora, conjunctival secretion, and chemosis to keratoconjunctivitis, posterior uveitis, retinitis, and optic neuritis, which affect visual acuity [4][5][6]10]. The prevalence of conjunctivitis in studies widely varied, ranging from 2 to 31% [7,11,12].…”